2.0 (98 Degrees album)
2.0 is the fifth studio album by American boy band 98 Degrees. The album was released on May 7, 2013 through eOne Music. It is their first studio album in thirteen years following Revelation (2000), The album was released by eOne Music, making it their first released through an independent record label rather than a major label like Motown or Universal Records. 2.0 debuted at number 65 on the Billboard 200, and number 12 on the Independent Album chart becoming the group's lowest-charting album since their 1997 debut album, 98 Degrees, which debuted at number 145.


2.0 (Big Data album)
2.0 is the debut studio album by electronic music band Big Data. It was released on March 20, 2015 under Warner Bros. Records. From the album, two singles have been released; titled "Dangerous" featuring indie rock band Joywave and "The Business of Emotion" featuring White Sea.


2.0 (Big Data album)
The album peaked at 75 on the Billboard 200 chart.


2.0 (Big Data album)
This song "Clean" featuring Jamie Lidell featured in Konami video game, Pro Evolution Soccer 2017; "The Business of Emotion" was re-recorded in Simlish for the video game The Sims 4.


2.0 (Citizen Way album)
2.0 is the second major label studio album by Citizen Way. Fair Trade Services released the album on March 11, 2016.


2.0 (Citizen Way album), Critical reception
Andy Argyrakis, indicating in a four star review at CCM Magazine, writes, "Get ready for an onslaught of anthems as Citizen Way turns in its second long player, which finds the guys even more seasoned than the first time around following three years of tireless touring." Awarding the album four stars from New Release Today, Amanda Brogan-DeWilde states, "Citizen Way takes that journey with you, and entertains you with some catchy tunes on the way."


2.0 (Citizen Way album), Critical reception
Jonathan Andre, giving the album four stars at 365 Days of Inspiring Media, writes, "Ben and the rest of the band for creating 11 moments of inspiration, encouragement and heartfelt moments of poignancy!" Reviewing the album for Today's Christian Entertainment, Kelly Meade describes, "With their positive, upbeat approach to contemporary Christian music, Citizen Way brings a collection of encouraging anthems while keeping the message of God's love [and] faithfulness center stage."


2.0 (Citizen Way album), Critical reception
Chris Major, rating the album a 4.7 by The Christian Beat, says, "Undeniably adventurous and energetic, 2.0 takes the originally high bar set by Citizen Way and raises it even further... The verdict is in - Citizen Way 2.0 is an absolute must listen for fans of any genre of Christian music... Most certainly, 2.0 marks a new era for Citizen Way filled with new sounds, impactful lyrics, and exciting possibilities." Signaling in a two and a half star review from Jesus Freak Hideout, Mark Rice says, "Citizen Way has totally lost their identity on 2.0. While moments of clever songwriting and an energetic opening track elevate the album above a total pass, it is hard to understand the band's decision here to abandon an approach that they could have pursued and perfected just to leap into mediocrity by starting all over from scratch."


2.0 (film)
2.0 is a 2018 Indian Tamil-language science fiction action film written and directed by S. Shankar, and co-written by B. Jeyamohan. Produced by Subaskaran under the banner of Lyca Productions. As the second instalment in the Enthiran franchise, 2.0 is a standalone sequel to Enthiran (2010), featuring Rajinikanth reprising the roles of Vaseegaran and Chitti as the Robot, alongside Akshay Kumar as Pakshi Rajan and Amy Jackson as Nila and also Sudhanshu Pandey, Adil Hussain, Kalabhavan Shajohn, and K. Ganesh appear in supporting roles. The film follows the conflict between Chitti, the once dismantled humanoid robot, and Pakshi Rajan, a former ornithologist who seeks vengeance upon cell phone users to prevent avian population decline. The soundtrack is composed by A. R. Rahman, with lyrics written by Madhan Karky and Na. Muthukumar.


2.0 (film)
Produced on an estimated budget of ₹575 crore (US$81 million), 2.0 is the most expensive Indian film to date. Production began in 2015, with principal photography conducted at AVM Studios later that year. The first schedule was filmed at EVP World. Scenes were primarily shot in India, particularly in Chennai's Madras Boat Club and Delhi's Jawaharlal Nehru Stadium. Filming was completed by August 2017. The film is the first in Indian cinema to be natively shot in 3D, which was done by cinematographer Nirav Shah. The film was primarily shot in Tamil while Akshay Kumar's dialogues were shot in Hindi. Legacy Effects made their return to construct prosthetic makeup and animatronics, with visual effects supervised by V. Srinivas Mohan. Editing was handled by Anthony and production design was conducted by T. Muthuraj.


2.0 (film)
2.0 was released worldwide in both 3D and conventional format on 29 November 2018, along with its dubbed versions in Hindi and Telugu. It received mostly positive reviews upon release. Critics particularly praised the film's visual effects, performances of Rajinikanth and Kumar, and social message; the pace and screenplay received criticism. It earned ₹117.34 crore (US$16 million) worldwide on its first day, which was the second-highest ever for an Indian film. The film crossed ₹520 crore (equivalent to ₹560 crore or US$78 million in 2019) in its opening weekend to be the highest-grossing film worldwide for that week. 2.0 is the second highest-grossing film in India and is the fifth highest-grossing Indian film worldwide.


2.0 (film), Plot
Dr. Vaseegaran has recently built a new android humanoid assistant named Nila, whom he introduces to a group of college students. Shortly after, all the mobile phones in the city begin to fly into the sky, throwing the public into a panic. A scientific council assembles to discuss the phenomenon, in which Vaseegaran suggests reactivating the robot Chitti. But the plan is opposed by a member of the council, Dhinendra Bohra, whose father was killed by Chitti a few years back.


2.0 (film), Plot
The cell phones gather into a swarm and kill phone retail store owner Jayanth Kumar, telecom company owner Manoj Lula, and Telecom Minister Vaira Moorthy. The Home Minister S. Vijay Kumar gives permission for Vaseegaran to reactivate Chitti, whom he has already started working on. The cell phone swarm destroys phone towers around the city and wreaks havoc on the public, manifesting as a giant bird. A newly activated and upgraded Chitti battles the bird in the city and destroys it with an explosion. The remaining phones retreat and reform. Chitti, who runs out of battery takes refuge in three antennas at a space station. The bird tries to follow but is repelled by the antennas.


2.0 (film), Plot
Chitti informs Vaseegaran about this incident and confirms that the phones are powered by an aura, specifically a concentrated mass of negative charge with electromagnetic properties. Since the space station was streaming positive charged ions into space, the bird was repelled. Vaseegaran builds a photon synthesizer that projects positive charge, intending to neutralise the charge of the bird. The group confronts the bird and drains it of power. The phones take up a humanoid form, as the deceased ornithologist Pakshi Rajan.


2.0 (film), Plot
Chitti converses with Pakshi as he attempts to destroy the synthesizer, in which a flashback reveals that Pakshi protested against the usage of modern mobile phones, from which the radiation affected the brains of birds and caused mass deaths, especially near his bird sanctuary and home in Thirukazhukundram. Pakshi makes conferences and protests to address this, but the public dismisses and mocks him. Lula and Moorthy also reject his morals for their business and Jayanth Kumar shuns him from his shop as he tries to protest. Birds all over the city including Pakshi's sanctuary die out, including newborn chicks.


2.0 (film), Plot
A distraught and angered Pakshi, after even a court investigation found no violations (because telecom companies reduced signal levels to conceal wrongdoing), hangs himself at a cell tower. Pakshi's negatively charged spirit reawakens by the radiation emitting from the tower. By absorbing the souls of all the deceased birds in the city, he becomes a vengeful entity.


2.0 (film), Plot
Chitti tries to convince Pakshi not to hurt the public but Pakshi wishes to punish their ignorance. Chitti has Pakshi captured and contained. The news spreads to the council which decides to build an army of such robots for the military. Dhinendra, who becomes angered by Chitti's victory, releases Pakshi's spirit from the synthesizer. Pakshi possesses Vaseegaran and attacks the public again, but Chitti refuses to attack his creator. Nila gets the red chip and reprograms Chitti to his evil 2.0 alter ego, after altering it to not harm the innocent and commanding him only to fight Pakshi.


2.0 (film), Plot
Pakshi traps 80,000 people in a football stadium and kills Dhinendra, who was present, by focusing radiation from multiple cell towers. Chitti interferes and fights Pakshi's bird form with his army. As Chitti runs out of charge, Pakshi turns into his winged form and creates several bird drones. The drones tear the robots into pieces, but before Pakshi can summon radiation he's interrupted by one of Chitti's creations: the action figure bot Kutti 3.0. Released into the stadium by Nila, the Kutti bots mount themselves on doves, forcing Pakshi to stand down. The Kuttis self-destruct and destroy Pakshi's drones. After Vaseegaran is released from possession, Pakshi is led to the space station where he is destroyed.


2.0 (film), Plot
Vaseegaran recovers in the hospital and tells Vijay Kumar, who comes to see him, that he feels Pakshi Rajan was a virtuous person who became a victim of the corrupt society. He also suggests we reduce and control cell phone radiation and ensure that technology do not threaten the lives of all the living creatures in the world. Chitti, now restored to its original version, begins a relationship with Nila.


2.0 (film), Plot
In a post-credits scene, Sana asks Vaseegaran over the phone about the probability of mobile phones flying again. Immediately, Vaseegaran's mobile flies out of his hand and morphs into Kutti 3.0, saying, "I am your grandson".


2.0 (film), Production, Development
The commercial success of Enthiran (2010) prompted the makers of the film to immediately consider making a sequel. By March 2011, the original film's cinematographer, Rathnavelu, revealed that initial pre-production work on a sequel had begun with the same technical team. S. Shankar, the director of Enthiran, moved on to work on Nanban (2012) and I (2015) and planned to reunite with the same producers as the original was released, with Shankar revealing that he was unsure if the film "will happen at all" during an interview in 2014. While finishing the production of I, Shankar drafted the scripts of three more feature films, including a sequel to Enthiran.


2.0 (film), Production, Development
Pre -production work for the film had reportedly started in June 2015 with Lyca Productions deciding to finance the project. Along with Shankar and Rajinikanth, composer A. R. Rahman and editor Anthony remained on the development team for the sequel, while Jeyamohan was added to write the screenplay. Shankar also began briefing the film's art director T. Muthuraj and visual effects supervisor V. Srinivas Mohan about their involvement in the film. Shankar had initially inquired about K. V. Anand's availability. This was before Nirav Shah joined the technical team as a cinematographer in mid-2015 and visited specialist studios in the United States to research filming methods for 3D shoots.


