(Avatar Physics and Genetics)

3. Genetics

Parametric representations naturally lend themselves to a genetic interpretation. The design methodology of the avatar includes identifying variations in the parameters used in the computer code, setting ranges for these parameters, and placing them into an array, which can be manipulated in a variety of ways. This array is called the genotype, and every avatar has one.

3.1 Genotype
The genotype consists of an array of values that determine various attributes of an avatar. The gene ranges provide an overall genetic space within which all possible avatars can exist. While some of the remote regions of this genetic space are occu-pied by some freaky-looking monsters, the space is largely occupied by reasonable-looking humanoids. Figure 4 shows five ethnic types, each existing within the ge-netic space.





Fig. 4. Avatar faces showing genetic variety

3.2 Genetic Customization
Figure 5 shows some examples of avatar faces that were made with the Genetic Customization Tool. With this tool, one can manipulate about 60 of the more than 100 genes which describe an avatar. These genes affect body shapes, colors, motions, facial proportions, and walking styles. The number of genes and the manner in which they interact, is such that many possible avatars can be generated within one system.

The Genetic Customization Tool allows users to interactively tweak genes in a continuous manner and to see the changes in real time. This is done "online" within the virtual world with physics continually running. One does not have to remove the avatar from the world and place it into a separate application. While customizing, one can rotate the avatar and move the camera closer to the face or away to see the whole body. This interface is similar to the real-time genetic tweakers used in two previous research projects: the Character Evolution Tool [6] and Darwin Pond, [7] (www.ventrella.com).




Fig.5. Progressive mutations of an avatar

With this genetic representation of avatars in place, it is possible to later apply genetic operators and use a variety of genetic manipulations, including cross-over from sexual reproduction.



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4. Social Aspects

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