Details with rendering multiple lights with small shadow maps or one l

[kensonuken]

I have a doubt in rendering multiple lights like 40 lights with shadow map size of 8 x 8 or using one single 256 x 256 map? which can give better details? or which one is recommended? any ideas? ( this one i want to try for fill lights.. )

[Jason]

I have a doubt in rendering multiple lights like 40 lights with shadow map size of 8 x 8 or using one single 256 x 256 map? which can give better details? or which one is recommended? any ideas? ( this one i want to try for fill lights.. )

Shadowmaps are fast to generate, generally. I'd not go below 256x256.

[ihab]

I know that shadow maps are generally faster to render than raytraced shadows but i tend to avoid them in houdini because of the fact that it's not multithreaded. When i render volumes i'd rather use raytraced shadows on a multi core machine than use shadow maps. Any decent resolution of a shadow map takes longer to render on a single core than raytracing on the whole lot of cores you got. I don't know if this is the general case with houdini or is there a workaround for this at the moment.

[Raf]

Multithreading for shadow maps is problematic for Mantra and Prman too, so you should cache them and reuse in final rendering. Sometimes is good to run simultaneously 4 or more processes(renderings) on one machine with multithread option off in renderer properties. In most cases 1 job per one core give best performance usage, but it is depend on scene and how much Ram you have in your computers - 2Gb per core is a good idea.