Merge Together Irradiance Cache Files

[kubabuk]

Hi,

There is one thing which confuses me all the time, I definitely misunderstand something, or I have just spent to much time with Vray settings. Could someone explain me please what is irradiance caching for? To me that is some kind of IPR for light settings and this option is completely useless for rendering animations and eliminating flickers.

What I wanted to do is to gather light samples every couple of frames and save everything in one irradiance file. Next reuse it during "everyframe" render. The light settings will be fixed then and flickers should disappear. But at the moment I came up to a problem that I can't add to existing irradiance cache file newly generated samples. I could create a new file for each frame, which is not bad, but how can I merge them together?

thanks a lot for any help

k.

[MADjestic]

as far as I understand the idea behind caching - it allows you reuse the lighting setup - you render your GI setup once, write the GI cache and then read it back, thus speeding up the rendering, You can play with different shaders set up and get faster GI rendering all togather (this way it is similar to RPI). Obviosly you need a separate cache file for every frame (if your camera/objects are animated). What's the purpose of merging cache files?

hope that helps.

[kubabuk]

Merging several cache files together gives you a possibilty to reuse that file for each frame and to get rid of annoying flickering in your animation. What I thought about is to bake each frame with lowquality (resonable time) irradiance settings and merge all of the cache files together. This way you will get light representation of your scene. Since you are useing the same file for each frame (even low-sampled) you don't need to bother about any flickering problems. The drawback of that method is that it works only for fly-throughs, when a camera is the only animated object in your scene.

In Vray (3dsmax) this technique speeds up animation significantly since you can bake cache files, let say, every 10 frames to cover only "new" areas in your animation.

I think this method is doable to replicate in Houdini but I right now I have some problems. I am able to convert irradiance files to pointclouds and merge them but have difficulties bringing them back to cahce file (using i3dconvert). I would be very gratefull if somebody could point me any place where I could get some help...

thanks

kuba

[MADjestic]

Hmm...maybe I am misunderstanding the process, but won’t caching a single irradiance cache file of sufficient quality and then setting the caching to Read Only suffice your needs? Isn’t caching 1 high quality GI is the same as, as you put it, merging several low-quality cache files?

Btw, haven’t you tried baking your GI?

Btw – are you using GI lighting or GI shading?

Another idea - if you can get your irradiance cache into point clouds - why not just using the pointclouds data for baking your lighting/shading?

[Andz]

..Obviosly you need a separate cache file for every frame (if your camera/objects are animated). What's the purpose of merging cache files?

I think you can in vray, but only for camera animation, not object.