Humanity’s taming of fire was supposedly one of the defining moments in early human history. Ever since, people have retained their fascination with fire. People may not regularly use fire nowadays for heat or light but they still love it anyway. Why else would there be so much research on modeling it? Well, some models of fire are actually supposed to replicate its functions for firefighting purposes, but a lot of others want to make virtual fire that most closely replicates the real thing visually. And what reason could one have for that, other than ‘fire looks cool’? It’s the reason for steps 12 and 13 of our most recent project.

Speaking of this project, we render the fire as a particle cloud, and the particles flow according to a field of velocity vectors. This is capable of creating very accurate looking and dynamic virtual fire, but needs lengthy computation and uses large amounts of data. This is of course what scientific computing is all about.

Using particles to simulate fire was first done in 1983, but of the rendering of fire has come a long way since then, and the most realistic flames are far more complicated than our own. People can make their fire simulations change color according to the chemical composition of its fuel. They study the radioactivity and light cast by the flames, and use physics to determine the motion of the particles. They even model the temperature and density.
This rendering uses the spectroscopy of sodium.
This flame uses methane as a fuel
Here the fire is used as illumination and reflects on shiny surfaces.

Fairly recent research uses gaseous blobs instead of particles to model fire. Their densities are affected by wind over time (hello ODE’s). A very realistic looking model from 2002 uses three distinct fields: a blue flame core, blackbody radiation, and smoke/soot. The core is a thin film adjacent to the implicit surface where burning occurs. Blackbody radiation produces the yellow color, but changes with temperature (yellow to red to black like our colormaps, but probably fancier). The smoke and soot appear as the blackbody radiation dies down.

The information in this blog post relates to the techniques most similar to our project, but there are many other ways to render fire. Different techniques can render fire in real time, or model the behavior well. There’s even research on ways to render fire both photo-realistically and in real time. Many models don’t use fields, but to find more information about them you’ll have to look at the links below.

http://www.cs.umd.edu/~mount/Indep/Yulia/fire.html#Physical

http://www-graphics.stanford.edu/courses/cs348b-competition/cs348b-04/fire/index.html

http://www.cs.utah.edu/~vpegorar/research/2006_EGWNP/

http://research.csc.ncsu.edu/stereographics/ei07.pdf