Silhouette-Opaque Transparency Rendering

Transparency in 3D graphics has traditionally been created by ordering the transparent objects from back-to-front with respect to the viewpoint, and rendering the opaque objects first and then the transparent objects in the prescribed order. This has three major disadvantages: need for splitting intersecting polygons, repeated ordering for varying view points, and finally, incorrect transparency at the regions near silhouettes. The first two problems are eliminated by order independent transparency rendering techniques. The goal of this paper is to eliminate the third disadvantage also. Silhouettes look more opaque than the rest of the regions of the model. We call this silhouette-opaque transparency rendering. We use the alpha value as a probabilistic measure, similar to other order independent methods. We differ from the traditional methods by using this probabilistic measure in object space rather than in image space to render the transparency in silhouettes correctly. We call our technique to achieve silhouette-opacity as object-space screen-door transparency.