I've noticed that the glossy reflections on DGS materials look pretty grainy. I also couldn't find any options controlling smoothnes, sampling or whatsoever.
The only way to make it smooth I found is bumping anti aliasing samples a lot... like 6 samples max. That has very good result but it takes FOREVER to render.
I usualy render at min samples 1 and max 3, and that gives me enough smoothness with all other materials and geometry in general. But it seems too low for producing a soft glossy reflection when using DGS materials
I wonder if there is some other way to achive better and most of all FASTER results
Not with dgs (use mia it interpolates, oer write your own). But read:
Anyway you can easily do a override. Now then this means you must override ALL OBJECTS in the scene. what you do is put a 0 2 override on most objects 1 3 (is ridiculously oversampled for most surfaces!) on some, and more to some. Then set the global values to -2 10 (well enough to accommodate ALL possible samplings overridden issues) (note its really really important thet you override all objects).
The bonus of above is that background renders ULTRA fast.
Now form the sound of it your have either under or over pumped the threshold attribute. Please noote that a high sampling of 6 makes absolutely NO SENSE (because that would be as if casting 4096 primary rays/pixel and that is way too much for anything other than suicide)
A second alternative wich is much better then pumping the aa values sometimes is the oversample lens shader.
10x for the answer, it got me quite a few extra ideas
However I found out that the mib_glossy_reflection is the faster way to achive better looking and faster results, I can set samples to it, and I think it is a bit more flexible when it comes to glossy than the DGS shader, plus I can use the DGS as a base material and the mib_glossy_reflection only for reflection
Since you are the man thats answering 90% of the questions arrond I would like to bring you attention to my other question here, just in case you've missed it