2.0 (film), Production, Development
Jeyamohan finished work on the script of the film in September 2015 and revealed that the story would be a direct continuation of the 2010 film, with filming only set to start following the completion of Rajinikanth's commitments in Kabali (2016). The original film's screenplay writer, Madhan Karky, helped Jeyamohan on some of the more technical dialogue in the script. While the film does include characters and references to events from its predecessor, it is primarily a standalone sequel.


2.0 (film), Production, Development
A press release coinciding with the start of the film's shoot also revealed that Resul Pookutty would handle sound designing, Legacy Effects would take care of animatronics work and Mary E. Vogt would design special costumes. Stunt choreographer Kenny Bates and visual effects specialists John Hughes and Walt Jones of Tau Films were also signed to work on the film. Unadjusted for inflation, 2.0 is so far the most expensive Indian film.


2.0 (film), Production, Casting
Shankar held initial discussions with Kamal Haasan, Aamir Khan, and then Vikram about portraying a further role, though none of the three actors signed on to appear in the film. Subsequently, the team held talks with Hollywood actor Arnold Schwarzenegger for the role, who agreed to work on the film for a record remuneration. The makers then opted against signing Schwarzenegger, though there have been conflicting reasons regarding this decision. British actress Amy Jackson signed on to work on the film in October 2015 and visited Los Angeles as a part of the team's pre-production work.


2.0 (film), Production, Casting
In late November 2015, Rajinikanth also travelled to Los Angeles to meet the film's producers and complete costume trials and initial motion capture effects work for the film. After further negotiations with actors including Hrithik Roshan and Neil Nitin Mukesh, the makers signed on Akshay Kumar to portray the role for which Schwarzenegger was initially considered.


2.0 (film), Production, Casting
Sudhanshu Pandey joined the cast of the film in March 2016 and revealed that he would portray a scientist who is the son of Professor Bohra from the original film. Adil Hussain began working on the film in July 2016, and, as a part of his role, undertook extensive research into the life of news reporters. In September 2016, Malayalam actor Kalabhavan Shajohn confirmed that he had tried out for a role in the film after Shankar was impressed with his performance in Drishyam and had signed him on.


2.0 (film), Production, Filming
An official launch event was to be held on 12 December 2015, coinciding with Rajinikanth's birthday. However, the team chose to avoid publicity as a result of the 2015 South Indian floods. Instead, the team held a low key launch event at the AVM Studios on 7 December, with the director and the producers in attendance. Titled 2.0, the film then began its first scheduled shooting on 16 December 2015 at a set erected in the outskirts of Chennai at EVP World.


2.0 (film), Production, Filming
On the first day of the shoot, a scene featuring Rajinikanth and several dwarf actors was shot at the erected set, while the team's principal cast and crew also assembled for a photoshoot. The first schedule of the film, consisting of Rajinikanth and Amy Jackson, continued in Chennai until 30 December 2015. The team then worked on a second schedule throughout the middle of January 2016 in Chennai and shot scenes featuring Rajinikanth at Mohan Studios and by Madras Boat Club.


2.0 (film), Production, Filming
Shankar continued filming portions not involving the lead actors throughout February 2016 in Chennai, with a car chase sequence shot in Royapettah. Another schedule to shoot a song was initially set to be held at Salar de Uyuni in Bolivia but was cancelled due to bad weather, and the team opted not to travel to the country.


2.0 (film), Production, Filming
Akshay began shooting for the film in Chennai at the beginning of March 2016 and took part in a schedule held at the EVP Film City studio in Chennai. A set of a mobile phone store was built on-site, while night scenes involving robotic equipment and military tanks were also canned. The team subsequently moved to Delhi in order to hold a forty-five-day schedule, continuing on from the same scenes with military tanks that were shot in Chennai.


2.0 (film), Production, Filming
Subsequently, the team filmed sequences at Jawaharlal Nehru Stadium depicting an Indian Super League match between Chennaiyin FC and Mumbai City FC, with hundreds of junior artists recruited to act as supporters. Actors Amitabh Bachchan and Abhishek Bachchan visited the film's set at the stadium with the media reporting that the pair were set to make cameo appearances, though the claim was later denied by the team. Rajinikanth then joined the team in Delhi at the end of March to continue shooting for the project, with the climax sequences being filmed. Action scenes incorporating robotic equipment were filmed throughout early April in Delhi, with cinematographer Nirav Shah using helicams to capture sequences involving the three lead actors.


2.0 (film), Production, Filming
Another ten-day schedule took place in May 2016 in Chennai, with scenes being shot at the EVP Film City studios as well as at The Forum Vijaya shopping mall. During the shoot at the studios, the visual effects designer Srinivas Mohan digitally converted a green screen sequence into locations including the Red Fort and the Parliament from Delhi after the team were unable to secure shooting permission there. By June 2016, Shankar revealed that after one hundred days of shooting, scenes including the climax and two major action sequences had been completed and that the film was fifty percent complete.


2.0 (film), Production, Filming
Adil Hussain and Kalabhavan Shajohn began their work in the film during July 2016 in Chennai, while the rest of the cast were given an extended break after Rajinikanth fell ill. Production continued throughout August and early September 2016 without the lead actors in Saligramam in Chennai, where the team shot action sequences of luxury cars being blown up. Following his illness and subsequent recovery, Rajinikanth returned to the sets of the film in early October after a break of close to four months.


2.0 (film), Production, Filming
He shot for scenes alongside Amy Jackson in Chennai, where he was featured fighting huge birds created using animatronic technology with actor Riyaz Khan also joining the cast. Soon after the schedule finished in early October, Shankar revealed that the film was two-thirds complete, following one hundred and fifty days of shooting.


2.0 (film), Production, Filming
Another schedule began in early November at EVP Film City in Chennai with all of the lead cast and continued throughout the month. All filming was completed except for one song that featured a set erected in Chennai. Jackson was given ten days of practice by choreographer Bosco. Filming was completed in August 2017. Principal photography was concluded on 22 October 2017.


2.0 (film), Music
A. R. Rahman composed the film's soundtrack and score, during the pre-production works of the film, in December 2015. Recording of the songs took place for nearly four years. In an interview with Archana Chandhok on Zee Tamil, Rajinikanth revealed that director Shankar wanted to make 2.0 without any songs. However, Rahman was still not convinced and felt that an album should have a minimum of four songs to provide listeners with a wholesome experience.


2.0 (film), Music
A promotional music event for the film was held at Burj Al Arab, Dubai on 27 October 2017, in a grand manner. And on the same day, two tracks from the film, "Endhira Logathu Sundhariye" and "Rajaali" were released, in Tamil and dubbed versions in Telugu and Hindi Madhan Karky and Na. Muthukumar provided the lyrics for the songs in Tamil . The third track, "Pullinangal" was included in the part of the soundtrack album on 6 November 2018.


2.0 (film), Music
The film score was released on 29 June 2019. Recording of the original score began in London and Rahman's Los Angeles studios in 2016. Unlike previous projects, Rahman began finalising the original background score six months back prior to release because he felt that the scenes were very heavy and it needed a lot of work.


2.0 (film), Marketing and release
In November 2016, it was revealed that 2.0 was scheduled for release during Diwali on 18 October 2017. In April 2017, Raju Mahalingam, the film's former producer, announced that the film's release had been postponed to 25 January 2018 citing better incorporation of visual effects. The release date was later moved to 14 April 2018. The release date was once again moved to 27 April 2018 but instead Kaala took that spot resulting in another delay of the film. The making video of the film was revealed on 25 August 2017. The film, which contains approximately 1,000 visual effects shots according to producers, was delayed numerous times while the computer-generated imagery (CGI) work was being completed by numerous effects studios. The film was finally slated to be released in cinemas on 29 November 2018.


2.0 (film), Marketing and release
The teaser of 2.0 was released on Ganesh Chaturti, 13 September 2018, in both 3D and 2D. The 3D version was positively received, while some expressed disappointment with the 2D. Its 2D teaser video has been viewed over 32 million times in 24 hours. The film topic was trended and top searched queries on Google Trends for a week. But the teaser did not mention the release date. According to the source, "There may be a lot of VFX work left in the film and they do not want to delay things too much.


2.0 (film), Marketing and release
This is why, the makers Lyca Productions seem to have put out the teaser so that they can keep the audiences busy." In addition to its original language, the film will be released in 14 other languages with dubbed versions. The film has recovered approximately ₹370 crore (equivalent to ₹398 crore or US$56 million in 2019) from satellite, digital and music rights. This includes, but is not limited to, about ₹110 crore (equivalent to ₹118 crore or US$17 million in 2019) for satellite and digital rights and ₹50 crore (equivalent to ₹54 crore or US$7.5 million in 2019) for digital rights, the latter sold to Amazon Prime Video.


2.0 (film), Marketing and release
Ahead of the film's release, the Cellular Operators Association of India (COAI) lodged a complaint, demanding that the Central Board of Film Certification (CBFC) certificate of the film be revoked for "promoting anti-scientific attitudes towards mobile phones and cellular networks". The organisation alleged the producers "falsely depicting mobile phones and mobile towers as harmful to living creatures and the environment including birds and human beings". Meanwhile, a Lyca Productions spokesperson said, "We are under no obligation to toe the line and the film does not hunt or defames [sic] anyone." Various studies in India have proven that electromagnetic radiation from cell sites has a detrimental effect on bird health.


2.0 (film), Marketing and release
In China, the film released on 6 September 2019. It was said to be released by HY Media in 10,000 theatres with 56,000 screenings, which includes 47,000 3D screenings, which is the largest release ever for an Indian film in the country in May 2019, with a Mandarin dub and subtitles, but the release was delayed to 6 September 2019 and released in about 48,000 screens. A dubbed Russian-language version of the film will also release in Russia on 25 July 2019.


2.0 (film), Reception, Box office
2.0 was released in about 6900 screens in India and over 2000 screens overseas. On its opening day, 2.0 earned about ₹80 crore (equivalent to ₹86 crore or US$12 million in 2019) gross collection in India (all versions), which was the second highest ever for an Indian film after Baahubali 2: The Conclusion (2017)'s ₹154 crore (equivalent to ₹174 crore or US$24 million in 2019). This was around ₹ 64 crore nett.


2.0 (film), Reception, Box office
Its worldwide gross was over ₹117.34 crore (equivalent to ₹126 crore or US$18 million in 2019), which was also the second highest worldwide collection for an Indian film on its first day after Baahubali 2. On its second day, the film went on to be number one at the Australian box office. In Malaysia, the film had an all-time highest opening for any Tamil film. On its second day, the film earned around ₹ 45 crore nett in India.


