Realtime Painterly Rendering for Animation

This paper describes a realtime system for rendering animations in a painterly style. Impressionistic images are created using a large quantity of brush strokes, organized in particle systems to achieve frame-to-frame coherence. Reference pictures are used to compute the properties of each stroke. The basis of the presented technique is [Meier, B. J.: Painterly Rendering for Animation. In: Proceedings of SIGGRAPH 96, p. 477–484, 1996], which describes a system for offline-rendering. The system presented there was modified for being applicable in realtime environments by extensive use of modern 3D hardware. The possibility to send instructions to the graphics card and execute them either per vertex or per pixel—using vertex and pixel shaders—allows both the rendering of thousands of brush strokes per frame, and the correct application of their properties. Programming the graphics hardware is done with the high level shading language Cg. Fast access to reference pictures is achieved by using OpenGL extensions that allow direct rendering to textures. The results are very promising. Although not all aspects of the original painterly algorithm were included, the rendered images provide an idea of what is possible using this technique. With a few more optimization steps it should be possible to utilize the presented technique in complex environments.