irradience mapping vs final gathering

[Morbid Angel]

Well this morning while being hung over...i thought of final gathering method and well, I was trying to figure out what it is and came to conclusion that its something not many people understand. I mean I know how it works and what it does but as a type of gi tracing I couldnt compare it to any known types i.e. quasi.
So I thoguth that its most closest to irradience mapping. But Im wondering if anyone can explain the difference between the two?

[cpnichols]

Here you go:

http://www.cgtalk.com/showthread.php?t=238889

[Morbid Angel]

thanks
imho final gather is old and obsolete...I did not see a good final gather gi trace like quasi...

[cpnichols]

I would not say that. MentalRay has some pretty amazing results with Final Gather, and it has gotten zippier over the years. But basically, they are very similar in method and concept.

[vlado]

They are both irradiance caching methods based on point clouds. From then on, you can make infinite variations of the same method, which differ in the way the points are calculated, distributed and interpolated. finalRender also uses a method based on irradiance caching with point clouds. Brazil uses irradiance caching too, but in its case, the cache is linked to the image raster, in the same way as the 3dsmax Light tracer.

The first irradiance caching method was proposed by Greg Ward and is currently used in the Radiance package.

On the whole, irradiance caching is one of the most widely used techiques for accelerating GI calculations, supported by nearly all modern renderers - although they may call it by different names.

Best regars,
Vlado

[Morbid Angel]

I see...However I dont understand how brazil uses irradience if its only based on quasi monte carlo?

[ngrava]

Quasi-Monti Carlo is just referring the the way the sample pattern is generated. With Classic Monti Carlo the values are picked at random. With Quasi, a mathematical quasi random sequence is used instead. This has many advantages in that it is more controllable and will not sample points that have already been sampled because it is actually a pattern that eventually fills itself in.

-=GB=-

[timmatron]

Less thinking & more drinking! :P