In between bouts of festive over-eating I added support for blackbody emission to my fluid simulator and thought I'd describe what was involved.
Briefly, a blackbody is an idealised substance that gives off light when heated. Planck's formula describes the intensity of light per-wavelength with units W·sr-1·m-2·m-1 for a given temperature in Kelvins.
Radiance has units W·sr-1·m-2 so we need a way to convert the wavelength dependent power distribution given by Planck's formula to a radiance value in RGB that we can use in our shader / ray-tracer.
Read more →