Comparing Perception of Animated Imposters and 3D Models

Abstract: In modern 3D games and movies, large character crowds are commonly rendered which can be expensive with regard to rendering times. As character complexity increases, so does the need for optimizations. Level of Detail (LOD) techniques are used to optimize rendering by reducing geometric complexity in a scene. One such technique is reducing a complex character to a textured flat plane, a so called imposter. Previous research has shown that imposters are a good way of optimizing 3D-rendering, and can be done without decreasing visual fidelity compared to 3D-models if rendered statically up to a one- to-one pixel to texel ratio. In this report we look further into using imposers as an LOD technique by investigating how animation, in particular rotation, of imposters at different distances affects human perception when observing character crowds. The results, with regards to static non rotating characters, goes in line with previous research showing that imposters are indistinguishable from 3D-models when standing still. When introducing rotation, slow rotation speed is shown to be a dominant factor compared to distance which reveals crowds of imposters. On the other hand, the results suggest that fast movements could be used as a means for hiding flaws in pre-rendered imposters, even at near distances, where non moving imposters otherwise could be distinguishable.