Andy Serkis was wary of making his 'Planet of the Apes' alter ego Caesar "too human-like".
The 53-year-old actor provided his exceptional motion capture skills for the intelligent chimpanzee in the trilogy of rebooted movies based on the popular sci-fi film franchise which began with 1968's Charlton Heston-led film that was based on French author Pierre Boulle's 1963 novel 'La Planète des Singes'.
The movies 'Dawn of the Planet of the Apes' and 'War for the Planet of the Apes' were directed by Matt Reeves and Serkis has revealed he and the filmmaker were constantly refining the script for the final film ensuring that Caesar still very much identified as an ape despite his intelligence, speech and evolution.
Speaking to Den of Geek, Serkis said: "Linguistically we always had to make sure it didn't tip over the edge and become too casual.
"He [Caesar] had to speak faster and be more eloquent, in a more reflective and philosophical way, but Matt and I were always refining the script to ensure it didn't sound too human-like. At times on the page it just fell off the tightrope and sounded like a guy having a conversation so we had to work hard on that."
Serkis, 53, kick-started his motion capture career by portraying Gollum in Peter Jackson's 'Lord of the Rings' trilogy and has since gone on to create The Imaginarium Studios production company with producer Jonathan Cavendish which specialises in Performance Capture technology.
The British actor insists there is no difference between portraying a character via the use of CGI to doing it in person in front of the cameras.
He said: "Performance capture is no different to any kind of acting. It's not a special type of acting. The performance you see in the camera on the day is what you get but translated into the physiognomy of the character. What Matt does with the performance is, say he's shooting a scene with me and Woody Harrelson, he lives for months with my face in the edit, cutting the drama between me and Woody until seven or eight months down the line that he'll get visual effects shots.
"That's when he'll put Caesar next to my performance and say, 'Andy is feeling rage and vulnerability and isn't sure what he's going to do, but I only see rage in Caesar so let's refine it.'
"Every single shot become closer through a process of iteration, sometimes a 120 versions of the same shot."
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