The above, plus a "toon shader" to make those colour patches. There seems to be some outlines in there as well? I've only seen this done in 2D, in a vector-to-pixel-art tutorial: - http://2dwillneverdie.com/tutorial/vector-to-pixel-building-your-sprites-in-adobe-illustrator/ -…
In Step 1 of the tutorial how do you figure out the correct pixel density ? When following the tutorial and creating a cube and setting the pixel per centimeter to 204 the cube shell shrinks, in that case the first step of the tutorial mentions that the pixel density was off and would need adjusting, how do you calculate…
Well, that's simply how Shadows/Highlights operates - basically working as an edge detection filter, similarly to Unsharp Mask. Instead you need to use methods affecting all pixels the same : Levels, Brightness/Contrast, Curves, and so on.