2.0 (film), Reception, Box office
The all-India business of 2.0 increased to ₹ 56–57 crore nett on Saturday (the third day) owing to positive word-of-mouth in North India, while the collections in South India saw a minor drop. Its all-India total increased to ₹ 165.5 crore nett. On its third day, the film earned around ₹290 crore (equivalent to ₹312 crore or US$44 million in 2019) worldwide in all languages, including ₹85 crore (equivalent to ₹92 crore or US$13 million in 2019) from overseas markets.


2.0 (film), Reception, Box office
At the American box office, the film surpassed the lifetime business of Rajinikanth's previous film Lingaa (2014) in just two days. The film debuted at number 11 at the American box office, earning $4.09 million. The screen count was increased from 20 to 75 in Pakistan on its second day to meet the demand. 2.0 grossed US$14.75 million (₹ 1.03 billion) in first five days in overseas markets.


2.0 (film), Reception, Box office
On its fourth day, a Sunday, business picked up over India, which led the film to accumulate an opening weekend collection of around ₹400 crore (US$56 million), the highest amount earned by any film in the week of 29 November to 2 December, ahead of Fantastic Beasts: The Crimes of Grindelwald (2018). Collections in India, discounting overseas, were ₹291 crore (equivalent to ₹328 crore or US$46 million in 2019) gross (₹ 229 crore nett) in all languages.


2.0 (film), Reception, Box office
This pushed it ahead of Enthiran, which was the previous highest-grossing film from Tamil cinema with an earning of ₹ 205 crore nett in India. In its four-day opening weekend, the film opened at number one at the United Arab Emirates box office, earning $2.5 million, ahead of Creed II (2018).


2.0 (film), Reception, Box office
On its fifth day, the film earned around ₹451 crore (US$56 million) worldwide in all languages, including ₹114 crore (US$16 million) from international markets. In North India, its Hindi version earned around ₹111 crore (US$16 million). Along with the sixth day business of ₹ 24 crore nett, the film earned ₹ 282.31 crore nett in India. It did record business in the southern Indian states of Tamil Nadu and Kerala. By the end of seven days, the film earned ₹480 crore (US$67 million) worldwide, which included ₹362 crore (US$51 million) in India and US$15 million (₹ 1.18 billion) in overseas markets. The extended first week worldwide collection was ₹520 crore (US$73 million).


2.0 (film), Reception, Critical response
On the review aggregation website Rotten Tomatoes, 2.0 has a 59% approval rating based on 17 reviews and an average rating of 5.39/10.


2.0 (film), Reception, Critical response, India
2.0 received generally positive reviews from critics in India. Shankar's direction, visual effects, performances of Rajinikanth and Kumar, suspense, and social message received praise, while the introduction, script, and dialogues drew criticism. Taran Adarsh gave the film five stars out of five and applauded Shankar as "a visionary... He hits the ball out of the park this time. Akshay Kumar is fantastic, while Rajinikanth is the boss".


2.0 (film), Reception, Critical response, India
A critic for Bollywood Hungama gave it four and a half stars out of five and similarly commended Shankar, "[His] direction is highly effective and he proves once again why he's one of our best filmmakers. He doesn't get overwhelmed by the technology available and makes correct use of it". S Subhakeerthana of The Indian Express gave it four stars out of five: "Shankar has raised the bar in filmmaking in terms of visualisation, grandeur, and every frame of his fascinates you as a viewer". Business Today's Ramesh Bala gave it four stars out of five, and found Kumar to be the film's spotlight: "He has rocked both as Birdman and as a normal man in an emotional flashback".


2.0 (film), Reception, Critical response, India
Writing for Hindustan Times, Raja Sen rated 2.0 three and a half stars out of five, terming Rajinikanth as "smarter than a smartphone" and counted him and Kumar among the film's strengths. A critic for the Indo-Asian News Service also gave three and a half stars out of five and wrote, "Unlike most science-fiction films, 2.0 takes the commercial route to entertain, thus does come across as illogical at places, but that's what makes it insanely fun". Devesh Sharma of Filmfare also gave three and a half stars out of five.


2.0 (film), Reception, Critical response, India
M. Suganth of The Times of India gave it three stars out of five; he stated that there is a sense of "just going through the motions in the first half," but found that the action sequences and chemistry between the leads helped keep the film enjoyable for most of its run-time. Writing for Film Companion, Anupama Chopra also gave the film three stars out of five: "2.0 is visually overpowering – the VFX are mostly first-rate – but the screenplay doesn't offer the seamless mix of romance, drama and comedy [as the predecessor]".


2.0 (film), Reception, Critical response, India
Janani K, film critic for India Today, gave 2.0 three stars out of five and appreciated the film's theme, but felt it could be better presented, writing, "Though it is a much-need [sic] message, it could have been explained in an intriguing manner rather than the pedantic treatment it gets". Rajeev Masand also gave it three stars out of five.


2.0 (film), Reception, Critical response, India
Shubhra Gupta of The Indian Express gave the film two stars out of five, describing it as "dull as ditchwater in the first half, perking up a little in the second, with a half-way watchable Akshay Kumar, and a Rajinikanth coming into his own right towards the end, for a bit". Pragati Saxena of National Herald concurred with Gupta and criticised the pace and dullness of the film. Writing for CNN-News18, Rohit Vats also rated two stars out of five and criticised the writing, opining, "[Shankar's] characters haven't evolved the way the world around them has". Saibal Chatterjee of NDTV also gave two stars out of five and said, "Bunkum is bunkum no matter how big the bucks behind it are".


2.0 (film), Reception, Critical response, Overseas
Simon Abrahams of RogerEbert.com gave the film three and a half stars out of four and stated, "Against all reason–against all common sense–2.0 works, and in a big, big way". Shilpa Jamkhandikar of Reuters wrote, "This film certainly has the look and feel of a big-ticket Hollywood production, and that alone is worth the price of the ticket". Kumar Shyam of The National gave it three and a half stars out of five and wrote, "2.0 is a very clever spectacle not to be missed for its sheer audacity and scale". Rafael Motamayor of Polygon wrote, "2.0's biggest draw is its impressive use of visual effects, and the film doesn't waste a moment to showcase its budget". He felt "[t]he effects [were] detailed enough to stand against a $200 million-dollar American blockbuster".


2.0 (soundtrack)
2.0 is the soundtrack album and score for the 2018 Indian Tamil science fiction action film of the same name. A. R. Rahman composed the feature film soundtrack and background score. The lyrics for the songs has been penned by Madhan Karky, Na. Muthukumar in Tamil.


2.0 (soundtrack)
Rahman was chosen to compose the songs, during the post-production works of the film in December 2015. The recording process for the songs and original score, took place for nearly four years. The soundtrack album was launched at a promotional event held on 27 October 2017, at Burj Al Arab, Dubai, where the film's cast and crew and other celebrities attended the event.


2.0 (soundtrack)
Two songs from the movie was released in Tamil, and also the dubbed versions in Telugu and Hindi, on the same day and A bonus track was released on 6 November 2018, in Tamil as well as the dubbed versions in Telugu and Hindi. The album received generally positive reviews from critics.


2.0 (soundtrack), Development
In 2015, during pre-production phase of the film, it was announced that A. R. Rahman would be composing the soundtrack and original score of 2.0.


2.0 (soundtrack), Development
In an interview with Archana Chandhok on Zee Tamil, Rajinikanth revealed that director Shankar wanted to make 2.0 without any songs. Plans for recording a title track and a background song failed. The track "Enthira Logathu Sundariye" made its way after taking into account that the screenplay of the film was entirely subject-oriented and moves at a frenetic pace. Keeping audiences in consideration, a "breather" form of a song was recorded. However, Rahman was still not convinced and felt that an album should have a minimum of four songs to provide listeners with a wholesome experience.


2.0 (soundtrack), Development
In an interview with Press Trust of India, Rahman stated that 2.0 was a tough film to score. Recording of "Endhira Logathu Sundariye" was completed by early August 2017. The song, reported as a romantic number with dance included, was shot indoors in a 12-day schedule in August 2017. Recording of the Hindi version ("Mechanical Sundariye") of the track was completed on 29 October 2017. The Hindi version of "Pullinangal" titled "Nanhi Si Jaan" was recorded in June 2018. About this, Rahman stated that he initially wanted to release more background themes rather than songs.


2.0 (soundtrack), Overview
Madhan Karky's lyrics in the duet Endhira Logathu Sundariye speak of a romance between a male and a female robot. "En uyire uyire batteriye, enai nee piriyaadhae" (My life, my life battery, do not leave me) or "Hey minsara samsarame" (My electronic wife) are in line with 2.0's storyline. Armaan Malik and Shashaa Tirupati have sung the Hindi version, while Sid Sriram and the latter have sung the Tamil and Telugu versions. The composition is not forgettable, but the trap music arrangement and the techno bleeps and bloops do come in way of the melody.


2.0 (soundtrack), Overview
There are subtle differences, lyrically, between the Tamil and the Hindi versions, that reveal how the makers perceive audiences in the South and the Hindi belt. If Endhira Logathu Sundariye has Sriram singing "Un bus-in conductor naan" (I am your bus conductor), in Mechanical Sundariye, written by Abbas Tyrewala, Malik sings "Hoon super conductor main" (I am a super conductor) – the idea being that Tamil audiences will appreciate the reference to Rajinikanth's early days.


2.0 (soundtrack), Overview
Raajali is an anthem-like number that celebrates the triumph of good over evil, a typical sentiment in Rajinikanth movies. The song begins with a reference to science fiction author Issac Asimov ("Isaac Asimov peran daa" – grandson of Issac Asimov) but it is merely casual name dropping, nothing clever.


2.0 (soundtrack), Overview
The best composition is Pullinangal, a sweet and sublime song that is an ode to birds. It is a theme song for the bird-loving villain, with the sweetness of the tune designed to draw him sympathy. Free from the mandate of having to be a theatre-shattering Rajinikanth song, the melodious Pullinangal's arrangement and mixing is low-key with strings, a simple synthetic beat, some piano and recordings of bird sounds. Na Muthukumar penned beautiful lyrics, in his very own trademark style.


2.0 (soundtrack), Overview
Though it is a love song that is ultimately not for a person, the singers (AR Ameen and Suzanne D’Mello sing all three versions, accompanied by Bamba Bakya in Tamil, Kailash Kher in Hindi, and fellow composer MM Keeravani in Telugu) sing their heart out, bringing an emotional weight missing from the other two tracks.


2.0 (soundtrack), Release
A promotional music event for the film was held at Burj Al Arab, Dubai on 27 October 2017, with Rajinikanth, Akshay Kumar, Amy Jackson, composer A. R. Rahman, director Shankar, producer Subaskaran and the film's entire technical crew, along with Dhanush, Aishwarya R. Dhanush, Kamal Hassan and other celebrities attended the event. The event was hosted together by RJ Balaji, Rana Daggubati and Karan Johar. The album features two songs "Endhira Logathu Sundhariye" and "Rajaali". Both these tracks were released on digital music platforms the same day.


