“LWF, Gamma, 2.2, what the hell is with all this noise in my shadows?”
Allow me to shed even MORE “light” on this subject. I’m not going to go over the whole 2.2 vs 1.0 thing yet again. There are plenty of places that can explain it in a far more scientific way than I’m capable of. What I can do is tell you what I consider the “Best Damn Gamma Practices for V-Ray in 3ds Max 2012″.
The Illusion of LWF
Autodesk would have you believe that they have it all figured out in a neat little package within your preferences (and to some extent they do). While the options in this menu are useful, they are only skin deep. They are, in fact, applying a LUT (Look Up Table) to Max entirely. To put it another way, when you follow the ordinary 2.2 workflow in 3ds Max 2012, you open up your gamma (and LUT) settings, change it from 1.0 to 2.2, you set your materials and bitmaps to 1.0 (you like to inverse it yourself, it’s way more diy), you hit apply and whalla! Max looks a little bit brighter overall and a bit washed out. It is correct though. You are working in a 2.2 space. You scratch your head inquisitively and sigh. That is because it simply applied the gamma to Max overall. Don’t be fooled, this is just how you are SEEING Max. When you hit render, it’s not thinking about things any differently than if you had not fiddled with the gamma settings at all.
Low Level Noise Be Damned!
Have you ever worked in Vray using the Max LWF and noticed an annoying noisy grain in your shadows? Annoying grain that no matter how hard you try, no amount of sampling will smooth it. You end up driving yourself mad and cranking down your thresholds till your buckets cry out for mercy. The reason that noise is there, is because it’s ALWAYS been there, it’s just that your old 1.0 gamma hid it from you. Darkened away, lurking in the shadows. Your 2.2 gamma put a spotlight on that pesky noise but because your gamma settings are only skin deep, V-Ray still cant see it. V-Ray is still happily sampling away in a 1.0 color space and is blissfully unaware of that menacing grain. We need to change that. We need to lift the blinders and let V-Ray’s superior sampler eradicate that noise!
Let V-Ray do the Heavy Lifting
First off, enter Max preferences>Gamma and LUT enable Gamma/LUT correction and change the gamma to 1.0. Why you ask? Why not disable it altogether if we are truly letting V-Ray do all the work? The answer is simple. If you disable gamma altogether, you lose the ability to change any bitmaps incoming gamma within the bitmap import dialog and THAT is a hell of a lot easier than making gamma color correction nodes and setting the inverse .4545 for every texture map in your scene. On board so far? Good. Ok, so now let’s go ahead and set up all your Bitmap input and output gamma’s to 1.0 too. Also be sure to leave affect color selectors and Affect Material Editor checked on. So really what we’ve done is castrated our gamma preferences without turning them off. Strange, I know. Bear with me.
One more step. Enter the V-Ray Color Mapping tab in your render globals , change the “Type” to Linear Multiply. Then change the Gamma to 2.2. BOOM! The earth just shook. Now V-Ray is gonna sample at 2.2 and not at 1.0! Watch out noise!
The Downside…boooo (don’t be sad, see update at bottom)
Ok so, it’s not perfect. Your unable to work in your max viewport or slate material editor in the desired 2.2 color space. That is, until Autodesk understands that LWF needs more settings (like the ability to choose what viewports, framebuffers it gets applied to). You may ask, “why not use the V-Ray framebuffer and keep Max Gamma at 2.2, just don’t enable the “srgb” button. To that I say, yes. You CAN work like that BUT, there are problems with that method. We currently render out our animations as multi-channel exr’s using Thinkbox Deadline to manage our renderfarm. We’ve found that rendering to Deadline with the V-Ray framebuffer and writing multi-channel exr’s, you often get errors. So, we tend to play it safe and stick to the Max framebuffer.
In summary…
Hey, I don’t have all the answers but I can tell you that this method works. If you have an even better LWF for V-Ray and Max, please do share it. I’m always open to suggestions.
UPDATE!!!
Thanks to Simone Nastasi for this tip! If you turn on “Don’t Affect Colors (adaption only)” in your V-Ray color mapping tab, you can turn on Max’s 2.2 Gamma and have the best of both worlds! Thanks Simone!
