Thanks! These are good things to have quick answers to in docs, great points, I’ll think about how to handle that.
Quick responses here, for now, though:
Q1: Default renderer settings are good, just consider adding tone mapping for lit scenes, which improves dynamic range (reduces harsh highlights and shadows). However, you will need to set the texture encoding in most cases, see Q2.
Q2: In general texture.colorSpace needs to be set by the user, three.js cannot infer that. The default is NoColorSpace, which is correct for non-color textures like .normalMap but not for .map. See Updates to Color Management in three.js r152 - #61 by donmccurdy for more on this.
Q3: Renderer settings can be left as-is, just add THREE.OutputPass as the last pass in your effect stack. No difference on textures. I’m not sure on the current settings for the external postprocessing npm package, would see their docs for current recommendations.
Q4: I’d love to know the answer on this, too!
I agree the terrain in the screenshot does not look quite right. The three.js sky/water shaders were written before all this color management and might need further updates. If these are non-default renderer settings, I wonder if the sky/water shader is forcing you to choose those settings, and then running the terrain lighting with incorrect gamma.