Displacement using UV map affecting all maps, not just the one selected

Question

I'm relatively new to Blender and so I may just be missing something obvious. What I'm trying to do is apply different displacement modifiers to each face of an object from image textures. For example, taking the default cube and displacing each face with a different texture using UV maps. The problem I'm getting is that adding a second UV map seems to affect the area covered by the first UV map as well as the area covered by itself.

Here is what I'm doing:

1. Start with the default cube and switch to edit mode and UV editing view. (image)

2. Select one face of the cube and then open the image to be used as the UV map. (image)

3. Unwrap > Project from View (Bounds). Adjust points on image as necessary. Subdivide several times. (image)

4. Switch back to object mode and default view.

5. Add displacement modifier using the same texture image. Set coordinates to UV and select the UV map. Adjust the strength as desired, and apply. (image) (image)

6. Create a new UV map by going to Data > UV Maps and clicking the +. (image)

7. Switch back to edit mode and UV editing layout.

8. Select the new UV map from the dropdown at the top.

9. Rotate the cube 180 degrees and select the face opposite of the first one mapped. (image)

10. Open the image to be used as the second map/texture. Unwrap and subdivide. (image)

11. Switch back to object mode and default layout.

12. Apply displacement modifier the same way as before, this time using the second UV map which should cover the opposite face. (image)

Now what happens is that the second displacement modifier correctly affects the second face of the cube, but it ALSO affects the first face as well. (image)

My question is, how do I get the second displacement modifier to cover ONLY the second face?

Answer 1

When you create a second UV map in Blender, the operator (or better said, the + Button in the Mesh Data / UV Maps Panel) will create a COPY of the currently active UV map. If you rethink the steps you made, what happened is that you copied the UV map you created in the steps 1-5, and you cannot get rid of already unwrapped faces. And that's why you get the effect on both faces in step 12, you basically really have a UV map containing both sides of the Cube.

Try this: Start off with creating two UV maps on a new Cube as step number 1. But make sure you create the UV map while in edit mode and no vertex or face selected! This will create a UV map where all UVs have the coordinates (0, 0). then do the unwrapping part for both of them as you did in your description. That should ensure that both UV maps are "totally empty" when you dig into the details.