Non-Photorealistic Computer Graphics Library

Hatching, Stroke Styles & Pointillism

Author(s): Kevin Buchin, Maike Walther.
In Book: Wolfgang Engel, Rendering Techniques, pp. 340--347, Wordware Publishing, Vol. ShaderX2 - Shader Tips and Tricks, September, 2003.
[BibTeX]

Abstract:
Hatching is a common technique used in Non-Photorealistic Rendering (NPR). For hatching, series of strokes are combined into textures. These compositions of strokes can convey the surface form through stroke orientation, the surface material through stroke arrangement and style, and the effect of light on the surface through stroke density. Up until now an important issue of real-time hatching techniques has been how to employ the limited programmability of the graphics hardware currently available. Pixel programmability has now reached a state where we can shift the focus to adding more flexibility to the hatching scheme and combining hatching with other techniques. We present a hatching scheme and some extensions to it, namely interactively changing the stroke style, and hatching with specular highlights. As an application, we show how we integrate hand drawings into a scene taking into account the effect of lighting. Finally, we show how to choose a color for each stroke depending on the background color, which can be used for a pointllistic style.