Polypostors: 2D Polygonal Impostors for 3D Crowds

Ladislav Kavan Simon Dobbyn Steven Collins Jiří Žára Carol O'Sullivan
Proceedings of ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games, pp. 149-155, 2008
Various methods have been proposed to animate and render large crowds of humans in real time for applications such as games and interactive walkthroughs. Recent methods have been developed to render large numbers of pre-computed image-based human representations (Impostors) by exploiting commodity graphics hardware, thus achieving very high frame-rates while maintaining visual fidelity. Unfortunately, these images consume a lot of texture memory, no in-betweening is possible, and the variety of animations that can be shown is severely restricted. This paper proposes an alternative method that significantly improves upon pre-computed impostors: automatically generated 2D polygonal characters (or Polypostors). When compared with image-based crowd rendering systems, Polypostors exhibit a similarly high level of rendering efficiency and visual fidelity, with considerably lower memory requirements (up to a factor of 30 in our test cases). Furthermore, Polypostors enable simple in-betweening and can thus deliver a greater variety of animations at any required level of smoothness with almost no overhead.