PLY-derived V-Ray proxies: Crazy long light cache build/render times

[Zirnworks]

I took a modest .ply file (only 1.74 MB / 15,300 points) and converted it to a .vrmesh using the "OBJ GEO PLY to .vrmesh converter Next 4.0" console. I had been planning to scatter much denser ones in my final scenes using Multiscatter.

I brought the proxy into a V-ray scene with a Vray sun/environment map, to do a test render. However, the "building light cache" phase took about 10 mins, despite turning light cache subdivs down to 250. (The output size is only 600 x 450 px, and yet the first pass on my progressive render has been cranking for over about 20 minutes with no end in sight.)
Performance was obviously much worse with one of my denser point clouds, and it was building light cache for over 40 mins before I just stopped it.

I need to be able to render lots of point clouds per V-ray scene, and it seems impossible at this rate. Am I doing something wrong? What is the ideal workflow?

Thanks.


Note: I AM able to render point clouds if I convert them to .rcp files and bring them in as a point cloud object in Max. However, it receives no light information when rendered in V-ray. I'd really like to get both working if possible. (Attachment to illustrate this below.)

[vlado]

There are some parameters for ply2vrmesh that might need adjustments, but I'm not quite sure what would yield best results. Do you think you can get me an example .ply file to vlado@chaosgroup.com so that I can play with it?

Best regards,
Vlado

[Zirnworks]

Thanks, Vlado! I sent it off to you. Indeed I didn't apply any special parameters when using ply2vrmesh.

[vlado]

So this is because the ply file does not contain information about the size of the particles and ply2vrmesh by default sets that size to 1.0. However your particle cloud is tiny and this size for the particles is enormous. Use the -particleWidthMultiplier for ply2vrmesh to specify the particle size, for example:

ply2vrmesh MandelbulbPower6-64.ply -particleWidthMultiplier 0.001

or this:

ply2vrmesh \MandelbulbPower6-128.ply -particleWidthMultiplier 0.0005

When you do that, render times will be normal again (see attachment).

Unfortunately there is no way to control the particle size inside 3ds Max for .vrmesh files; if you want to change it, you will need to reconvert using ply2vrmesh again. But on the other hand, this allows ply2vrmesh to pre-process the particles for more efficient rendering so that you can render millions of those.

Best regards,
Vlado

[Zirnworks]

This indeed solved the issue! Many thanks for taking a look.

Looks as though there isn't a command for changing object size in the converter. I've turned to doing that in CloudCompare instead. Still getting a handle on this file type.