2.0 (soundtrack), Release
A. R. Rahman and his music team performed these two songs and an additional track "Pullinangal" at the event. A symphony of an estimated 125 musicians was present to perform live. The audio launch event was telecasted on 19 November 2017 on Zee Tamil, and also telecasted once again on 2 December 2017 on News18 Tamil Nadu. The track "Pullinangal" was released as a part of the soundtrack album on 6 November 2018.


2.0 (soundtrack), Reception
Behindwoods has gave 3.25/5 rating to the album & wrote A.R.Rahman churns out yet another powerful album that seems to be binding with the story whilst adding to its 2.0's grandeur.


2.0 (soundtrack), Reception
Srinivasa Ramanujam, from The Hindu, reviewed the soundtrack album, stating that "The focus of Rahman's work in these two released songs for the Shankar-Rajinikanth film clearly seems to be on providing a futuristic soundscape rather than concentrating on tune – perhaps aligning with the sci-fi elements in the script."


2.0 (soundtrack), Reception
M Suganth, from The Times of India, reviewed the album, summarising it "As with Endhiran, Rahman has come up with songs that are global in sounding, but still distinctly local with 2.0."


2.0 (soundtrack), Reception
A reviewer from Firstpost reviewed the song "Endhira Logathu Sundhariye", stating that "Shashaa Tirupati kickstarts the song on a mysterious note and in trademark Robot style. Then, we are transported into lots of techno, groovy beats and some subtle melody as well. And suddenly, it strikes you. What stands out in the midst of this typical AR Rahman-Rajini track is Sid Sriram's vocals. The singer is a breath of fresh air in this album which otherwise has nothing we have not already heard of, and also reviewing "Raajali" as "the track that uplifts the soul of the movie.


2.0 (soundtrack), Reception
It is evident, through the pace of the track, that it is tailor-made for Rajini's role. One can typically imagine the superstar in a larger than life setup with this one. We must say, Rajali' might just be the 'Irumbile Oru Idhaiyam' (Enthiran) of 2.0. Sid Sriram, who is the new Arijit Singh of the South industry, is definitely the highlight of this album yet again.


2.0 (soundtrack), Reception
The singer who otherwise was known for his addictive melodies like "Yennai Matrum Kadhale" and the latest hit "Maruvaarthai" has proved that he can be the voice behind such peppy and high techno songs too". Finally the reviewer gave a verdict, stating that "The 2.0 songs released so far are a feast for Rajini's audience. The tracks are tailor-made for a plot like 2.0's. But we sure have heard better from Rahman. And yet, the "Neruppu Da" feels from Rajini's last outing Kabali, is yet to be witnessed in this jukebox".


2.0 (soundtrack), Background score
Recording of the original score began in London and Rahman's Los Angeles studios in 2016. Unlike previous projects, Rahman began finalising the original background score six months back prior to release because he felt that the scenes were very heavy and it needed a lot of work. The official film score consists of fifteen tracks with nearly a duration of nearly forty minutes. The film score was marketed and released on 29 June 2019.


2.0 (soundtrack), Album credits, Performer(s)
A. R. Rahman, Sid Sriram, Shashaa Tirupati, Blaaze, Arjun Chandy, Bamba Bakya, A. R. Ameen, Suzanne D'Mello, Nivas, M. M. Keeravani, Armaan Malik, Kailash Kher


2.0 (soundtrack), Album credits, Backing vocals
Deepthi Suresh, Veena Murali, Sowmya, Deepak Blue, Aravind Srinivas, Maalavika Sundar, Santhosh Hariharan, Niranjana Ramanan, Narayanan, Srinivas, Suryansh, Lavita Lobo, Aishwarya Kumar, Nakul Abhyankar, Shravan Sridhar, Srinivasan


2.0 (soundtrack), Album credits, Additional vocals
Arjun Chandy, Shenbagaraj, Nivas, Soundarya, Narayanan, Deepak Blue, Akshara, Madhura Dhara Talluri, Nakul Abhayankar, Shashwat Singh


2.0 (soundtrack), Album credits, Personnel
TR Krishna Chetan, Kumaran Sivamani, Ishaan Chhabra, Santosh Dhayanidhi, Pawan CH, Hari Dafusia, AH Kaashif, Jerry Vincent, Jim Sathya


2.01 (Buran-class spacecraft)
2.01 (GRAU index serial number 11F35 3K) is the designation of the third Buran-class orbiter to be produced as part of the Soviet/Russian Buran programme. Its construction was not complete when the Buran programme was cancelled (30–50 percent done), so it remains unfinished. It was never officially named.


2.01 (Buran-class spacecraft), Differences from Buran and Ptichka
The 2.01 is the first of a second series of Buran-class orbiters. Design has been improved using feedback from the earlier models of Buran-class shuttles, such as the flight of Buran and the construction of Ptichka.


2.01 (Buran-class spacecraft), Differences from Buran and Ptichka
After the Challenger disaster it was decided to limit the crew capacity of the second series of orbiters to four crew-members with ejection seats regularly mounted.


2.01 (Buran-class spacecraft), Differences from Buran and Ptichka
Since none of second series orbiters were completed, only changes in thermal protection system and OMS thrusters arrangement can be visible on 2.01.


2.01 (Buran-class spacecraft), History, Projected flights
It was projected in 1989 that orbiter 2.01 would have its first manned space test flight, 3K1, in 1994, with a duration of twenty-four hours. The craft would have been equipped with a life support system and two ejection seats. Crew would have consisted of two cosmonauts — Igor Volk (commander) and Aleksandr Ivanchenko (flight engineer).


2.01 (Buran-class spacecraft), History, Projected flights
In 1991, construction of the orbiter was suspended, and in 1993, the Buran program was completely cancelled.


2.01 (Buran-class spacecraft), History, Post-retirement
After residing at the Tushino factory where it was constructed, it was incorrectly announced in 2006 that orbiter 2.01 would be put on display in the Technik Museum Speyer, Germany. However, the German Museum had actually bought OK-GLI, the jet-powered Buran atmospheric test vehicle, which appeared on display in its own new hangar from September 2008.


2.01 (Buran-class spacecraft), History, Post-retirement
Since 2004 the orbiter 2.01 had been left under open sky on a car park in Moscow, near Khimki Reservoir.


2.01 (Buran-class spacecraft), History, Post-retirement
On 22 June 2011, during the day the orbiter was put on a barge to be moved to the MAKS 2011 international air show, which took place from 16 to 21 August in Zhukovsky (Moscow region). In the night of 22–23 June, it was seen on the Moskva River. The orbiter was exposed at the show with one side restored.


2.01 (Buran-class spacecraft), History, Post-retirement
In 2012, it was seen during the Russian Air Force 100th Anniversary Airshow in Zhukovsky.


2.01 (Buran-class spacecraft), History, Post-retirement
It was expected that it would be restored in Zhukovsky and shown at the MAKS 2013 exhibition, but it never appeared at the exhibition. As of November 2013, it remained at the Zhukovsky International Airport ().


2.01 (Buran-class spacecraft), History, Post-retirement
In July 2017, heat-tiles from orbiter 2.01 were listed online, leading some to believe that the orbiter had been scrapped or otherwise disassembled. However, satellite imagery of Zhukovsky Airport taken in 2019 indicates that 2.01 still resides at the airfield, albeit now in a different location.


2.02 (Buran-class spacecraft)
2.02 (GRAU index serial number 11F35 4K) is the designation of the fourth built Soviet/Russian Buran-class orbiter to be produced as part of the Buran programme.


2.02 (Buran-class spacecraft), History
Construction of 2.02 is believed to begin in 1988. The spacecraft belong to the second series orbiters, whose design has been improved considering experience of flight of K1 Buran.


2.02 (Buran-class spacecraft), History
By 1993, when the Buran program was cancelled, orbiter 2.02 was in an early stage of construction (10-20 percent). Only forward fuselage with crew cabin was completed. The incomplete 2.02 was later partially dismantled at its construction site and moved to the outside of the Tushino Machine Building Plant, near Moscow.


2.02 (Buran-class spacecraft), History
Right wing with landing gear produced for this orbiter was used to complete 0.01 test article, now on display at VDNKh


2.02 (Buran-class spacecraft), History
Some of the tiles from orbiter 2.02 were sold and auctioned on the Internet.


2.03 (Buran-class spacecraft)
2.03 (GRAU index serial number 11F35 5K) is the designation of the fifth Soviet/Russian Buran-class orbiter to be produced as part of the Buran programme. It was never officially named.


2.03 (Buran-class spacecraft)
2.03 was a second series shuttle orbiter, as shown by the '2' in its number. Construction of 2.03 was barely underway when the entire Buran programme was halted in 1993, and as what parts of it had been built were dismantled shortly afterwards. Nothing remained of it by 1995.


2.13.61
2.13.61, Inc. is a publisher and record company founded by musician Henry Rollins and named after his date of birth (February 13, 1961). The company has released albums by the Rollins Band, all of Rollins' spoken word work, and numerous books. It is based in Los Angeles, California.


2.13.61
In his mass-market anthology The Portable Henry Rollins, Rollins stated that he had given 2.13.61 its name because someone had told him that his first self-released book, 20 (1984), had to have a company name on it, and since he felt at the time that he would only ever get to release one book, he simply used his birthdate.


2.13.61
2.13.61 branched out into releasing records not long after Rollins started a solo career following the breakup of Black Flag, initially just releasing Rollins' spoken-word albums. The first two 2.13.61 releases, Big Ugly Mouth and Sweatbox, were first co-released with the label Rollins was signed with at the time as a musician, Texas Hotel Records.


2.13.61
Since then, the label has branched out into various rock and jazz releases and even spawned two specialist reissue sublabels, Infinite Zero Archive (a joint venture with Rick Rubin's American Recordings), and District Line, which specializes in reissuing the music of Rollins' hometown of Washington, D.C. It is also used as the name of Rollins' Blazin' (finishing move) in the video game Def Jam: Fight for NY.


2.13.61
The literary company's authors include: Henry Rollins (Publisher, Black Flag), Iggy Pop (The Stooges), Exene Cervenka (X, Auntie Christ, The Knitters), Nick Cave (Birthday Party, Bad Seeds, Grinderman), Michael Gira (Swans), Joe Cole, Tricia Warden, Don Bajema, Bill Shields, Jeffery Lee Pierce (The Gun Club), and Ellyn Maybe.


2.2.2-Cryptand
[ 2.2.2]Cryptand is the organic compound with the formula N(CH2CH2OCH2CH2OCH2CH2)3N. This bicyclic molecule is the most studied member of the cryptand family of chelating agents. It is a white solid. Many analogous compounds are known. Their high affinity for alkali metal cations illustrates the advantages of "preorganization", a concept within the area of supramolecular chemistry.


