IMPaSTo - A Realistic, Interactive Model for Paint
Author(s): William Baxter, Jeremy Wendt, Ming C. Lin.
Proceedings: 3rd International Symposium on Non-Photorealistic Animation and Rendering (NPAR'04), pp. 45--56, June,
2004.
[BibTeX] 
Abstract:
We present a paint model for use in interactive painting
systems that captures a wide range of styles similar to oils or
acrylics. The model includes both a numerical simulation to recreate
the physical flow of paint and an optical model to mimic the
paint appearance.
Our physical model for paint is based on a conservative advection
scheme that simulates the basic dynamics of paint, augmented
with heuristics that model the remaining key properties needed for
painting. We allow one active wet layer, and an unlimited number
of dry layers, with each layer being represented as a height-field.
We represent paintings in terms of paint pigments rather than
RGB colors, allowing us to relight paintings under any fullspectrum
illuminant. We also incorporate an interactive implementation
of the Kubelka-Munk diffuse reflectance model, and use a
novel eight-component color space for greater color accuracy.
We have integrated our paint model into a prototype painting
system, with both our physical simulation and rendering algorithms
running as fragment programs on the graphics hardware. The system
demonstrates the model’s effectiveness in rendering a variety of
painting styles from semi-transparent glazes, to scumbling, to thick
impasto.