Slow subdivision render startups.

[daviddeacon]

Hi,

We have been suffering from some slow render startups when using subdivisions for a while now. I felt I needed to bring it up.

I have a scene with 19 mechanical arms that are all being subdivided, each arm is being subdivided with the settings on its own Vray Displacement group. Setting attached.

It takes over 2 minutes for Compiling Geometry to finish and to start rendering the first pixel. During this time, the CPU is only using one core.

If I turn off Subdivision and displacements from the render globals, I get to the first pixel in less than 8 seconds.

Is this normal? Could the Compiling Geometry phase be multi-threaded in any way, as all of the geometry is made up of separate pieces that could be processed in parallel?

Or is this not the correct method for subdividing geo?

Any help would be much appreciated.

Best Regards,
David.

[Morbid Angel]

Hi David, could you post a part of this scene for us to look at? There could be a number of reasons contributing to the slowdown. Also could you provide maya / vray build numbers you are using?

[daviddeacon]

It is part of a live project so I wouldn't be able to post it publically.

We are running Maya 2017 and VRay 3.52.02 on OSX.

[Morbid Angel]

You can email the scene to vray@chaosgroup.com, I can also take a look if you email it to silhouetteimages@gmail.com

[yolov]

You can try switching to on-thy-fly geometry generation instead of pre-tesselated. The difference is that pre-tesselated would require some preparation time, but renders faster and use more RAM, while on-the-fly should potentially start faster, but render slower and save RAM.