2.2.2-Cryptand
For the design and synthesis of [2.2.2]cryptand, Jean-Marie Lehn shared the Nobel Prize in Chemistry. The compound was originally prepared starting with the diacylation of the diamine-diether:


2.2.2-Cryptand
The resulting macrocyclic diamide is reduced by lithium aluminium hydride. The resulting macrocyclic diamine tetraether reacts with a second equivalent of [CH2OCH2COCl]2 to produce the macrobicyclic diamide. This di(tertiary)amide is reduced to the diamine by diborane.


2.2.2-Cryptand
[ 2.2.2]Cryptand binds K+ as an octadentate N2O6 ligand. The resulting cation K([2.2.2]cryptand)+ is lipophilic.


2.2.2-Propellane
[ 2.2.2]Propellane, formally tricyclo[2.2.2.01,4]octane is an organic compound, a member of the propellane family. It is a hydrocarbon with formula C8H12, or C2(C2H4)3. Its molecule has three rings with four carbon atoms each, sharing one C–C bond.


2.2.2-Propellane
This compound is unstable (although not as much as [1.1.1]propellane; however it is less persistent than [1.1.1]propellane). The bond angles on the shared carbons are considerably strained: three of them are close to 90°, the other three to 120°. The strain energy is estimated to be 93 kcal/mol (390 kJ/mol).


2.2.2-Propellane, Synthesis
[ 2.2.2]Propellane was first synthesized in 1973 by the group of Philip Eaton (who had earlier obtained cubane), according to the following scheme:


2.2.2-Propellane, Synthesis
The synthesis begins with photochemical [2+2]cycloaddition of ethylene on the cyclohexene derivative 1 to produce the bicyclic compound 2, followed by elimination reaction with potassium t-butoxide of acetic acid to cyclobutene 3, followed by another cycloaddition with ethylene to 4. This compound is converted to the diazo ketone 5 by deprotonation (using acetic acid and sodium methoxide) and reaction with tosyl azide. The ketone then undergoes Wolff rearrangement to ketene 6. Ozonolysis forms the ketone 7, another  diazotation yields the diazo ketone 8, which undergoes Wolff rearrangement again to the ketene 9. Reaction with dimethylamine affords the [2.2.2]propellane backbone with a dimethylamide substituent 10.


2.2.2-Propellane, Synthesis
The final product 10 was found to spontaneously isomerize in solution to the monocyclic amide 11, with a half-life of 28 minutes at room temperature.


2.2.2-Propellane, Derivatives
A highly fluorinated [2.2.0]propellane was also synthesized by the group of David Lemal.


2.25-Inch Sub-Caliber Aircraft Rocket
The 2.25-Inch Sub-Caliber Aircraft Rocket, or SCAR, was an American unguided rocket developed by the United States Navy during World War II and used for sub-caliber rocket training. Capable of simulating the aerial rockets then coming into operational service, the SCAR was used to train pilots in the use of the new type of weapon, and continued in service throughout the 1950s.


2.25-Inch Sub-Caliber Aircraft Rocket, Development
With the introduction of the 3.5-Inch and 5-Inch Forward Firing Aircraft Rockets, a need arose to train aircraft pilots in the proper tactics for the use of the new weapons. This requirement resulted in the development of a dedicated training rocket by the U.S. Navy.


2.25-Inch Sub-Caliber Aircraft Rocket, Development
Designated 2.25-Inch Sub-Caliber Aircraft Rocket, the resulting rocket was a joint project between the Bureau of Ordnance and the National Defense Research Committee. As its name implied, the rocket was designed as a sub-calibre weapon compared to the FFAR, being only 2.25 inches (57 mm) in diameter, but weighted to be ballistically similar to the larger operational weapons. Varying the amount of propellant in the SCAR's motor could produce accurate simulations of either type of FFAR's flight characteristics.


2.25-Inch Sub-Caliber Aircraft Rocket, Operational history
Following development, SCAR entered full-scale production in January 1945; by July, fully half of the U.S. Navy's rocket production for aircraft use consisted of SCAR rockets. SCAR was widely used during the latter part of World War II as a training round for the FFAR and, later, the High Velocity Aircraft Rocket.


2.25-Inch Sub-Caliber Aircraft Rocket, Operational history
Following the end of the war, it remained in production, continuing in operational service throughout the 1950s. Budget cutbacks prior to the outbreak of the Korean War meant that the SCAR was the only rocket used in training by the majority of pilots.


2.25-Inch Sub-Caliber Aircraft Rocket, Operational history
Despite its small size, SCAR could be hazardous; in 1957, an injury aboard the aircraft carrier USS Kearsarge was caused by the unintended ignition of a SCAR rocket. As recently as 2004, expended SCAR rockets were still occasionally being found in areas that had been used as bombing ranges during World War II.


2.4 GHz radio use
There are several uses of the 2.4 GHz band. Interference may occur between devices operating at 2.4 GHz. This article details the different users of the 2.4 GHz band, how they cause interference to other users and how they are prone to interference from other users.


2.4 GHz radio use, Phone
Many of the cordless telephones and baby monitors in the United States and Canada use the 2.4 GHz frequency, the same frequency at which Wi-Fi standards 802.11b, 802.11g and 802.11n operate. This can cause a significant decrease in speed, or sometimes the total blocking of the Wi-Fi signal when a conversation on the phone takes place. There are several ways to avoid this however, some simple, and some more complicated.


2.4 GHz radio use, Phone
The last will sometimes not be successful, as numerous cordless phones use a feature called Digital Spread Spectrum. This technology was designed to ward off eavesdroppers, but the phone will change channels at random, leaving no Wi-Fi channel safe from phone interference.


2.4 GHz radio use, Bluetooth
Bluetooth devices intended for use in short-range personal area networks operate from 2.4 to 2.4835 GHz. To reduce interference with other protocols that use the 2.45 GHz band, the Bluetooth protocol divides the band into 80 channels (numbered from 0 to 79, each 1 MHz wide) and changes channels up to 1600 times per second. Newer Bluetooth versions also feature Adaptive Frequency Hopping which attempts to detect existing signals in the ISM band, such as Wi-Fi channels, and avoid them by negotiating a channel map between the communicating Bluetooth devices.


2.4 GHz radio use, Bluetooth
The USB 3.0 computer cable standard has been proven to generate significant amounts of electromagnetic interference that can interfere with any Bluetooth devices a user has connected to the same computer.


2.4 GHz radio use, Wi-Fi
Wi-Fi (/ˈwaɪfaɪ/) is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing.


2.4 GHz radio use, Wi-Fi
Devices that can use Wi-Fi technologies include desktops and laptops, video game consoles, smartphones and tablets, smart TVs, digital audio players, cars and modern printers. Wi-Fi compatible devices can connect to the Internet via a WLAN and a wireless access point. Such an access point (or hotspot) has a range of about 20 meters (66 feet) indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points.


2.4 GHz radio use, Wi-Fi
Different versions of Wi-Fi exist, with different ranges, radio bands and speeds. Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5.8 gigahertz (5 cm) SHF ISM radio bands; these bands are subdivided into multiple channels. Each channel can be time-shared by multiple networks. These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s.


2.4 GHz radio use, Wi-Fi
Anyone within range with a wireless network interface controller can attempt to access a network; because of this, Wi-Fi is more vulnerable to attack (called eavesdropping) than wired networks. Wi-Fi Protected Access (WPA) is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time.


2.4 GHz radio use, Wi-Fi
To guarantee no interference in any circumstances the Wi-Fi protocol requires 16.25 to 22 MHz of channel separation (as shown below). The remaining 2 MHz gap is used as a guard band to allow sufficient attenuation along the edge channels. This guardband is mainly used to accommodate older routers with modem chipsets prone to full channel occupancy, as most modern WiFi modems are not prone to excessive channel occupancy.


2.4 GHz radio use, Wi-Fi
While overlapping frequencies can be configured and will usually work, it can cause interference resulting in slowdowns, sometimes severe, particularly in heavy use. Certain subsets of frequencies can be used simultaneously at any one location without interference (see diagrams for typical allocations):


2.4 GHz radio use, Wi-Fi
Most countries Graphical representation of Wireless LAN channels in 2.4 GHz band. Note "channel 3" in the 40 MHz diagram above is often labelled with the 20 MHz channel numbers "1+5" or "1" with "+ Upper" or "5" with "+ Lower" in router interfaces, and "11" as "9+13" or "9" with "+ Upper" or "13" with "+ Lower".


2.4 GHz radio use, Wi-Fi
North America Graphical representation of Wireless LAN channels in 2.4 GHz band. Note "channel 3" in the 40 MHz diagram above is often labelled with the 20 MHz channel numbers "1+5" or "1" with "+ Upper" or "5" with "+ Lower" in router interfaces.


2.4 GHz radio use, Wi-Fi
However, the exact spacing required when the transmitters are not colocated depends on the protocol, the data rate selected, the distances and the electromagnetic environment where the equipment is used.


2.4 GHz radio use, Wi-Fi
The attenuation by relative channel adds to that due to distance and the effects of obstacles. Per the standards, for transmitters on the same channel, transmitters must take turns to transmit if they can detect each other 3 dB above the noise floor (the thermal noise floor is around -101 dBm for 20 MHz channels). On the other hand, transmitters will ignore transmitters on other channels if the attenuated signal strength from them is below a threshold Pth which, for non Wi-Fi 6 systems, is between -76 and -80 dBm.


2.4 GHz radio use, Wi-Fi
While there can be interference (bit errors) at a receiver, this is usually small if the received signal is more than 20 dB above the attenuated signal strength from transmitters on the other channels.


2.4 GHz radio use, Wi-Fi
The overall effect is that if there is considerable overlap between adjacent channels transmitters they will often interfere with each other. However, using every fourth or fifth channel by leaving three or four channels clear between used channels can cause less interference than sharing channels, and narrower spacing still can be used at further distances.


2.4 GHz radio use, ZigBee / IEEE 802.15.4 Wireless Data Networks
Many ZigBee / IEEE 802.15.4-based wireless data networks operate in the 2.4–2.4835 GHz band, and so are subject to interference from other devices operating in that same band. To avoid interference from IEEE 802.11 networks, an IEEE 802.15.4 network can be configured to only use channels 15, 20, 25, and 26, avoiding frequencies used by the commonly used IEEE 802.11 channels 1, 6, and 11.


2.4 GHz radio use, RF peripherals
Some wireless peripherals like keyboards and mice use the 2.4 GHz band with a proprietary protocol.


