I am having a real tough time with something that I feel shouldn't be so difficult to address, so apologies in advance if any of the frustration and/or helplessness I feel at the moment comes across in my question, but with a deadline creeping and nothing I am doing having a tangible impact, I am starting to feel it.
Ok, so here it is. I am doing a product visualization project. The product in question has buttons which are a sort of smoky chrome. The overall color is dark, but the reflections are pretty sharp (I have an actual demo unit so that I can dial in the look of the materials). Up until the end of last week, I was rendering only close up stills, and everything was looking good. I then rendered a rather lo-res 360 degree spin around animation, and again... things looked good. Then, on Friday, I rendered out a mid-res animation (1285x796). After 14.5 hours, when the render was done, I took the exr sequence in AE to evaluate, and it was then that I saw for the first time, the specular highlights on the button bevels was chattering like crazy as the product slowly rotated toward the camera. Ugh.
So I looked into it, took a dive into my AOVs and saw that they all looked great until I got to direct specular and that is where I saw the sort of jagged white line along the button bevel. Ok, cool... I now know where the problem is, and after digging through the documentation it seemed like there would be 2 ways to address it. First, increase the specular roughness (I had it at .1). I increased the value gradually until I got to .4 at which point is seemed like it might be better, but the material now had a more blurry reflection than its real life counterpart - and to be honest it seemed like there might still be a little of that jaggedness along the bevel edge, but it was being hidden more, and I am not sure that the chattering effect would have gone away in an animation.
The second thing I saw to adjust were light samples. Now, I have 8 lights in my scene, one spot, and 7 quad lights housed in soft boxes. 3 of these are fixed, ambient lights, and the others are positioned to the product some dramatic bits of light and dark areas. All of the lights were at 3 samples, so I gradually adjusted up, waiting longer for each render as I did, and no matter how high I set those values (at one point I was all the way up to a ridiculous 12 samples), the render showed no perceivable change.
So, now I don't know what to do... this is my first project with Arnold, so maybe (hopefully actually) I am missing something obvious, and I really hope there is someone here who can shed some light on what I might be doing wrong.
My current settings settings (initial animation settings in parenthesis):
- Camera AA - 7 (6)
- Diffuse - 5 (4)
- Specular - 7 (4)
- Transmission, SSS, Vol indirect all at default 2.
Here are a couple of screenshots (can't show the whole product as it has not been released yet)
Notice the area around the edges of the rectangular buttons, especially the long one furthest down in the frame: This is from the initial render, but as stated no amount of sample tweaking made any noticeable difference to the look (I took shots after ever change to observe and compare differences, and was dismayed to see none)
Now here is a shot from my boosting spec roughness to .4:
It does seem to diminish the severity of the issue, but I honestly think its just due to there being less contrast between the Botton's top surface and the bevel. It could be in my head, but I feel like I still see some of that jaggedness which would lead to chatter when animated.
And just to show there isn't anything particularly odd about the shape, here is a close up of the Gouraud shaded button geo:
Thanks so much in advance for any suggestions.