Optics principles. For example, the Ames room, Hering, Müller-Lyer, Orbison, Ponzo, Sander, and Wundt illusions all rely on the suggestion of the appearance of distance by using converging and diverging lines, in the same way that parallel light rays (or indeed any set of parallel lines) appear to converge at a vanishing point at infinity in two-dimensionally rendered images with artistic perspective. This suggestion is also responsible for the famous moon illusion where the moon, despite having essentially the same angular size, appears much larger near the horizon than it does at zenith. This illusion so confounded Ptolemy that he incorrectly
Point-to-Point Protocol daemon also capable of handling Dial-on-demand routing, where pppd sets up a virtual network, captures the packages it receives and establishes a PPP connection and forwards the captured and not-yet transmitted packages over the link. Point-to-Point Protocol daemon PPPD is the Point-to-Point Protocol daemon which is used to manage network connections between two nodes on Unix-like operating systems. It is configured using command-line arguments and configuration files. While it has initially been used to manage only dial-up access, it is also used to manage broadband connections such as DSL, if Point-to-Point Protocol over Ethernet (PPPoE) or Point-to-Point Protocol over ATM (PPPoA)