Paint program renders ink physics

Making good art with digital versions of traditional media requires talent, inspiration and physics -- or more precisely, accurate simulations of physics.

Although it is easy to simulate various processes on a computer, the physics of ink flowing into an absorbent surface like paper are quite complicated.

Researchers from the Hong Kong University of Science and Technology have developed a brush-and-ink-style paint program, dubbed Moxi, that uses a model of pigment particles in water flowing into paper.

The software models the gritty details of paper absorbing water and pigment moving through through water, including the way pigment concentrates at ink boundaries as water evaporates from drying ink. The technique promises to make computer paint programs with more realistic and could also be used in computer animation packages, according to the researchers.

The simulation is based on mathematics -- the lattice Boltzmann equation -- that physicists use to model the complex behaviors of fluids. The model simulates more complex effects than previous work, and is also fast enough to deliver ink dispersion simulations in real-time on a reasonably large canvas, according to the researchers.

The researchers' prototype runs on a personal computer with a pressure-sensitive pen tablet. To turn the prototype into a commercial-grade software package, the researchers have to make it more user-friendly and add abilities like rendering high-resolution outputs from recorded painting sessions, according to the researchers.

The technique could be used practically in one or two years, according to the researchers. The researchers are scheduled to present the prototype at the Association of Computing Machinery (ACM) Special Interest Group Graphics (Siggraph) conference in Los Angeles July 31 to August 4, 2005. (MoXi: Real-Time Ink Dispersion in Absorbent Paper).