I’m not able to reproduce the problem with the attached file. Are you using CPU or GPU?
The light path thing on the sun lamp is rather odd, but I think it should be ok? I would consider disabling MIS with the sky texture, or at least lowering the sample count to 1-2.
Again, I can’t reproduce the issue and I’ve never seen it in my own scenes.
I hardly ever use regular PT for anything. BPT is much more efficient on most scenes once you learn how to use it. FYI, Arnold’s only render mode is essentially BPT, there is no regular PT mode like Cycles has. I have never seen this widely complained about, and I wouldn’t use it if they added it. I recommend using the “square samples” option with branched path for simplicity’s sake.
BTW, I wouldn’t use 14 for the AA sample level unless you have a specific reason to do so. (ie, depth of field noise, GPU timing out, etc). Try starting with AA=4, and adjust the subsample levels from there. If you have a lot of sample objects, or motion blur, or DOF, you might need to raise AA samples to something like 6-8, or maybe higher. Also, if you are using GPU, excessive subsample levels can cause the some OS to kill the driver/app for taking too long to respond, so lowering them and increasing AA to compensate can workaround that.
I am using GPU (GTX 580-3gb). Using the CPU the problem goes away!
Perhaps this will be a bug? I hope there is someone who tries some other gpu maybe newer than my!
what is a node copied from somewhere but I do not remember where
Using the CPU the problem goes away!
ok, tnx
I know these tutorials but I have not been at all useful
thanks J_the_Ninja for all the other tips.
I will take even those
Yep, that was indeed a bug in the light falloff node in combination with a sunlamp. It should be fixed in the next nightly builds (and 2.77).
Thanks for mentioning and providing the file!