AO, Radiosity, Yafray ?

This is probably a stupid question, but it is a while now that I use Blender (Great program !) and I think I know when I should use internal render engine (not often), AO or Yafray (Mainly to get Caustic light and HDRI), but why should I use Radiosity, I never tried it and I don’t know if I should ? Could somebody make a quick comparison of the render engines provided with Blender ? What could Radiosity provide ?

Thanks

@ radiosity: (I’m probably not the best one to answer this, as I’ve not used blender’s internal radiosity tool,) but AFAIK, its not an actual raytrace-calculated solution. It essentially is a method which precalculates the lighting in such a way as to subsequently alter various material settings in an attempt to simulate what raytraced radiosity does, using the internal scanline engine (it was implemented before blender picked up raytracing in its internal engine.) There are tutorials linked here at elYsiun which will give you more info about it. (And as always, check the wiki manual.) However, when you use Yafray set to Full GI, you’re essentially getting raytraced radiosity calculations in your output (and maybe with Skydome, too, I dunno for sure…) See www.yafray.org for more info on that.

Thanks for your explanations, this helps me to clarify the purpose of radiosity.

The purpose of radiosity is to aid in ambient lighting of your scene by including light that bounces off of the various objects in your scene. This light, when it bounces, picks up certain characteristics of the material of the object from which it bounces (such as its color, for example.) This is why you commonly see the cornell box image, which is designed to illustrate a raytracer’s capacity to produce radiosity effects.

To my understanding, Blender’s internal engine does not use its raytrace algorithms to apply radiosity affects to the output, but relies on other methods calculated prior to rendering. Yafray, on the other hand, does perform these calculations via its raytracing algorithms. (Someone may need to correct me or clarify, here - my understanding of the technical details is somewhat lacking… :wink: )

Thank you for these helpfull information, it seems that Yafray provide the radiosity functionalities, I think I will not investigate deeper with the radiosity functions in blender for now.

I really appreciate.