Displacement in negative values

I’m experimenting with the displace modifier. On the attache image, you can see the image that is mapped on the planes. The red values are 0.25, 1 and 3, so outside the 0 to 1 range. In the plane in the middle, I’m using the normals to displace. Blender takes the values and bring them down to something between 0 and 1. On the last plane, I use RGB to XYZ and I get exactly what I was aiming for but there’s a problem with both. The texture I use also has negative values on the left and these are not being used for the displacement. For me that’s a problem because Mudbox and zBrush bit use negative values in their displacement maps. So the question is, am I missing something or Blender just doesn’t support negative values? I included the blend file if anybody wants to give it a shot. For both planes we should see steps going in the opposite direction.

displacementTest.blend.zip (1.7 MB)

Is this the result you are expecting? If so, then try using a Displacement node instead of Displacement Modifier?

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In the texture panel under colors there is a clamp checkbox, unckeck it to get negative displacement.

The reason why the Normal displacement was not going out as far as the RGB to XYZ displacement is because it expects a grey-scale image and so is essentially taking the average of the colors which gives the result you see. This averaging(or some smarter conversion) is true of most single-value inputs when they are given a color input in Blender.

Also for the images you are using you should set the midlevel to 0.


Yeah, I though about it but for the research I’m doing I prefer to do it with a modifier, in case I have multiple shaders attached to the model. With a deformer it won’t be an issue.

And clamp it was! Thanks guys.

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