Hello all,
I'm currently making a PBT (polybutylene terephthalate) keycap shader. The tops are more roughly textured and generally less shiny looking than the usual ABS (acrylonitrile butadiene styrene) variety. Since I'd like the keys to hold up to closeup shots, simply cranking up glossyness on specular won't do. The detail needs to be there. At the moment the shader is set up with displacement mapping and I have it looking more or less the way I want (with PBR):





The problem is of course performance. The shading quality needs to be set very high to stop fine displacement detail from jittering during animation. Pixel samples are 8x8 at minimum. It all renders well enough at quarter HD res, but my system is maxed out at 16GB RAM and it doesn't look like there is enough headroom to render at 1080p.

I'd like to replicate the same look I currently have with bump mapping. Is it feasible or is it necessary to dice up the geometry to capture very fine details like this? What is the proper way of feeding displaced normals to the Physically Based Specular VOP. I'm only having limited success with that at the moment.
Cheers!

I don't see why you are deliberating so much over what seems like a simple decision. Bump mapping ill yeild the same results for less render time and computation. I'd say do it

Lower your Tile Size. Try 8 instead of 32.

EDIT: For this case I would have used bumpmaps as well tho cause I doubt you will notice the true displacements.

Sorry if I wasn't clear. I do want to use bump-mapping, but I'm having trouble matching the look of real displacement. Examples:

Actual displacement:



Turning off True Displacement on the mantra node:



Disconnecting displacement in the shader and piping displaced normals into the Physically Based Diffuse and Physically Based Specular VOPs:


The effectiveness of the bump falls off very quickly in z space.

I find Normal maps much much better for this kind of high-frequency detail.