2.4 GHz radio use, Microwave oven
Microwave ovens operate by emitting a very high power signal in the 2.4 GHz band. Older devices have poor shielding, and often emit a very "dirty" signal over the entire 2.4 GHz band.


2.4 GHz radio use, Microwave oven
This can cause considerable difficulties to Wi-Fi and video  transmission, resulting in reduced range or complete blocking of the signal.


2.4 GHz radio use, Microwave oven
The IEEE 802.11 committee that developed the Wi-Fi specification conducted an extensive investigation into the interference potential of microwave ovens. A typical microwave oven uses a self-oscillating vacuum power tube called a magnetron and a high voltage power supply with a half wave rectifier (often with voltage doubling) and no DC filtering. This produces an RF pulse train with a duty cycle below 50% as the tube is completely off for half of every AC mains cycle: 8.33 ms in 60 Hz countries and 10 ms in 50 Hz countries.


2.4 GHz radio use, Microwave oven
This property gave rise to a Wi-Fi "microwave oven interference robustness" mode that segments larger data frames into fragments each small enough to fit into the oven's "off" periods.


2.4 GHz radio use, Microwave oven
The 802.11 committee also found that although the instantaneous frequency of a microwave oven magnetron varies widely over each half AC cycle with the instantaneous supply voltage, at any instant it is relatively coherent, i.e., it occupies only a narrow bandwidth. The 802.11a/g signal is inherently robust against such interference because it uses OFDM with error correction information interleaved across the carriers; as long as only a few carriers are wiped out by strong narrow band interference, the information in them can be regenerated by the error correcting code from the carriers that do get through.


2.4 GHz radio use, Audio-visual (AV) Devices, Baby monitors
Some Baby monitors use the 2.4 GHz band. Some transmit only audio but others also provide video.


2.4 GHz radio use, Audio-visual (AV) Devices, Audio Devices, Wireless Microphones
Wireless Microphones operate as transmitters. Some digital wireless microphones use the 2.4 GHz band (e.g. AKG model DPT 70).


2.4 GHz radio use, Audio-visual (AV) Devices, Audio Devices, Wireless Speakers
Wireless Speakers operate as receivers. The transmitter is a preamplifier that may be integrated in another device. Some wireless speakers use the 2.4 GHz band, with a proprietary protocol. They may be subject to dropouts caused by interference from other devices.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
Video senders typically operate using an FM carrier to carry a video signal from one room to another (for example, satellite TV or closed-circuit television). These devices typically operate continuously but have low (10 mW) transmit power. However, some devices, especially wireless cameras, operate with (often unauthorized) high power levels, and have high-gain antennas.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
Amateur Radio operators can transmit two-way Amateur television (and voice) in the 2.4 GHz band—and all ISM frequencies above 902 MHz—with maximum power of 1500 watts in the US if the transmission mode does not include spread spectrum techniques. Other power levels apply per regions. In the UK, the maximum power level for a full licence is 400 watts. In other countries, maximum power level for non-spread-spectrum emissions are set by local legislation.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
Although the transmitter of some video cameras appears to be fixed on one frequency, it has been found in several models that the cameras are actually frequency agile, and can have their frequency changed by disassembling the product and moving solder links or dip switches inside the camera.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
These devices are prone to interference from other 2.4 GHz devices, due to the nature of an analog video signal showing up interference very easily. A carrier to noise ratio of some 20 dB is required to give a "clean" picture.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
Continuous transmissions interfere with these, causing "patterning" on the picture, sometimes a dark or light shift, or complete blocking of the signal.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices
Non -continuous transmissions, such as Wi-Fi, cause horizontal noise bars to appear on the screen, and can cause "popping" or "clicking" to be heard in the audio.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices, Wi-Fi networks
Video senders are a big problem for Wi-Fi networks. Unlike Wi-Fi they operate continuously, and are typically only 10 MHz in bandwidth. This causes a very intense signal as viewed on a spectrum analyser, and completely obliterates over half a channel. The result of this, typically in a Wireless Internet service provider-type environment, is that clients (who cannot hear the video sender due to the "hidden node" effect) can hear the Wi-Fi without any issues, but the receiver on the WISP's access point is completely obliterated by the video sender, so is extremely deaf.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices, Wi-Fi networks
Furthermore, due to the nature of video senders, they are not interfered with by Wi-Fi easily, since the receiver and transmitter are typically located very close together, so the capture effect is very high. Wi-Fi also has a very wide spectrum, so only typically 30% of the peak power of the Wi-Fi actually affects the video sender. Wi-Fi is not continuous transmit, so the Wi-Fi signal interferes only intermittently with the video sender.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices, Wi-Fi networks
A combination of these factors - low power output of the Wi-Fi compared to the video sender, the fact that typically the video sender is far closer to the receiver than the Wi-Fi transmitter and the FM capture effect means that a video sender may cause problems to Wi-Fi over a wide area, but the Wi-Fi unit causes few problems to the video sender.


2.4 GHz radio use, Audio-visual (AV) Devices, Video devices, EIRP
Many video senders on the market in the UK advertise a 100 mW equivalent isotropically radiated power (EIRP). However, the UK market only permits a 10 mW EIRP limit. These devices cause far more interference across a far wider area, due to their excessive power. Furthermore, UK video senders are required to operate across a 20 MHz bandwidth (not to be confused with 20 MHz deviation). This means that some foreign imported video senders are not legal since they operate on a 15 MHz bandwidth or lower, which causes a higher spectral power density, increasing the interference. Furthermore, most other countries permit 100 mW EIRP for video senders, meaning a lot of video senders in the UK have excessive power outputs.


2.4 GHz radio use, Radio Control, Toys
Many radio controlled drones, model aircraft, model boats and toys use the 2.4 GHz band.


2.4 GHz radio use, Car alarm
Certain car manufacturers use the 2.4 GHz frequency for their car alarm internal movement sensors. These devices transmit on 2.45 GHz (between channels 8 and 9) at a strength of 500 mW. Because of channel overlap, this will cause problems for channels 6 and 11, which are commonly used default channels for Wi-Fi connections. Because the signal is transmitted as a continuous tone, it causes particular problems for Wi-Fi traffic. This can be clearly seen with spectrum analysers. These devices, due to their short range and high power, are typically not susceptible to interference from other devices on the 2.4 GHz band.


2.4 GHz radio use, Power, Wireless Power
Some new truly wireless power transmission uses the 2.4 GHz band.


2.4 GHz radio use, Resolving interference
Normally interference is not too hard to find. Products are coming onto the market cheaply which act as spectrum analyzers and use a standard USB interface into a laptop, meaning that the interference source can be fairly easily found with a little work, a directional antenna and driving around to find the interference.


2.4 GHz radio use, Resolving interference, Use wires
It is better to use Ethernet or maybe PLC when Wi-Fi can be avoided (but beware of power surges, they may happen through any conductive cable).


2.4 GHz radio use, Resolving interference, Band change
A general strategy for Wi-Fi is to only use the 5 GHz and 6 GHz bands for devices that also support it and to switch off the 2.4 GHz radios in the access points when this band is not needed anymore.


2.4 GHz radio use, Resolving interference, Channel change
Often solving interference is as simple as changing the channel of the offending device. Particularly with video senders, whereby plugging in the receiver with no transmitter attached will let you "see" the neighbour's video sender, this technique is considered part of the "Installation process". Where the channel of one system, such as a Wireless ISP cannot be changed, and it is being Interfered with by something such as a video sender, the owner of the video sender is normally very happy to assist with doing this, providing it is not too much work. However the problem comes when the interference is something such as a wireless CCTV camera which is mounted on a chimney and requires a long ladder to access. Such cameras, due to their height, cause serious problems across a wide area.


2.4 GHz radio use, Resolving interference, Alternative product
Another cure is to offer an alternative product to the owner free of charge. Typically this would be a wired camera, which normally have far better performance than wireless cameras anyway, a cable to replace the video sender, or an alternative video sender which has been hard-wired to an alternative channel, with no means of changing it back to the offending frequency.


2.4 GHz radio use, Resolving interference, Alternative product
Yet another cure is to move from 2.4 GHz to another frequency which lacks the vulnerability to interference inherent at that frequency, for example the 5 GHz frequency for 802.11a/n.


2.4 GHz radio use, Resolving interference, Alternative product
If a device using a proprietary protocol is causing or suffering interference, replacing it with another one using a different communication scheme (proprietary or standard) might solve the problem.


2.4 GHz radio use, Resolving interference, Parameter change
In extreme cases, where the interference is either deliberate or all attempts to get rid of the offending device have proved futile, it may be possible to look at changing the parameters of the network. Changing collinear antennas for high gain directional dishes normally works very well, since the narrow beam from a high gain dish will not physically "see" the interference.


2.4 GHz radio use, Resolving interference, Parameter change
Often sector antennae have sharp "nulls" in their vertical pattern, so changing the tilt angle of sector antennas with a spectrum analyzer connected to monitor the strength of the interference can place the offending device within the null of the sector. High gain antennas on the transmitter end can "overpower" the interference, although their use may cause the effective radiated power (ERP) of the signal to become too high, and so their use may not be legal.


2.4 GHz radio use, Resolving interference, Adding base stations
Interference caused by a Wi-Fi network to its neighbors can be reduced by adding more base stations to that network. Every Wi-Fi standard provides for automatic adjustment of the data rate to channel conditions; poor links (usually those spanning greater distances) automatically operate at lower speeds. Deploying additional base stations around the coverage area of a network, particularly in existing areas of poor or no coverage, reduces the average distance between a wireless device and its nearest access point and increases the average speed.


2.4 GHz radio use, Resolving interference, Adding base stations
The same amount of data takes less time to send, reduces channel occupancy, and gives more idle time to neighboring networks, improving the performance of all networks concerned. However, there is a maximum number of base stations that can be added, after which they disrupt the network more than that they help: any additional capacity is then sapped by control traffic.


2.4 GHz radio use, Resolving interference, Adding base stations
The alternative of increasing coverage by adding an RF power amplifier to a single base station can bring similar improvements to a wireless network. The additional power offered by a linear amplifier will increase the signal-to-noise ratio at the client device, increasing the data rates used and reducing time spent transmitting data. The improved link quality will also reduce the number of retransmissions due to packet loss, further reducing channel occupancy. However, care must be taken to use a highly linear amplifier in order to avoid adding excessive noise to the signal.


2.4 GHz radio use, Resolving interference, Adding base stations
All of the base stations in a wireless network should be set to the same SSID (which must be unique to all other networks within range) and plugged into the same logical Ethernet segment (one or more hubs or switches directly connected without IP routers). Wireless clients then automatically select the strongest access point from all those with the specified SSID, handing off from one to another as their relative signal strengths change. On many hardware and software implementations, this hand off can result in a short disruption in data transmission while the client and the new base station establish a connection. This potential disruption should be factored in when designing a network for low-latency services such as VoIP.


