subdivision?

[percydaman]

Can someone explain to me the advantage to using the rendertime subdivision over meshsmooth? Ive tried several tests and cant find a single instance where its faster then using meshsmooth, even when choosing 3 meshsmooth iterations which is frequently overkill. In fact in my tests its SEVERAL times slower. Even in a test where the vray subdivision had less then half the polys, it rendered in over double the time.

Also theres no settings to adjust amount of subdivision. Will that change?

[vlado]

You can increase the Edge length - it really does make a difference. By default VRay does far more subdivisions than a MeshSmooth.

Best regards,
Vlado

[percydaman]

ok Ill check that out. But like I said, I set meshsmooth until it created over 1 million polys and it rendered over twice as fast as the vray subdivision that generated less then 600k polys.

EDIT: okay increasing the edge length certainly makes it alot quicker.

[vlado]

But like I said, I set meshsmooth until it created over 1 million polys and it rendered over twice as fast as the vray subdivision that generated less then 600k polys.

Eh, well, one can't have everything at once VRay only generates those parts of the displaced object that are needed for rendering, in addition the subdivision level depends on how close the object is to the camera; this might or might not be important, depending on the scene. The situation is exactly the same as with displacement mapping...

Best regards,
Vlado

[percydaman]

Ive also found that vray subdivision will properly subdivide in instances when max's meshsmooth causes serious issues.

[Trapezium]

Ive also found that vray subdivision will properly subdivide in instances when max's meshsmooth causes serious issues.

Are you just talking about speed and interactivity issues?

--Jon

[egz]

VRay subdivision is view dependent. Try moving close to a mesh smoothed object and you will see polygon edges. You will never see this with VRay subdivision since it dynamically subdivides more as you get closer. Also for larger meshes the VRay subdivision will use less memory than meshsmooth.

[f97ao]

Also another enormous bonus with the Vray smoothing should be that we can use it for very large objects. Lets say 1mil base object with iterations=3, that would be a 64mil object, and totally impossible to render in max normally.
but this is possible in Vray right?
Ehm, can anyone please try this? And note the render times please. Is it possible or too slow?

/Andreas

[cpnichols]

Rendertime SubDiv is a CRITICAL part of rendering for feature films. It garantees that you will have NO faciting of an object since you can make sure that it is subdivied to the size of a pixel. Also, it will use a lot less ram then trying to brute force the result with raw polygons.

It is a critical part of why people use renderman. Originally, everything was done with nurb surfaces since it was the only way to get perfectly smooth surface. When the world started to use a lot more polygons, the world of SubDiv came along. Renderman then added the subdiv feature in the rendering engine that would subivide the surface at rendertime in the same way that it did nurb surfaces.

Combine that with the displacement map, and you have a the winning combination.

[percydaman]

good point

[honzal]

chris, I would say " a killing combination"

jan

[cpnichols]

chris, I would say " a killing combination"

jan

haha... well it is a violent world these days... winning may be a little more positive.

[Robert]

Remain the problem of Mesh Count.

If you use this option in a scene with alread 2 mil. polys and MotionBlur you will end up at an amout of polys and render time (you never really now how big) that can slow down rendering as well as crashing your scene. Just imagen you have Shadowmap lights, all lights have to scan the scene first.... guess that needs a try.

regards,

robert

[f97ao]

can you guys please try how big objects you can smooth?
Try a 500k object with smoothing, can vray handle that?
max would not be able to handle it
/Andreas

[egz]

Andreas: Just tried smoothing a 293k object and VRay had no problems doing that. However, you have to keep in mind that the smoothing adapts to what you can see, you'll get just as many polys as you need to keep the surface smooth.

Robert: The smoothing is generated the same way displacement is (micro triangles) and they only exists while they are needed as far as I know. Here's a test with shadow mapping: