Very interesting explanation. It is all about Blender, of course, but I think the principles are generally applicable. Look at what happens with colours (at 23:00) if they are overexposed.
Render node → Tonemap → the secret of ISOrealism ;)
Interesting indeed (a bit tedious though). Luckily we can save as exr in TG.
Hah, wouldn't it be great if there was only one secret to photorealism ;D But this is a good one.
Coincidentally, I am attempting to integrate OpenColorIO at the moment because we want the Terragen render view to be able to match the look/display LUTs that are being used in film production. It should give you all some nice options to control the look of your renders.
Terragen has always had a "soft clip" feature which gives you the ability to render with a much higher dynamic range than in traditional CG. So with Terragen you already have some of the capability shown in the video. It maps scene-linear data into the view space without clipping the highlights so easily. Very bright values much greater than 1 are mapped down to a value between 0 and 1. The workflow shown in the video achieves this well.
If you take the EXR out of Terragen/Blender and work with it in Photoshop, it's too easy to lose these benefits unless you're careful.
I feel that some of the things he says in the video are misleading. Using sRGB isn't exactly "wrong" and it isn't "mangling the data" any more than the new workflow does. It's OK (although not ideal) to use sRGB for colour primaries when rendering, but they mustn't clip at 1. The most important things are to render in a scene-linear space (which both Terragen and Blender Cycles do) and then map scene-linear data into the view space in a way that rolls off highlights nicely like a camera does, to avoid clipping. That also gives you desaturation of highlights for free. All the other stuff such as contrast profiles is icing on the cake because there are all sorts of ways to do that. Having them in the render view is great, of course, and I want to post-render adjustments to Terragen's render view.
Eheheh, yeah... "The" ingredient. ;)
Every program has it's own set of secret ingredients. But many have certain protocols and render engines that take care of a large portion of options in your stead.