Mapping the Light

Lightmaps are old tech, they eat up a lot of memory, they are static, they need pre-processing, they are expensive to compute and cheap to run(except the memory cost), but they can look very natural on static geometry scenes especially if they are made with radiosity in mind. Ie, contain light diffuse interreflections between surfaces. Radiosity is a global illumination algorithm in the sense that the illumination arriving on a surface comes not just directly from the light sources, but also from other surfaces reflecting light. Radiosity calculations are viewpoint independent which increases the computations involved, but makes them useful for all viewpoints.
In the times of modern GPU's running modern lighting approaches like deferred lighting, where everything is fully dynamic and per-pixel, speaking about old tech like lightmaps is a bit odd at first sight, but if you think about the increasing mobility of the computing in general and modern hand-held devices that run on limited battery power and physical dimensions, you will see why the old stuff is gaining momentum on new devices.
Recently I went on implementing a simple lightmapper ( without radiosity ). I will outline the process and provide some code on a next post. Here are a few screenshots of how it looks like so far.