2.4 Metre
The International 2.4mR is a one-person keelboat. The class is a development class governed by the 2.4mR rule. The rule is controlled by World Sailing (ISAF) since it is one of few classes designated as an International class. The class rule is closely related to the 12mR rule that was used in the America's Cup and the shape often resembles the larger sister.


2.4 Metre
While there is a small but active group of amateur designer/builders around the world, around 90% of boats are the commercially produced Norlin Mark III designed by yacht designer Peter Norlin of Sweden. Recently, new designs have come into production, such as the Stradivari III and the Proton.


2.4 Metre
The boat is primarily used for racing and the class holds highly competitive national events in many countries. World and European championships (only when the World Championship is not in Europe) are attracting around 100 boats every year. In some countries, it features mainly as a class for sailors with a disability.


2.4 Metre
The 2.4mR is ideal for adapted sailing since the sailor does not move in the boat, and everything is adjustable from right in front of the sailor. Both hand-steering and foot-steering are possible. The boat's ability in integrated sailing has been proven on the result lists of several World Championships. In 2002 and 2005 there were handicapped World Champions. The boat is sailed without a spinnaker, but with a whisker-pole for the jib.


2.4 Metre, History
After the 1980 America's Cup, people in the Newport, RI area started sailing boats called Mini-12s named for the 12-Metre yachts used in the America's Cup. As the class developed, word of it spread to Sweden, home of yacht designer Peter Norlin. Norlin tweaked the design, and along with other naval architects, he created the 2.4-meter yacht class. Although the 2.4mR is a construction class, Peter Norlin is in practice the totally dominating designer, and the class is therefore often mistaken as a one-design class. In addition to all the sailing aspects of the boat, Norlin has worked the design to incorporate features for the physically disabled to use the boat.


2.4 Metre, One-design
In recent years attempts have been made to develop a one-design class based on the Norlin III. This is primarily because of the need for competition within the Paralympics for racing to be about the sailor and not a technical development race. This led to the introduction of Appendix K to the Class rules and now a group is working on a set of stand-alone One-design rules. This is still at the early stages but it is likely a new one-design class is formed alongside the development class.


2.4 Metre, Rating formula
As an open class rather than a one-design, all boat designs must meet the following formula.


2.4 Metre, Events, Para World Sailing Championships
The 2.4 metre has been used a number of times as equipment for the One-Person Technical Disabled discipline which holds an annual World Championships.


2.4 Metre, Events, Paralympics
Since 2000 the 2.4 Metre has been the official single-crew class boat for sailing at the Summer Paralympics although it has been used in a more one design form utilising the Norlin Mk3 design.


2.43: Seiin High School Boys Volleyball Team
2.43: Seiin High School Boys Volleyball Team (Japanese: 2.43 清陰高校男子バレー部, Hepburn: Nī Ten Yonsan Seiin Kōkō Danshi Barē-bu) is a Japanese volleyball light novel series written by Yukako Kabei and illustrated by Aiji Yamakawa. Shueisha have published five volumes in three seasons since March 2015 under their Shueisha Bunko imprint. A manga adaptation with art by Yamakawa has been serialized in Shueisha's josei manga magazine Cocohana since July 2018. An anime television series adaptation by David Production aired from January 8 to March 26, 2021 on the NoitaminA block.


2.43: Seiin High School Boys Volleyball Team
"2.43" refers to the height of the net for male volleyball, 2.43 m.


2.43: Seiin High School Boys Volleyball Team, Media, Anime
An anime television series adaptation was announced via Twitter on November 1, 2019. The series is animated by David Production and directed by Yasuhiro Kimura, with Yōsuke Kuroda handling series composition, Yūichi Takahashi designing the characters, and Yugo Kanno composing the music. It aired from January 8 to March 26, 2021 on the NoitaminA programming block. The opening theme song is "Paralysis" (麻痺, "Mahi") performed by yama, and the ending theme song is "Undulation" performed by Sōshi Sakiyama (崎山 蒼志, Sakiyama Sōshi). Funimation licensed the series and will stream it on its website in North America and the British Isles, in Europe through Wakanim, and in Australia and New Zealand through AnimeLab.


2.5-millimeter band
The 2.5-millimeter or 122 GHz band is a portion of the EHF (microwave) radio spectrum internationally allocated to amateur radio use between 122.250 GHz and 123.000 GHz.


2.5-millimeter band
The band is close to a molecular resonance of oxygen at 120 GHz, which causes significant atmospheric propagation losses, similar to that found at 60 GHz.


2.5-millimeter band
Due to the lack of commercial off the shelf radios, amateurs who operate on the 2.5 mm band must design and construct their own equipment, and those who do, often attempt to set communication distance records for the band.


2.5-millimeter band, Allocation
The International Telecommunication Union allocates 122.250 GHz and 123.000 GHz to amateur radio on a secondary basis. As secondary users, amateurs must protect the fixed, mobile and inter-satellite services from harmful interference, which share the band with amateurs. In addition, 122 GHz to 123 GHz is an ISM band, and all users must accept interference caused by ISM devices. Amateur satellite operations are not permitted, and the ITU's allocations are the same in all three ITU Regions.


2.5-millimeter band, Distance records
The current world distance record on the 2.5 mm band is 139 kilometres (86 mi) set by stations K6ML, KB6BA and N9JIM on February 17, 2020.


2.5-millimeter band, Distance records
The previous world distance record on the 2.5 mm band was 132 kilometres (82 mi) set by Austrian stations OE5VRL and OE3WOG on October 19, 2013.


2.5-millimeter band, Distance records
The previous United States distance record was 114 kilometres (71 mi) set by stations WA1ZMS and W4WWQ on January 18, 2005.


2.5-millimeter band, Distance records
The longest distance achieved on 2.5 mm in the United Kingdom was 35.9 kilometres (22.3 mi) between stations G8CUB and G0FDZ on April 7, 2021.


2.5-millimeter band, Distance records
In Australia, the 2.5 mm distance record was 69.6 kilometres (43.2 mi) set by stations VK4FB and VK4CSD on July 18, 2019.


2.5D
2.5D (two-and-a-half dimensional, alternatively pseudo-3D or three-quarter) perspective refers to one of two things:


2.5D
By contrast, games, spaces or perspectives not restricted in these ways are said to be true 3D.


2.5D
Common in video games, 2.5D projections have also been useful in geographic visualization (GVIS) to help understand visual-cognitive spatial representations or 3D visualization.


2.5D
The terms three-quarter perspective and three-quarter view trace their origins to the three-quarter profile in portraiture and facial recognition, which depicts a person's face that is partway between a frontal view and a side view.


2.5D, Computer graphics, Axonometric and oblique projection
In axonometric projection and oblique projection, two forms of parallel projection, the viewpoint is rotated slightly to reveal other facets of the environment than what are visible in a top-down perspective or side view, thereby producing a three-dimensional effect. An object is "considered to be in an inclined position resulting in foreshortening of all three axes", and the image is a "representation on a single plane (as a drawing surface) of a three-dimensional object placed at an angle to the plane of projection." Lines perpendicular to the plane become points, lines parallel to the plane have true length, and lines inclined to the plane are foreshortened.


2.5D, Computer graphics, Axonometric and oblique projection
They are popular camera perspectives among 2D video games, most commonly those released for 16-bit or earlier and handheld consoles, as well as in later strategy and role-playing video games. The advantage of these perspectives is that they combine the visibility and mobility of a top-down game with the character recognizability of a side-scrolling game.


2.5D, Computer graphics, Axonometric and oblique projection
Thus the player can be presented an overview of the game world in the ability to see it from above, more or less, and with additional details in artwork made possible by using an angle: Instead of showing a humanoid in top-down perspective, as a head and shoulders seen from above, the entire body can be drawn when using a slanted angle; Turning a character around would reveal how it looks from the sides, the front and the back, while the top-down perspective will display the same head and shoulders regardless.


2.5D, Computer graphics, Axonometric and oblique projection
There are three main divisions of axonometric projection: isometric (equal measure), dimetric (symmetrical and unsymmetrical), and trimetric (single-view or only two sides). The most common of these drawing types in engineering drawing is isometric projection. This projection is tilted so that all three axes create equal angles at intervals of 120 degrees. The result is that all three axes are equally foreshortened. In video games, a form of dimetric projection with a 2:1 pixel ratio is more common due to the problems of anti-aliasing and square pixels found on most computer monitors.


2.5D, Computer graphics, Axonometric and oblique projection
In oblique projection typically all three axes are shown without foreshortening. All lines parallel to the axes are drawn to scale, and diagonals and curved lines are distorted. One tell-tale sign of oblique projection is that the face pointed toward the camera retains its right angles with respect to the image plane.


2.5D, Computer graphics, Axonometric and oblique projection
Two examples of oblique projection are Ultima VII: The Black Gate and Paperboy. Examples of axonometric projection include SimCity 2000, and the role-playing games Diablo and Baldur's Gate.


2.5D, Computer graphics, Billboarding
In three-dimensional scenes, the term billboarding is applied to a technique in which objects are sometimes represented by two-dimensional images applied to a single polygon which is typically kept perpendicular to the line of sight. The name refers to the fact that objects are seen as if drawn on a billboard. This technique was commonly used in early 1990s video games when consoles did not have the hardware power to render fully 3D objects. This is also known as a backdrop.


2.5D, Computer graphics, Billboarding
This can be used to good effect for a significant performance boost when the geometry is sufficiently distant that it can be seamlessly replaced with a 2D sprite. In games, this technique is most frequently applied to objects such as particles (smoke, sparks, rain) and low-detail vegetation. It has since become mainstream, and is found in many games such as Rome: Total War, where it is exploited to simultaneously display thousands of individual soldiers on a battlefield. Early examples include early first-person shooters like Marathon Trilogy, Wolfenstein 3D, Doom, Hexen and Duke Nukem 3D as well as racing games like Carmageddon and Super Mario Kart and platformers like Super Mario 64.


2.5D, Computer graphics, Skyboxes and skydomes
Skyboxes and skydomes are methods used to easily create a background to make a game level look bigger than it really is. If the level is enclosed in a cube, the sky, distant mountains, distant buildings, and other unreachable objects are rendered onto the cube's faces using a technique called cube mapping, thus creating the illusion of distant three-dimensional surroundings. A skydome employs the same concept but uses a sphere or hemisphere instead of a cube.


