Min. leaf size and Max. Tree depth Face/level coef?

[kriscabrera15]

I know what they do but don't quiet understand hot the work, would someone care to lend some knowledge? how do you know how much Vray is subdiving the grometry? What exactly do the values compare to as far as memory usage and all? oh and why does vray subdivide the greometry?

[vlado]

You should probably leave the min. leaf size to 0.0; it might help in some cases with rotational motion blur, but we are working on a solution for those cases too.

The face/level coefficient controls how many triangles to store in the leaf nodes of the raytracing accelerations structures. Lower values allow less triangles which makes it faster to intersect the geometry, up to a certain point. Of course this comes at the expense of more RAM. Values between 2.0 and 1.0 work best. Reducing this below 1.0 might increase memory usage without improving speed.

As to why acceleration structures are needed - without them, raytracing would be unbearably slow

Best regards,
Vlado

[joconnell]

As compared to the benefits of getting the right subdiv values, will this impact much on the render speed? Is it worth learning / looking at? Does tuning the settings only speed up the loading / preparing geometry section of the render or is that structure used all the way throughout the bucket / pixel section of the render?

[vlado]

As compared to the benefits of getting the right subdiv values, will this impact much on the render speed?

There will be differences, yes. It depends on the specific scenes.

Is it worth learning / looking at?

You could try changing the faces/level coefficient a bit and see how it affects render times and RAM usage.

Does tuning the settings only speed up the loading / preparing geometry section of the render or is that structure used all the way throughout the bucket / pixel section of the render?

The values have an affect on nearly all stages of the rendering.

Best regards,
Vlado

[joconnell]

Further down the rabbit hole so