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Displacement maps


SeanOSkea

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I’m trying to get a handle on displacement maps. I watched the recent VW youtube video on Maxwell render files and downloaded a bunch to play with. I even got the shingles that Jim recommended in an earlier post. I have very strange results.

In VW (very high, 1” 12”sq) there was a strange corrugation in the image and a V-shaped valley in the middle of the shingle. I used the same files in c4d (10 subs) and received the expected result. I tried many setting variations in VW and could not get the same results as the c4d render.

So I decided to do some test files. Went into PS, filled with 50% grey. Put an almost white rectangle next to an almost black rectangle. In c4d they rendered as you would expect with the white rectangle extruding and the black receding. In VW both rectangles extruded. The only difference was a small valley around the edge of the black rectangle. I put the d-map in the color channel for reference.

I’m hoping I’m doing something silly.

Sean

Win8.1 i7-4770 3.4 16GB GTX 650Ti VW 15 sp2

Edited by SeanOSkea
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Sean-

I think what you're seeing in VW is that the object you applied the displacement material to appears to be fairly thin and two-sided - so the black receding parts from one side are intersecting with the black receding parts from the other side, which are going in the opposite direction. This results in the weird X-shaped intersecting displacement.

Try applying that displacement texture to a thicker wall.

As far as the stair-stepped displacement in the VW texture - I did some research into this with VW2014 and I think I found that using 16 or 32-bit displacement maps (instead of 8-bit) will give smoother displacements in VW.

Quote from Maxwell Render online support file:

It is recommended to use at least a 16-bit displacement image to create a smooth displacement, because 8-bit images may not contain enough gray levels (they contain only 256 height levels), so you may end seeing a stair-stepping effect if using 8-bit maps. (...)

HTH.

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Thank you!

This is the most clear and conclusive answer I've ever received from a forum post! Of course that's what's going on. I can't believe I didn't see that. In C4D I just selected the one polygon face to apply the texture to, that's why it didn't happen there. And the funny rectangle test (I realize I posted the wrong image)That's why the black rectangle was slightly shorter than the white--it was shorter by the thickness of the extrusion.

Thanks for the bit-depth tip too. However, when I tried to recreate the problem for Jim, and couldn't--I must have made a slightly thicker extrusion--it looked fine. So I think the washboard was also a result of the double sided texture.

Thanks to both of you

Sean

Edited by SeanOSkea
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