Light Cache Calculation under DR?

[3ddesign]

I've always used IR and QMC but am experimenting with IR using Light Cache as secondary bounce. I've read on the forum that I should be able to calculate the Light Cache using DR but can't get it to work. Any help would be appreciated.

[vlado]

The light cache calculations are not yet distributed. This means that each machine will calculate its own light cache from scratch. Usually this is not much of an issue as the light cache calculations take a small part of the final image rendering. It may be a problem if the machines used for DR are very different in speed in which case some machines may lag behind too much. In that case, you can precalculate the light cache on the fastest machine and save it to disk, so that all slaves can load it directly during the DR.

Best regards,
Vlado

[3ddesign]

Thanks Vlado. I'm curious about your statement that the Light Cache Calculation is a small part of the rendering. Maybe I'm doing something wrong but when I switch from IR/QMC to IR/Light Cache, render times skyrocket. It can take up to an hour to calculate the LC when in IR/QMC the whole render might take 5 minutes. I'm using the settings described in the tut by 3DAS, Visualization Insider, Critical VRay Settings. Thoughts?

[vlado]

It would be helpful if you can give your exact settings. From what I have experienced, at 2000-3000 subdivs it would be unusual for the light cache to take more than perhaps 10 minutes, depending of course on the exact scene, the materials and the machine doing the rendering.

A known case for significant slowdown of the light cache is when you are rendering a large resolution, using the 3dsmax frame buffer, have the Bitmap pager ON, and the "Show calc. phase" option for the light cache is ON. In this case, showing the light cache phase causes the slowdown as the 3dsmax VFB bitmap is paged constantly to and from disk. Turning off the "Show calc. phase" option solves this problem.

Best regards,
Vlado

[3ddesign]

I have show calc ON but bitmap pager OFF. I will try turning off the show calcs and see if this helps. If it doesn't, I'll post my exact settings. Thanks Vlado.

Craig

[brian451]

Thanks Vlado. I'm curious about your statement that the Light Cache Calculation is a small part of the rendering. Maybe I'm doing something wrong but when I switch from IR/QMC to IR/Light Cache, render times skyrocket. It can take up to an hour to calculate the LC when in IR/QMC the whole render might take 5 minutes. I'm using the settings described in the tut by 3DAS, Visualization Insider, Critical VRay Settings. Thoughts?

i just came across this...what settings are you talking about exactly. i can't fathom how you could go from 5 min with QMC to 1 hr with LC using any settings, especially those we talked about in that article.

[percydaman]

light cache can be finicky with regards to materials in the scene. If Im doing a low quality test render and the lightcache seems to take incredibly long? Its usually an indication I've got some material problem.

[ene.xis]

In several ocasions when dealing with very detailed scenes i have come to a point where i ve had to give up on LC cause it takes forever to calculate the secondary bounces