To Örebro University

This report describes the development and prototype implementation of

a method for baking and compression of lightmaps, in an environment

with dynamic lights. The method described can achieve more than 95 %

compression eciency, and can be easily tuned with only two parameters.

Even without specic tuning, the prototype consistently achieves signalto-

noise ratios above 30 dB, reaching 60 dB in some scenes.

Compression is achieved in four steps, rst by using image segmentation

and function approximation to reduce the data-size and then using a

predictive quantizer approach based on the PNG-lters together with an

open-source compression algorithm. Both compression and decompression

can be adapted for asynchronous and multi-threaded execution.

Denna report beskriver utvecklingen av en metod for bakning och

komprimering av dynamiska ljuskartor, i renderingar med dynamiska

ljuskallor. Metoden uppnar mer an 95 % storleksreduktion, och kan

enkelt anpassas for olika ljuskartor med tva variabler. Aven utan speci-

ka anpassningar uppnas en signal-to-noise niva over 30 dB, och narmare

60 dB i vissa scener.

Komprimering sker i fyra steg, forst genom bildsegmentering och linjar

funktionsapproximation, foljt av predictive quantization och en vanlig

komprimeringsalgorithm. Bade komprimering och dekomprimering kan

anpassas for asynkron och ertradig exekvering.