The Magic Behind Creating the CGI Na’vi Characters in AVATAR

AVATAR was a visual feast thanks to its CGI characters exhibiting lifelike characteristics and expressions. Although animation played the major role in getting the look of the movie just right, the job was made significantly easier through the use of innovative filming techniques. This article looks at the innovations that James Cameron used when making AVATAR.

Guest post by Karishma Sundaram

James Cameron is known for his revolutionary filming techniques, and each time he makes a movie, the bar is raised a little more. The case is certainly no different with AVATAR which was created with a combination of live action filming and computer generated imagery (CGI) to create a visual masterpiece. There was also use of live backgrounds, interspersed liberally with computer-generated ones.

The filmmaking was a carefully planned, step-by-step process, starting with live action filming, and then going back and forth between that and CGI, to finally arrive at the finished product. According to Cameron, only 40% of the film was live action, while the rest was entirely CGI and miniatures.

Motion-capture Photography

The filming first began with the non-critical parts of the movie. This was done in preparation for the animation work, as the two were combined at a later stage.

The second stage included the use of motion-capture photography. This meant that the actors played their roles in front of a camera, used specifically to capture their movements and expressions. This captured imagery was then taken into an animation studio and applied onto the CGI characters of the Na’vi.

The revolutionary part of this technique was the special augmented reality camera that the director used. Although the actors interacted with thin air during scenes with animated backgrounds, the director was able to use the special camera to view the captured footage on a screen with the animated background already in place. Therefore, as the actors played out their roles, Cameron was able to direct their movements while referencing the animated background.

The technique significantly reduced effort, on the parts of the actors, as there was no requirement to break the flow repeatedly. Also with the augmented reality camera, the director had the freedom to change the background as often as he chose to, adding an incredible level of flexibility to the filmmaking process.

Interaction Between CGI and the Actors

When live action actors interacted with CGI characters, the technique used was slightly different. A small camera was used instead of the augmented reality camera and in addition to the HD 3D cameras. This device, dubbed Simul-cam, is actually a combination of both technologies, and produces a similar working environment as the augmented reality camera. The actors and the CGI characters were able to interact easily with each other, as the director is able to see the actors in the virtual environment and direct them accordingly.

Facial Expressions

One of the most truly incredible parts of AVATAR was the realistic expressions on the faces of the CGI characters. This was accomplished through the use of skullcaps, fitted tightly over the actors’ heads, and an attached camera positioned directly in front.

The camera captured the visual representation of the expressions, while the skullcaps recorded the movement of the facial muscles. Using both sets of data in conjunction, animators were able to transfer the expression perfectly onto the CGI counterparts.

In the extended footage of the movie, the crew commented on the most difficult scene of the whole movie: the one were Neytiri, as a Na’vi, and Jake Sully, as a human, are actually touching onscreen. The logistics of that scene included calculating the shadows of both characters as they related to each other. While this is difficult in the case of just CGI, the combination of live action and CGI made it even more arduous.

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Were you ever aware of the computer graphics in the actors expressions or was the experience seamless?

Comments

[Marali]

It was pretty realistic....in fact, it was so realistic that I now write off any alien made after 2010 as well, nothing special. Serioulsy, we could see sweat, pores and even veins on the Na'vi!