Not sure if anyone is seeing the same issue, but when I rendering a shader with a broad glossy refection using VRay Mtrl, I’m experiencing much higher render times compared to the previous version of VRay if I bump the Reflection subdivisions to 16 and 32.
I’m using the Adaptive Subdivision Image Sampler values of 2 (Max rate) and -1 (Min. Rate) which it was the same as I was using before.
why would you use adaptive subdivision?? its obsolete…
Can you post a scene for this? I can’t think of any changes that would cause this, but maybe there is something going on that I’m missing.
Best regards,
Vlado
Yes, I’m curious to know why you use Adaptive Subd sampler instead of Adaptive. I’ve never gotten it to render faster than Adaptive. Also if I remember correctly, Adaptive is much better than the Adaptive subd. sampler at rendering blurry/glossy effects such as very blurry material reflections, DOF, motion blur etc. Which your case seems to be. Detailed geometry, textures and fine detail in general are also a big problem for Adaptive Subd. AFAIK.
Thanks for the replies!
Dmitry- Not sure what you meant by Obsolete. I did a bunch of tests and each Sampler gives a different result. For me Adaptive Subdivision gives a good speed and less noise on the reflections… but maybe I’m missing some specific parameter to get less noisy reflections using Progressive and Adaptive.
Alex M- I have always used Adaptive Subdivision since it gave me a good balance between render time and less noisy renders. Please check the render tests I attached to see what I’m talking about 
But again, since I don’t have much experience with the other samplers maybe I’m missing something. :))
Vlado- Thanks for the fast reply, I will prepare the scene to save the area where I’m experiencing the issue.
Meanwhile, I attached three renders of the section I saw the slowdown. I also tested Adaptive, Progressive and Adaptive Subdivision. As you can the Adaptive SubD has the longest render time but the metal renders in a better quality.
Thanks!
That’s expected: the ASubD sampler has to take the full amount of samples per sub-pixel, so it takes, with a max of 2, potentially (4^2) 16 times more samples than the other two samplers.
This behaviour was the one saving grace of the method for rendering beauties, imho, before 3.0, to make sure one had a firm hold on the sampling happening within the scene.
MSR changed that for 3.0, and SP3 changes it further still, making it the least appealing of the four AA choices, i dare say.
It still has excellent uses for data passes and such, but for the Beauty renders, i’d give a try to progressive and adaptive first.
With twice the rendertime (halve the noise threshold for progressive or adaptive) i’d wager you’d get a much closer image to ASubD.
Ya, it makes sense! With the tests I did, progressive seems the best balance between the slower Adaptive SubD render times and the much more Noisy Adaptive. Thanks a lot for the input!!!
