Rendering an animation with moving objects II

[andy_butler_7]

Hi all.

Just a quick question I hope someone can enlighten me on!

3ds Max 2010 64bit
Vray 1.5 SP5

We are rendering using the following guidelines http://www.spot3d.com/vray/help/150S...ials_anim2.htm as we have moving cameras and moving objects in our scene. It works great, but i have just one question regarding the setup which i can't get my head around.

The animation pre pass uses IM and LC for the GI, which is fine.

The second pass only uses the saved IM and it has secondary bounces turned off. This is where i don't fully understand the reasoning for generating the LC in the first pass, if the second pass isn't using it.

Does Vray somehow embed the part of the LC it needs in to the IM for each frame when it renders? Is the second pass using the LC in any way? Lastly, why in the prepass are we generating LC if we're not recalling it in the second render pass?

It does work really well though, I'd just like to know the reasoning behind turning off secondary bounces.

I hope someone can shed some light on this, if you excuse the pun!

Cheers.

Andy.

[super gnu]

yes. after calculation the info from the lc is stored in the irradiance map.. basically the imap contains all the lighting info for the visible pixels, but it uses the info from the lightcache to work out that lighting solution. this is why you can turn off sec. bounces after calc phase. this also saves a bit of ram i believe, since it doesnt bother loading the lc info again.

[andy_butler_7]

Ok, fair enough!

How come you have to specify an output for the LC then? It seems odd!

Does this only apply to this rendering method in particular? We use IM and LC for stills, sending a separate GI pass that saves IM and LC files. Then a second render pass that are set to "from file" for IM and LC. Can we tell this second pass to have no secondary bounces too?

I'm intrigued!

Cheers.

[super gnu]

yes you can indeed... there is no reason in this case to save the lightcache. you have the option to, so you can use it later if you needed to (for instance if you wanted to recalculate the imap, without recalculating the LC.., and also, i believe, if you are using "use lightcache for glossy rays" you need the lightcache loaded.