Custom texture mapping of surface 3D and 2D "panels"


I’m looking for some help with texture mapping (again!).
This time, I am using Custom Mapping to map a Surface map onto “panels” in both 3D and 2D.
The image below and the attached file should help to clarify what I am trying to do.

The surfaces are not made in Rhino, they are built by an external program and exported to .3dm.

Each “panel” exists as a 3D curved surface and a 2D flattened version of the same “panel”.
Custom mapping has been used to map the image from the whole surface to the individual 3D “panels” successfully, but when I subsequently try to map the same image to the corresponding 2D “panels” this does not work.
I tried converting NURBS to Mesh and this helped but is still not working correctly as you can see in the image.

I have put a few hours into this without success. Looking at the mapping in the UV Editor, it looks right for the Mesh versions, but the result is not as expected.

Thanks in advance for any help received.

mapping_test.3dm (5.1 MB)

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I’m not sure how you convert the 3D shape to the flat objects but I have an idea which could solve this issue:

Save the mesh as OBJ and reimport it to Rhino. So, the mapping UV should be baked to the mesh and you can unwrap it without to loose the UV…

Hi Micha,

Thanks for your suggestion. The conversion from 3D object to flat 2D object is done outside of Rhino by a 3rd party program.
I guess the question, therefore, is, how do I set up the mapping on the flat objects (preferably as NURBS) to match the mapping on the curved objects?


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Since each of the flat objects is a kind of rectagular surface, you could create a NURBS patch per object and you get a perfect mapping. For example this texture would follow the shape of a single patch.


For example for 10 objects you could one single texture and set scale in one direction to 0.1. Now you could set the offset per patch to 0.1, 0.2, … .


Thanks again for your suggestion, unfortunately this would not be correct - the mapping on the curved object needs to be exactly copied to the flat object. In this case I have used a mapping image, but the image could be of anything.

I have attached an additional image to illustrate what I am trying to achieve but using the NURBS surfaces (image below is mesh export from a different program). I have shown the UV Editor also.


I think you need single curved NURBS surfaces and anything should be fine. The UV would follow the surfaces edges if they are not trimmed.

Hi Micha,

Are you able to solve the issue using the .3dm file I have provided? I’m sorry, your reply does not offer much detail towards a solution. The NURBS surfaces are not trimmed surfaces in this case.

I think I understand your issue but can’t directly think of a solution. The way I understand it is that you have a double curved surface with correct mapping and a flattened version of it that basically has no knowledge about its double curved twin.

Here I fixed the mapping for the 3D version. You can see what I mean - each surface has “surface” mapping and adjusted UV. Same could be done for the 2D version.

mapping_test2.3dm (4.3 MB)

Gijs, yes I think you understand correctly. I thought, if both surfaces have same UV, then mapping would be the same. If the flat object is opened in UV editor, it can be moved but appears to be infinitely small on the UV editor image.

Micha, the mapping for the curved objects is correct in my original file i.e. only a portion of the whole image per object, like a jigsaw puzzle. What you are showing is not what I am trying to achieve here.

Thanks both

Ah, ok. What do you want to do finally? You want to print decals slices and bring them to a curved object?

Here what I get if I open the 3D version in the good old Unfold3D and let me show the current UV:

You can see the UV of the 3D object like flattened by your software. Are you looking for this?

Yes Micha, exactly.

Attached a large screenshot and a ps file of this. (27.5 KB)

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Hi Micha,

Thanks for you efforts, but the texture needs to be mapped to the flattened objects in Rhino. The flattened objects in Rhino are what get cut in real life.