Right time to update this! With using this at Squint Opera for the past 2 years on multiple stills and films we have a good, reliable and high quality solution. Also some really useful comments below which have changed our thinking on this, so bear in mind when reading through these that many of these changes have been included now below.
I have collected the settings below without much explanation as there are plenty of explanations on the web and it’ll take me days to explain it all. The purpose of this is to get you up to speed quickly with settings we’ve found work well.
Bear in mind your renders may appear less contrasty than usual due to the more efficient spread of light within the scene. Don’t worry about this as it will give you increased flexibility in post-production (Photoshop, Fusion, Shake, After Effects etc) with adjustment with S curves or contrast adjustment.
We’ve all done a variety of hacks to get around this non-linear workflow over the years including changing exposure curves to reduce contrast, change lights to inverse falloffs instead of inverse square, adjust attenuations, you name it we’ve done it. Just trust me, in the end you’ll love it!
You’ll also find you have to tweak a lot of your materials as these will also be previously “hacked” to get them to work. You’ll find your materials will be bright at first and super pumped in terms of specular and reflection in order to boost the light bounce you didn’t have. This is just a gradual process of adjusting this into more “realistic” realms.
SETUP OF LINEAR WORK FLOW
Firstly calibrate your screen with Gamma 2.2 and 6500K.
In 3DSmax click on Customize> Preferences and click on the Gamma and LUT tab. Change the following to 2.2:
Remember the input is for bitmaps you bring in, and these are generally taken on a digi camera with sRGB, which the same as 2.2. People have mentioned treating black and white height maps differently, but most of the time you edit them in Photoshop in a 2.2 gamma space, so these can be brought in exactly the same.
Then under render scene dialog under the vray tab>colour mapping change the following:
This combo of 2.2 gamma and ticking “don’t affect colors” means the calculations happen in linear space, and are the same as what is outputted. Affect background is optional depending on how you use it. You will NOT be able to change the multiplier and burn value now; this will only affect calculations, NOT the final image. So leave them at 1.0 always and use post processing either through VRay or post to adjust the contrast.
Note: If you are having problems with anti-aliasing on blown out pixels (shows as white squares on render) try ticking “sub-pixel mapping”. If this doesn’t fix it “clamp output” will but you will lose the range of your 32bit EXR file above pure white and will not have any information to pull it back.
This problem is usually due to materials being over-reflective, i.e. set to white, with highlight glossiness set too close to 1. This causes a massive amount of light to be directed through those pixels and VRay can’t handle anti-aliasing it, therefore it shows as a white square.
LINEAR PREVIEW AND EXR OUTPUT
You must then use the built in vray frame buffer rather than the standard render window to view the results otherwise you will not see the product of using linear work flow. You MUST also tick the little sRGB button at the bottom of the buffer window.
Again go to the render scenes dialog box and open the frame buffer tab. Tick save separate render channels and save RGB, then change the file type to EXR. (You can select a full float EXR (32 bit) or half float (16 bit). Bear in mind Photoshop only allows use of half it’s tools in 32 bit, so 16 bit is sometimes better. Other programs, like Nuke and Magic Bullet, can read 32 bit just fine). This will output separate channels as per your render elements so you can use them in Nuke, Photoshop or whatever comp program you’re using.
So from now on you do not need to use the standard “save as” under the common tab, just work through the vray frame buffer tab to save files.
VIEWING EXR FORMAT
Open the format straight into Photoshop. You will have access to an exposure slider shown at the bottom of the window and various levels and colour adjustments.
Photoshop now half supports 32 bit (you won’t have access to a lot of tools) and almost fully supports 16 bit. Let’s just hope full support for 32 bit will come some day Adobe! Otherwise every other compositing program generally supports 32 bit, and you can push and pull levels and adjustments in the image to your hearts content.