Vray rendertime subdivision

[doctorbeat]

Hi there,
can anyone please explain why the vray Max subdivisions parameter only works in increments of power+1?
as in 1, 2, 3, 5, 9, 17, 33, 65 and so on... all the numbers in between don't increase the subdivisions at rendertime. and why not do it with a sequence of numbers, like 1,2,3,4,5,6...

Thanks

[yolov]

Is this with view dependent subdivision or view independent? In any case there's a parameter called "edge length" that defines the maximum length of a subtriangle (i.e. how small or big is each subsequently subdivided piece of a polygon).
High values will prevent the mesh to be further subdivided. Think of it as a threshold criterion. So for example if you're at a high value for the edge length, you'll only get more subdivisions up to a certain amount of max subdivs, because the cut-off has been already reached by the edge length. It will prevent vray eating up all your RAM in case you enter a value of, say 1000. The edge length will be in pixels when it's view dependent and in world units when view independent.
Does this help?

[doctorbeat]

Thanks for the reply, i was testing with view dependent turned off, and an edge length of 0.5, which means that the mesh will always be subdivided the amount of times specified, regardless of size and how close it is to the camera.
My question is why it subdivides predictably at level 1,2,3, then 4 doesnt subdivide any further, then 5 adds another level of subdivision, then up until 9 it stays the same,.... the subdivision levels that actually work are 1,2,3,5,9,17,33,65,... try it with a vray edgetex and see what i mean. i can work with this, its just not very intuitive, and I think linear values would be easier to understand, as each number would subdivide the mesh further, like zbrush

[vlado]

The value specifies the desired subdivisions along the edges of polygons; they are not subdivision levels. The reason is that originally V-Ray could tessellate at rates that were not powers of two; this saved memory but had some issues and we had to drop it eventually; however old scenes still needed to render as before. Also, having the linear edge length guards a little bit against entering insane values.

Best regards,
Vlado