Adaptive Subdivision

[broozee]

Can anyone explain the reason behind a negative min rate setting when using Adaptice Subdivisions?

BTW - Crashed with a setting of: Min Rate = -3 and Max Rate = 8.

Thanks,
Bill

[vlado]

Adaptive Subdivision

If both rates are at 0, V-Ray will compute the image at the corners of each pixel. If the min rate is -1, but max rate is 2, for example, V-Ray will initially start with computing the image every 2 pixels in each direction, and then increase that to 4 samples per pixel in each dimension (which equals at most 4x4=16 samples per pixel), etc. Values of -3/8 mean that V-Ray will start with a sample at every 8(=2^3) pixels, and proceed to 256(=2^8 ) samples per pixel in each dimension (this means 256x256=65536 samples per pixel!). V-Ray needs to build a filter table for reconstructing the final image from the samples, and with these settings, the table does not fit into memory.

If you really must use this many samples for the image, it would be best to use the Adaptive QMC image sampler.

Best regards,
Vlado

[Micha_cg]

Adaptive Subdivision

Bill, don't forget the fine online help with tutorials.

http://www.spot3d.com/vray/help/VRay...vancedimap.htm

[broozee]

Adaptive Subdivision

Vlado - Thanks for the information. You explained it well.

Micha - My question came from the turorials of the link you posted.

It was late last night for me when this question came up so the information probably wasn't soaking in very well. It makes perfect sense now that I read it today.

When doing my tests, I was thinking that I was starting with the min rate and finishing with the max rate. It's actually the other way around.

I wonder if the UI should change the order of these two parameters? Max rate then min rate?

Micha - the tutorial at Spot.3D is really informative! Only problem is you have to disect between 3DS Max features and what VFR has to offer. That's no big deal though.

Cheers,
Bill