vrMesh questions

[eldiablo]

1. when you have huge data sets what is the best path to follow, larger bounding boxes or more instances.
2. does creating instances in Maya correctly instance in vray?
3. can you instance just the geo data and set different shaders.
4. Is there any thought of splitting a vrMesh into multiple components. Geo, UV, shading, etc. Essentially a vrMesh is an assembly of many parts.

thanks in advance....eldiablo

[vlado]

1. when you have huge data sets what is the best path to follow, larger bounding boxes or more instances.

Instances conserve more memory.

2. does creating instances in Maya correctly instance in vray?

Yes.

3. can you instance just the geo data and set different shaders.

Yes.

4. Is there any thought of splitting a vrMesh into multiple components. Geo, UV, shading, etc. Essentially a vrMesh is an assembly of many parts.

The .vrmesh file stores only geometric information + uv channels. Shading is specified separately in the Maya scene.

Best regards,
Vlado

[eldiablo]

got it. But here is the problem I am having. I have a parking lot with 8500 cars in it. I wrote out 10 different vrMeshes of individual cars and instanced them randomly 8500 times. Each vrMeash is instanced and has a unique material input for texture randomizing. When I go to render the scene with only the instances and a dome light it takes forever to write out and forever to render. So I tried another approach by doing vrMesh splits of the scene by writing them out to 4 sperate vrMeshes with one shader input that has multiple input slots for randomizing materials. This approach was more successful, about 1/10th the time. Funny thing is the bounds of the latter is enormous compared to the tiny ones instanced everywhere. Also the file size for each split is over several gigs each compared to the individual vrMeshes instanced files which are around 600k each. Is there something I am doing wrong here?

As to your response to question 4, I would love to have the UV's seperate from the geo in the vrMesh. It would give lots of flexability for parrallel development, pref space, shot specific UV changes.

thanks...el diablo

[vlado]

Whenever you are dealing with proxy objects (and things like displacement, hair, fur etc) you need to increase the dynamic memory limit; the default size of 400 MB is way too low.

About the UVs, it can't be done unfortunately. The .vrmesh files are in a ready-to-render format, where all geometry info is already baked in. You can, however, play with the offsets, tiling, scale etc of the UV placement nodes that are used in the textures.

Best regards,
Vlado

[eldiablo]

Thanks for the quick reply. The preset we are using for dynamic memory is 24000. Is there a possibility that the more instances problem I am having is related to network speed?

[djx]

I've been experimenting with this also. I've been creating vrmeshes of trees, cars, grass and animated people. I found that maya seems to slow down considerably the more transform nodes you have. I try to keep it under 500 (1000 maximum). So I would make my vrmeshes according to that. For your example of 8500 cars I would have tried maybe 25 cars per vrmesh, resulting in 340 instances.
I'm also surprised that your file sizes were so large. Take my grass for example. I created vrmeshes from almost 1 million quads and I think the file size was only about 30 MB (I'm going from memory, so this is not exact). I was able to place 500 instances of these in a scene which rendered at about 6 mins per frame (dome light and 3 rect lights, no GI) (dynamic ram = 8000).

When I tried to created vrmeshes with considerably more polys, maya started having problems, but I think this was due to the graphics card limitations.

I had similar success with animated characters, except that for those the file size IS very big. For farm renders the size of these files had a significant impact on render times.