Pirates of the Caribbean: On Stranger Tides film provided him a long-awaited opportunity to work with Depp, and that his directing was helped by his experience as a choreographer—"the action sequences felt like big production numbers." On September 11, 2009, at Disney's D23 convention during a Disney event, Cook and Johnny Depp, in full Captain Jack Sparrow costume, announced that a fourth "Pirates" film was in development. The title was announced as "Pirates of the Caribbean: On Stranger Tides". Marshall visited the Pirates of the Caribbean ride in Disneyland for inspiration, eventually paying homage with a skeleton holding a magnifying glass in Ponce de León's ship. An
Pirates of the Caribbean: On Stranger Tides at the 007 Stage on Pinewood. "On Stranger Tides" employed 1,112 shots of computer-generated imagery, which were done by ten visual effects companies. Cinesite visual effects supervisor Simon Stanley-Clamp claimed that the most difficult part was doing the effects in 3D: "Rotoscoping is tricky. Cleaning up plates is double the work, and tracking has to be spot on." The lead companies, with over 300 effects each, were Industrial Light & Magic—responsible for, among others, the mermaids and most water effects—and Moving Picture Company, who created digital ships and environment extensions, such as changing weather and designing cliffs and waterfalls. Filming