Nick Davis, VFX supervisor on CGI-live-action hybrid “The One and Only Ivan,” helped director Thea Sharrock answer the question, “How are we going to make a movie where the principal actors don’t exist?”

Adapted from Katherine Applegate’s novel of the same name, the film — streaming Aug. 21 on Disney Plus — revolves around the titular gorilla (voiced by Sam Rockwell), who lives in captivity in a mall along with other animals, including an elephant named Stella (Angelina Jolie) and baby elephant Ruby (Brooklynn Prince of “The Florida Project”). 

Ivan has a knack for painting and drawing, and he brings attention to his art in an attempt to show people he needs to be free. Bryan Cranston plays Mack, the owner of Big Top Mall, which features the animals in a circus-like attraction. 

Davis mapped out a workflow that allowed “Me Before You” helmer Sharrock to bring the virtual characters to life, from positioning them with the live actors all the way through to layering on the finishing CG touches. 

In the primary step of the process, Cranston, Ramón Rodríguez (mall cleaner George) and Ariana Greenblatt (George’s daughter, Julia) were filmed in real-world locations such as the mall, the animal enclosure and the circus performance area. “That would enable the actors to perform traditionally,” Davis explains. Since the animals didn’t exist in any form at that point, puppeteers were used to represent Ivan and the key animated characters, allowing the actors to have an eyeline to play their scenes. 

“But it also allowed the camera crew to shoot in a very traditional method,” Davis says. “They could see what they needed to see for the shot, and later we could replace all of that and put the CG animals in there.”

The second step of the process, motion capture, involved tackling the 50 pages of the screenplay that featured the animals only. The cast prerecorded all their voice performances, and the mo-cap actors mimed their actions accordingly. “We went onto the virtual set where Thea could use a virtual reality headset and plan out her shots and best angles,” Davis says. “We were able to pass on these master scenes as motion-capture data to the VFX company MPC, and [they] could animate the clips.” The composites were returned two months later as “master scene clips.”  

With the master scene clips in hand, it was back to the virtual stage. Using the Unity game engine, the film’s DP, Florian Ballhaus (“Men in Black”), and his camera team focused in on the parts of the scenes to highlight, using real-world film skills to pan-and-scan, then chose dolly, crane or handheld shots, for example, while assessing their work on monitors. Additionally, lighting choices were made by use of key lights, brightness levels and color temperature. “We could shoot and light those scenes in the virtual world using the master clips,” Davis says. 

The dailies came together and the CG artists got their turn, using in-house software that allowed them to simulate things like hair, skin and feathers (for the character of a chicken), as well as how light and shadow would bounce off each hair. “It was that level of technical detail that has been put into the creation of each of the animals that really starts to give them that incredibly photorealistic look,” Davis says. “We wanted our animals to look like animals.”