Large scene memory management

[Joelaff]

Any pointers on memory management for large scenes?

I am doing a lot...

All textures are tiled 8bit .tx files or tiled .exrs when float is required. All VRayHDRI nodes, not bitmaps.

High poly models are vRay proxies whenever possible.

I am using embree for motion blur (does that ignore the BSP settings completely?) I tried traditional motion blur but got higher memory usage (possibly was too aggressive with the face level coefficient). I have enabled conserve memory for embree.

My objects tend to animate and then go to visibility 0. The shot has lots of pieces transforming into other things. Flipping around and turning on an off.

Is animating the visibility (which typically has a stepped curve in my case) the most efficient method for this? Will geometry that is visibility 0 still use memory and slow things down? (Seem like it may be). Is there a better method? Delete mesh modifier? If a vRay proxy has a visibilty of 0 is it ever loaded? Hopefully not... .?

About 8 to 10 of our render nodes still have only 12GB of ram, and they are thrashing on this. Trying to get their speed back be reducing the memory footprint.

My understanding is that if I have filter maps for GI turned on then the GI will only use the lower res MIP maps as needed from the tiled images... Right? I have a custom GI filtering strength of 2.2 as it seems to reduce noise in the interior. Does this custom strength mean the maps get loaded twice?

The light cache eats up a lot of memory. Any way to help with that other than fewer samples? I have to use camera path or I get flicker.

Any thoughts, tips?

Thanks.

[Joelaff]

BTW, what is "compiling geometry"?? Is that the generation of an embree ray cast accelerator? Or is that somehow collapsing geometry or what? I have some objects where that takes a while, and wondered if there was anything I could do to reduce it.

Thanks.

[Joelaff]

Seems like compiling geometry is displacement. Odd that some objects without displacement get this (and show as displaced in the verbose logs).

If one slot of a multi sub object has displacement does any object with that multi sub object applied get displacement, even if that object has no polygons with the ID of the displaced material? Hmm, maybe this is an issue for me.

[Joelaff]

Wow...

After doing the displacement the right way, with a VRayDisplacementMod rather than the lazy way of using the displacement slot Ina VRayMtl I am seeing a faster render and less memory usage. I had a monolithic multi sub object material on a bunch of objects (imported geometry from other software). This had just one out of forty mat IDs with dislplacement. This was then applying displacement (or at least seemed to tesselating given the speed and memory usage) to every object with this multi sub obj applied, even though I only needed the displacement on a single object.

Granted, I could have just moved that one material out of the multi sub object and still used VRayMtl's displacement channel. I prefer the modifier for more control though.

[Dave_Wortley]

Are you aware of the default displacement rollout in the render settings for displacement settings that are not applied using the Vray Mod?

[Joelaff]

Dave, yes, thanks. I use it all the time. It is great if you want to globally set the displacement settings.

The VRayDisplacementMod just offers some additional features and a per object displacement control.

Using the displacement in VRayMtl does have the added advantage of being able to easily use a VRayOverrideMtl if you need to.

To clarify my issue was the multi sub object with one channel having displacement. I certainly could have used the VRayMtl displacement.