<P> In mid-September 2016, concept art seen during the media's set indicated Midgard Serpent and The Broker, previously played by Christopher Fairbank in Guardians of the Galaxy, would appear, and that Sif and the Warriors Three, allies of Thor in the previous two films, would be addressed in Ragnarok . Towards the end of the month, Sam Neill, who worked with Waititi in Hunt for the Wilderpeople, revealed he had a role in the film . Shortly after, Waititi teased the inclusion of the character Korg in the film, who Waititi portrays through motion - capture . In mid-October, Waititi revealed that new camera technology had been used for a shot in the film, and that he had hoped to include John C. Reilly's Nova Corpsman Rhomann Dey in the film, but there was "no real way to pull it off ." Principal photography wrapped on October 28, 2016, with Waititi also revealing that the character Miek would appear in the film, who is not portrayed by an actor in the film, as he does not speak, and is depicted as "a larva - like creature...(with) cybernetic legs and arms ." </P> <P> According to Waititi, 80 percent of the dialogue in Thor: Ragnarok was improvised, in order to create a "very loose and collaborate mood" among the cast and an attempt to replicate the tone and sensibility from his previous films . He stated, "My style of working is I'll often be behind the camera, or right next to the camera yelling words at people, like,' Say this, say this! Say it this way!"' </P> <P> In February 2017, Rachel House said she had a small role in the film, having worked with Waititi before . Additional filming took place in Atlanta in July 2017, over three weeks, including filming the film's post-credit scenes . Updated writing credits for the film were also revealed, with Pearson credited as the screenwriter as well as receiving story credit with Kyle and Yost, who were credited as a writing team . Folsom took issue to Marvel releasing a poster and trailer with these credits, noting the Writers Guild of America (WGA) had yet to determine the final credits for the film . At the end of July, Waititi said that he had also provided the motion - capture performance for Surtur, and that Clancy Brown would provide the voice for that character in the film . In September 2017, Folsom expanded on the film's writing credits, noting that Marvel had given her a story credit on the film, but was denied by the WGA due to their regulation that a maximum of two individuals can receive story credit, with an allowance for a writing team to count as one individual; Pearson and the team of Kyle and Yost received the story credit on Ragnarok . Folsom added that she planned to appeal the decision, and that Marvel has been supportive of her throughout her attempt to receive credit . By the end of the month, the writing credits were updated once again, this time removing the story credits and giving Pearson, Kyle, and Yost the screenwriting credit . Additionally, Tadanobu Asano was confirmed to be reprising his role of Hogun in the film . </P> <P> Visual effects for the film were created by: Industrial Light & Magic's (ILM) San Francisco and Vancouver studios, with help from Base FX, Animatrik, and Virtuos; Framestore; Method Studios Vancouver; Digital Domain; Rising Sun Pictures; Luma Pictures; D Negative; Iloura; Image Engine; Trixter; The Secret Lab; WhiskeyTree Inc; Fin Designs + Effects; and Perception . Previsualization work was provided by The Third Floor and Day for Nite . To help create the Hulk, a person on set was covered in green body paint, and would replicate the intended motions of the character to aid the visual effect artists . </P>

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