Area Shadow Subdivs - How to Optimize

[rs3d]

I'm currently using Area Shadows for very fine objects creating
spread shadows. When I want to see no shadow noise I have to
set Subdivs around 64 or more, but this becomes really really slow.

Is there a way to optimize Area Shadows apart from that? I'm
not using GI or anything, but rendertime explodes...

Best, Robert

[joconnell]

It's a tough one in a lot of ways - there doesn't seem to be a single rule as to how to get the best render times with vrays sampling. You've got the option of three things with your area shadows - up the area light samples, use the dmc sampler and noise threshold or try your anti aliasing. All three will in theory work in the end but it's hard to say which will do the best job without running a few tests. If the majority of your frame is clean aside from a small portion with the area shadow in it, it's probably best to up the samples for the light causing the problems. If your area shadow is taking up a large portion of the final render then you can start looking at the other two. Try doing a render with your clean settings on the area shadow, then try another render where you drop the shadow samples back to 8 and put the anti aliasing up quite a bit - as in something like 1, 32 with adaptive qmc anti aliasing. Then try another render with aa at 1,4 and your shadows still at 8, then try using the dmc sampler to up the max subdivs and lower the noise threshold. Note down the render times for each and see which one works best for you in this case.

[Subburb]

+ 1 !

my 2 cents : you can try aa 2-4 instead of 1-4. Impact is low on rendertimes but can help to avoid dark zones with only 1 subdiv in your pic. It can help, or not, depends of the noise thr.

[rs3d]

Thanks guys, I'm including a reduced sample scene that shows
the problem. On my PC it takes 1:04 min with Adaptive AA (-1/2)
to render, which is quite much for such a simple setup in my
opinion.

DMC (1/4, changed Noise Threshold 0.05) looks a bit worse and
takes the same time 1:05 min. DMC (2/4) is much slower 3:36 min.

Maybe you can comment on the scene directly. Thanks in advance,
Rob