Keith Johnson

Nice! Thanks for the rendering tips guys. I have no doubt I can get these render times lower. With time I'll have a better feel for it.

There was a question on the vimeo comment board about render settings, so I thought I'd elaborate a bit here.

Renderer was PBR, and after tweaking render parameters in a bracketing/wedge fashion, I found the two most important variables in achieving quality versus speed were the pixel samples and noise level. Those are the main numbers I tweaked to flip between a low-quality/fast preview render and the hi-quality final render. The other variable that's a bit hard to quantify, was that I had to increase the shading quality on a few key pieces of geometry (I did this on a per object basis - bumping it up from the default 1 to something around 3-4). As I state in the video, this was mainly to fix what looked like an odd dicing error on large n-gons that were utilizing gridded bump maps to simulate panel seams.

As for the other settings - I found a law of diminishing returns kick-in with the Max Ray samples. It appeared anything over a value of 6 did little to the render. Also, on the limits tab, it was important to keep the Reflect, Refract, and Diffuse numbers as low as possible. Any values above 2,2,and 1 respectively, achieved only a minor bump in quality, but a huge increase in render times. So that's basically the unscientific way I arrived at my render settings! Screenshots for both the low-quality and final-quality settings are attached.

I found with low-quality settings, interactively tweaking the shading and lighting was pretty good…at least good enough for me to move forward without getting frustrated. As I state in the video. With the final quality setting, rendering at 2000 x 2000, the rendertimes were generally around 8 hours. This is on a 2nd generation i7 machine, capable of turboboost above 3 GHz with 12 gb ram. One thing I did notice is that my machine was very rapidly using up ALL of the ram with no headroom, so I imagine it would be a good thing to upgrade that. Thankfully, Mantra does not just crash on you when you hit the ram ceiling, like V-Ray used to be notorious for. Still, 8 hours for a 2000x2000 render seems a little steep. And it still may have been too noisy for animation. This didn't bother me for a small test project, but it could be an issue later if I do full animation work for a production.

Really though, the speed was my only gripe. Mantra was incredibly stable, reliable, and predictable. I don't think I had a single crash or freeze while working with the interactive render, and the dicing error I stated above was the only unexpected surprise that required troubleshooting.

Thanks guys. Having fun with Houdini.

Werner - thanks! Glad you find the videos useful.