[Figure 10] Eye-texture map.

Eyes
Eyes represent the life force behind believable computer graphics creatures and characters. Every director and supervisor on the projects I have worked on has concentrated a great deal of energy and attention on the eyes of CG characters. There are several methods for ensuring that the audience notices the eyes and believes there is life and energy behind them. We look people in the eye every day during conversations and interactions, so we have a great deal of experience with how eyes should look. You may not be able to explain that a glisten is missing from the caruncula lacrymalis (the fleshy area on the inner angle of the eye), but the lifeless eye is noticed. Textures
A believable eye begins with a high-quality texture (see Figure 10). The texture shown here has a reasonable amount of detail in the cornea (the orange section), as well as some vein detail in the whites of the eyes. The distortion of this texture (the black at the top represents the pupil) is the result of a square image for the spherical map corresponding to the shape of an eyeball. A great deal of reference study is invested in the construction of eyes and in the painting of their textures. Depending on how close the character or creature comes to the camera, details such as individual red blood vessels in the whites of the eyes are added or ignored.

The lighting and reflections also play an important role in the look of the eyes on a CG character or creature. Reflections in eyes, because they are a smooth, wet, shiny surface, are sometimes quite distinctive. If the eyes come close to the camera, an identifiable shape, such as a window, light fixture or cloud can add a great deal of realism to the character (see Figure 11). A particular reflection can be added to the eye with a special environment texture map. The sky and clouds here were specifically chosen and oriented to be distinctive on the character’s eyes.

[Figure 11] A sky with clouds reflected in the character’s eyes.

[Figure 12] Specular highlights in the character’s eyes.

Specular Highlights
Although reflections are important, every special effects supervisor I have ever worked with has asked specifically to see specular highlights on the eyes of characters and creatures. It has long been standard procedure to use special eye lights on close-ups of live actors to accentuate their performance. To blend CG characters into the film requires the same treatment. These lights can be placed fairly close to the eyes, and often a separate one is created for each eye. The light should be a specular-only light, and can be roughly located with the specular information offered in the hardware render window, before fine-tuning the location in the rendered image (see Figure 12). The specular highlights on the eyes are usually small and tight, once again because of the wet, shiny and smooth surface of the eyeball. Parameters for the size of the specular highlight can be adjusted in the light.