So is there a sweet spot of 50?? Maybe that is why it is set as the default number?
Sorry, maybe some of you know this already, but I’m glad I did the test because I will end up saving myself a lot of render time in the future by not lowering subdivisions.
The subdivisions only come into effect when you are using Glossy Reflections (then you will definitely see a difference) the difference in time must of been due to other factors.
Perhaps a good secondary test would be two (or more) glossy objects reflecting eachother, the subs do have a large effect I’m not sure why it is not showing in your test scene.
Things also depend on your AA settings. Lower subdivs mean VRay will have to do more AA in noisy areas, which may explain the longer rendering times with lower subdivs.
Yea, I was starting to think about that. So the more noise that is produced from low Subdiv settings may mean longer times to do AA. Interesting.
I was trying my test some more with more objects of the same material. On one test the difference between 3 and 50 was only 1 second in favor of 3.
So I guess generally speaking, lower subdivisions do mean better times. But at the same time, I think there would be a sweet spot for every condition. yikes! guess its all about trial & error.
Ok, this is the scene I’ve been testing. All objects have the same material applied.
I tried same rendering at different subdivision levels and found that for this particular scene, 10 subdivisions gave me the best time. Here are all of my results. The first number is the amount of subdivisions, the second number is the render time.
So, I’m sure each scene, material & reflections are completely different, but I think its still good to keep in mind that there is a point where lower subdivisions could actually cost you time.
If yes, you have to do some more tests with simple two level and fixed rate. Many people don’t understand that adaptive AA works good in Scenes with large uniform coloured surfaces but fails with scenes where a lot of per pixel effects are involved. (like your non interpolated glossy reflections/refractions) Adaptive AA tries to smooth out the per pixel mess (contrast) but fails cause the maximum number of samples is limited in the material. The result are loooong rendering times. (sometimes they’re even longer as if you’d use a higher subdivs setting for your glossy effects in your Material)
This is the same thing when you have many small objects in your scene resulting in heavy contrast differences at a small scale. Use simple two level then. (or even fixed rate!)
Thanks for the advice. I’ve usually used the adaptive AA just figuring it was typically the fastest. I’ll do some more tests on 2 level and fixed rate.
