A viscous paint model for interactive applications

We present a viscous paint model for use in an interactive painting system based on the well‐known Stokes' equations for viscous flow. Our method is, to our knowledge, the first unconditionally stable numerical method that treats viscous fluid with a free surface boundary. We have also developed a real‐time implementation of the Kubelka‐Munk reflectance model for pigment mixing, compositing and rendering entirely on graphics hardware, using programmable fragment shading capabilities. We have integrated our paint model with a prototype painting system, which demonstrates the model's effectiveness in rendering viscous paint and capturing a thick, impasto‐like style of painting. Several users have tested our prototype system and were able to start creating original art work in an intuitive manner not possible with the existing techniques in commercial systems. Copyright © 2004 John Wiley & Sons, Ltd.

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