This (https://www.youtube.com/watch?v=hmy0BIKgxp8)and this (https://www.youtube.com/watch?v=5umbUNOT6HI&feature=youtu.be) tutorial have been great starting points, but there are some unanswered questions.
Take a look at the attached images (artwork by Wouter Gort and Paul Dave, respectively) . I'd like to point out the radius (spread) of the edgewear which is not easily achieved using a curvature or occlusion mask (or is it?). You can see my progress so far in the attached image where I am [sum] blending the curvature mask and a bitmap texture.
The question is:
1. How to grow the selected curvature mask to effect a larger radius?
No solution exists
2. How to use the masked area as a bump map to give the impression that the painted area is raised (on top of) the metal area
EDIT: Why can't a color adjust node be passed into a bump channel?
Answer: Maybe in future release
Answer (https://www.youtube.com/watch?v=XfSiac7Lw2I) to #2 (partial):
Answer to #1: advanced edge-wear in post (Photoshop)
I am as well wondering why some nodes can't be passed to others, when it seems it should work. Would be nice to have a reference graph of which ones can be passed to which, and which inputs are looking for what type of data.
So I didn't realize this - although it makes sense - but the renderer really has to chew on mid-gray values when processing layered textures. In addition, the product and interior rendering options do not converge on identical solutions after a comparable render time (see image 1 and 2).
For example, in the first image, there is simply a plastic material in the label of a metallic material. Render cranks out in ~1:30. In the second image, the material graph (see image 3) contains some additional bump and roughness data to define the material layers and takes 2 hours to reach the sample quality of the first image (see image 4). However, there is much more complexity in the image due to brightness / contrast properties of the texture that is driving the surface imperfections. Specifically, the texture had a brightness of 1 and contrast of 10 (see image 5), but with a brightness of 10 and contrast of 10 (see image 6), the render resolves *much* more rapidly (see image 7).