Editing Crowd simulation (section)

== Crowd rendering and animation ==
Rendering and animating a large number of agents realistically, especially in real time, is challenging. To reduce the complexity of 3D rendering of large-scale crowds, techniques like culling (discarding unimportant objects), impostors (image-based rendering) and decreasing levels of detail have been used.<ref>{{cite journal |doi=10.1109/76.825720 |title=Real-time display of virtual humans: Levels of details and impostors |journal=IEEE Transactions on Circuits and Systems for Video Technology |volume=10 |issue=2 |pages=207–17 |year=2000 |last1=Aubel |first1=A. |last2=Boulic |first2=R. |last3=Thalmann |first3=D. }}</ref>
Variations in appearance, body shape and size, accessories and behavior (social or cultural) exist in real crowds, and lack of variety affects the realism of visual simulations. Existing systems can create virtual crowds with varying texture,<ref name="Maim et al 2009"/> color,<ref>{{cite book |last1=Gosselin |first1=David R. |last2=Sander |first2=Pedro V. |last3=Mitchell |first3=Jason L. |chapter=Drawing a Crowd |editor1-first=Wolfgang |editor1-last=Engel |title=ShaderX3: Advanced Rendering Techniques in DirectX and OpenGL |url=https://archive.org/details/shaderxadvancedr00enge_759 |url-access=limited |publisher=Charles River Media |location=Cambridge, MA |year=2004 |pages=[https://archive.org/details/shaderxadvancedr00enge_759/page/n498 505]–17 |isbn=978-1-58450-357-6 }}</ref> size, shape and animation.<ref name="Thalmann et al 2009"/>