2.5D, Computer graphics, Skyboxes and skydomes
As a viewer moves through a 3D scene, it is common for the skybox or skydome to remain stationary with respect to the viewer. This technique gives the skybox the illusion of being very far away since other objects in the scene appear to move, while the skybox does not. This imitates real life, where distant objects such as clouds, stars and even mountains appear to be stationary when the viewpoint is displaced by relatively small distances. Effectively, everything in a skybox will always appear to be infinitely distant from the viewer. This consequence of skyboxes dictates that designers should be careful not to carelessly include images of discrete objects in the textures of a skybox since the viewer may be able to perceive the inconsistencies of those objects' sizes as the scene is traversed.


2.5D, Computer graphics, Scaling along the Z axis
In some games, sprites are scaled larger or smaller depending on its distance to the player, producing the illusion of motion along the Z (forward) axis. Sega's 1986 video game Out Run, which runs on the Sega OutRun arcade system board, is a good example of this technique.


2.5D, Computer graphics, Scaling along the Z axis
In Out Run, the player drives a Ferrari into depth of the game window. The palms on the left and right side of the street are the same bitmap, but have been scaled to different sizes, creating the illusion that some are closer than others. The angles of movement are "left and right" and "into the depth" (while still capable of doing so technically, this game did not allow making a U-turn or going into reverse, therefore moving "out of the depth", as this did not make sense to the high-speed game play and tense time limit).


2.5D, Computer graphics, Scaling along the Z axis
Notice the view is comparable to that which a driver would have in reality when driving a car. The position and size of any billboard is generated by a (complete 3D) perspective transformation as are the vertices of the poly-line representing the center of the street. Often the center of the street is stored as a spline and sampled in a way that on straight streets every sampling point corresponds to one scan-line on the screen. Hills and curves lead to multiple points on one line and one has to be chosen.


2.5D, Computer graphics, Scaling along the Z axis
Or one line is without any point and has to be interpolated lineary from the adjacent lines. Very memory intensive billboards are used in Out Run to draw corn-fields and water waves which are wider than the screen even at the largest viewing distance and also in Test Drive to draw trees and cliffs.


2.5D, Computer graphics, Scaling along the Z axis
Drakkhen was notable for being among the first role-playing video games to feature a three-dimensional playing field. However, it did not employ a conventional 3D game engine, instead emulating one using character-scaling algorithms. The player's party travels overland on a flat terrain made up of vectors, on which 2D objects are zoomed. Drakkhen features an animated day-night cycle, and the ability to wander freely about the game world, both rarities for a game of its era. This type of engine was later used in the game Eternam.


2.5D, Computer graphics, Scaling along the Z axis
Some mobile games that were released on the Java ME platform, such as the mobile version of Asphalt: Urban GT and Driver: L.A. Undercover, used this method for rendering the scenery. While the technique is similar to some of Sega's arcade games, such as Thunder Blade and Cool Riders and the 32-bit version of Road Rash, it uses polygons instead of sprite scaling for buildings and certain objects though it looks flat shaded. Later mobile games (mainly from Gameloft), such as Asphalt 4: Elite Racing and the mobile version of Iron Man 2, uses a mix of sprite scaling and texture mapping for some buildings and objects.


2.5D, Computer graphics, Parallax scrolling
Parallaxing refers to when a collection of 2D sprites or layers of sprites are made to move independently of each other and/or the background to create a sense of added depth. This depth cue is created by relative motion of layers. The technique grew out of the multiplane camera technique used in traditional animation since the 1940s. This type of graphical effect was first used in the 1982 arcade game Moon Patrol. Examples include the skies in Rise of the Triad, the arcade version of Rygar, Sonic the Hedgehog, Street Fighter II, Shadow of the Beast and Dracula X Chronicles, as well as Super Mario World.


2.5D, Computer graphics, Mode 7
Mode 7, a display system effect that included rotation and scaling, allowed for a 3D effect while moving in any direction without any actual 3D models, and was used to simulate 3D graphics on the SNES.


2.5D, Computer graphics, Ray casting
Ray casting is a first person pseudo-3D technique in which a ray for every vertical slice of the screen is sent from the position of the camera. These rays shoot out until they hit an object or wall, and that part of the wall is rendered in that vertical screen slice. Due to the limited camera movement and internally 2D playing field, this is often considered 2.5D.


2.5D, Computer graphics, Bump, normal and parallax mapping
Bump mapping, normal mapping and parallax mapping are techniques applied to textures in 3D rendering applications such as video games to simulate bumps and wrinkles on the surface of an object without using more polygons. To the end user, this means that textures such as stone walls will have more apparent depth and thus greater realism with less of an influence on the performance of the simulation.


2.5D, Computer graphics, Bump, normal and parallax mapping
Bump mapping is achieved by perturbing the surface normals of an object and using a grayscale image and the perturbed normal during illumination calculations. The result is an apparently bumpy surface rather than a perfectly smooth surface although the surface of the underlying object is not actually changed. Bump mapping was introduced by Blinn in 1978.


2.5D, Computer graphics, Bump, normal and parallax mapping
In normal mapping, the unit vector from the shading point to the light source is dotted with the unit vector normal to that surface, and the dot product is the intensity of the light on that surface. Imagine a polygonal model of a sphere—you can only approximate the shape of the surface. By using a 3-channel bitmapped image textured across the model, more detailed normal vector information can be encoded. Each channel in the bitmap corresponds to a spatial dimension (x, y and z).


2.5D, Computer graphics, Bump, normal and parallax mapping
These spatial dimensions are relative to a constant coordinate system for object-space normal maps, or to a smoothly varying coordinate system (based on the derivatives of position with respect to texture coordinates) in the case of tangent-space normal maps. This adds much more detail to the surface of a model, especially in conjunction with advanced lighting techniques.


2.5D, Computer graphics, Bump, normal and parallax mapping
Parallax mapping (also called offset mapping or virtual displacement mapping) is an enhancement of the bump mapping and normal mapping techniques implemented by displacing the texture coordinates at a point on the rendered polygon by a function of the view angle in tangent space (the angle relative to the surface normal) and the value of the height map at that point. At steeper view-angles, the texture coordinates are displaced more, giving the illusion of depth due to parallax effects as the view changes.


2.5D, Film and animation techniques
The term is also used to describe an animation effect commonly used in music videos and, more frequently, title sequences. Brought to wide attention by the motion picture The Kid Stays in the Picture, an adaptation of film producer Robert Evans's memoir, it involves the layering and animating of two-dimensional pictures in three-dimensional space. Earlier examples of this technique include Liz Phair's music video "Down" (directed by Rodney Ascher) and "A Special Tree" (directed by musician Giorgio Moroder).


2.5D, Film and animation techniques
On a larger scale, the 2018 movie In Saturn's Rings used over 7.5 million separate two-dimensional images, captured in space or by telescopes, which were composited and moved using multi-plane animation techniques.


2.5D, Graphic design
The term also refers to an often-used effect in the design of icons and graphical user interfaces (GUIs), where a slight 3D illusion is created by the presence of a virtual light source to the left (or in some cases right) side, and above a person's computer monitor. The light source itself is always invisible, but its effects are seen in the lighter colors for the top and left side, simulating reflection, and the darker colours to the right and below of such objects, simulating shadow.


2.5D, Graphic design
An advanced version of this technique can be found in some specialised graphic design software, such as Pixologic's ZBrush. The idea is that the program's canvas represents a normal 2D painting surface, but that the data structure that holds the pixel information is also able to store information with respect to a z-index, as well material settings, specularity, etc. Again, with this data it is thus possible to simulate lighting, shadows, and so forth.


2.5D, History
The first video games that used pseudo-3D were primarily arcade games, the earliest known examples dating back to the mid-1970s, when they began using microprocessors. In 1975, Taito released Interceptor, an early first-person shooter and combat flight simulator that involved piloting a jet fighter, using an eight-way joystick to aim with a crosshair and shoot at enemy aircraft that move in formations of two and increase/decrease in size depending on their distance to the player.


2.5D, History
In 1976, Sega released Moto-Cross, an early black-and-white motorbike racing video game, based on the motocross competition, that was most notable for introducing an early three-dimensional third-person perspective. Later that year, Sega-Gremlin re-branded the game as Fonz, as a tie-in for the popular sitcom Happy Days.


2.5D, History
Both versions of the game displayed a constantly changing forward-scrolling road and the player's bike in a third-person perspective where objects nearer to the player are larger than those nearer to the horizon, and the aim was to steer the vehicle across the road, racing against the clock, while avoiding any on-coming motorcycles or driving off the road.


2.5D, History
That same year also saw the release of two arcade games that extended the car driving subgenre into three dimensions with a first-person perspective: Sega's Road Race, which displayed a constantly changing forward-scrolling S-shaped road with two obstacle race cars moving along the road that the player must avoid crashing while racing against the clock, and Atari's Night Driver, which presented a series of posts by the edge of the road though there was no view of the road or the player's car. Games using vector graphics had an advantage in creating pseudo-3D effects. 1979's Speed Freak recreated the perspective of Night Driver in greater detail.


2.5D, History
In 1979, Nintendo debuted Radar Scope, a shoot 'em up that introduced a three-dimensional third-person perspective to the genre, imitated years later by shooters such as Konami's Juno First and Activision's Beamrider. In 1980, Atari's Battlezone was a breakthrough for pseudo-3D gaming, recreating a 3D perspective with unprecedented realism, though the gameplay was still planar. It was followed up that same year by Red Baron, which used scaling vector images to create a forward scrolling rail shooter.


2.5D, History
Sega's arcade shooter Space Tactics, released in 1980, allowed players to take aim using crosshairs and shoot lasers into the screen at enemies coming towards them, creating an early 3D effect. It was followed by other arcade shooters with a first-person perspective during the early 1980s, including Taito's 1981 release Space Seeker, and Sega's Star Trek in 1982. Sega's SubRoc-3D in 1982 also featured a first-person perspective and introduced the use of stereoscopic 3-D through a special eyepiece. Sega's Astron Belt in 1983 was the first laserdisc video game, using full-motion video to display the graphics from a first-person perspective. Third-person rail shooters were also released in arcades at the time, including Sega's Tac/Scan in 1982, Nippon's Ambush in 1983, Nichibutsu's Tube Panic in 1983, and Sega's 1982 release Buck Rogers: Planet of Zoom, notable for its fast pseudo-3D scaling and detailed sprites.


2.5D, History
In 1981, Sega's Turbo was the first racing game to feature a third-person perspective, rear view format. It was also the first racing game to use sprite scaling with full-colour graphics. Pole Position by Namco is one of the first racing games to use the trailing camera effect that is now so familiar. In this particular example, the effect was produced by linescroll—the practice of scrolling each line independently in order to warp an image. In this case, the warping would simulate curves and steering. To make the road appear to move towards the player, per-line color changes were used, though many console versions opted for palette animation instead.