(Avatar Physics and Genetics)
5. Visualization
With this approach, avatars are seen as synthetic personas that lie outside of reality, yet refer to our reality, in a stylized manner, where some things are left out, and other things are exaggerated. For instance, eyes are a little larger than normal, ge-netic variation is extreme, and walking motions are exaggerated. To represent ava-tars visually, a cartoon-style outline renderer is used. It displays 3D polygonal mod-els with flat-shading and outlines.
The outline renderer displays lines only on the silhouette, or horizon edges. The avatar head shown in Figure 8a is drawn without the outline renderer eliminating non-silhouette edges, to show a contrast to the faces shown in previous figures, which demonstrate the effect of the outline renderer. The outline renderer only dis-plays the edges whose shared triangles lie such that their surface normals satisfy the following condition: One surface normal (A) points towards the viewpoint, and the other (B) points away (determined by calculating the dot product of the line of sight with each normal), as indicated in Figure 8b.
Fig. 8. a) Facial geometry showing all edges, b) silhouette edge detection
5.1 Level of Detail
An important aspect of the avatar design, as is true with the design of any object in a virtual world, is Level of Detail. At any given time, an avatar is rendered using one of many possible levels of detail - as dictated by the distance from the viewpoint to the avatar. Each of these rendering levels has been designed separately. Level of detail in an online community takes on a more complex meaning when it includes not just mere viewing distance, but also "importance" in a given situation, as well as crowd considerations.
Conclusion, Acknowledgements, and References
