CloudCompare forum

Hi,

I have a textured mesh (geological core) that I wish to unroll.
The tool Projection/Unroll works well for point cloud, but produce weird result when unrolling a mesh or a textured mesh.
Is there any tip I am missing here?

thanks in advance,
Jules

Nope, you are not missing anything: this tool doesn't work with meshes ;).

If it's only for visual rendering, you could sample a huge number of points on the mesh (with 'Edit > Mesh > Sample points') then apply the unroll feature.

Of course it's also possible to update the code so as to make it work with meshes...

thanks very much for the quick answer,

I don't feel ready to code this function but I'll try your suggestion with big amount of point and remeshing.
Our goal is to make visual interpretation, and if possible image processing, on the unrolled core (fossils, fractures, facies, ...), thus we need the full quality images such as produced with a texture.

Jules

I dont understand.......

I unroll meshes with texture and it works very well.....

Why you say it only work with points? For me it works with textured meshes.


BuBu

so maybe images are clearer to explain what I obtain :

original mesh with texture : unrolling previous data with cylinder gives : observe the strange horizontal lines in the left and bottom part of the image
I precise that I tried with different radius for cylinder thinking it was a probleme of intersection the mesh with the cylinder, but it doesn't help

unrolling only the point cloud and remeshing gives : The geometry is OK, but the image quality is poorer

I confirm that meshes are not handled properly when their vertices are unrolled (especially because some triangles are torn apart from one side to the other). It can only work in some very specific cases (if the mesh is opened and you are lucky).

Otherwise, if you only unroll the vertices or if you use two few sample points (and remesh) I don't think it will be very clean indeed. I was more thinking about sampling a huge number of points (i.e. 50 or 100 M) and then using the unrolled cloud "as is" so as to avoid any visual artifact. But of course it can only work for display.

OK, my meshes are not closed, they are open...

In some cases the results have been better if i rotate the mesh 90 degrees and then unroll to axis x

Bubu

From your posts I got ideas and I found a trick that does the job. You need to cut a vertical band of the core (cylinder) in order to unclose the mesh. The location of the cut is important, so make different tries to find the good one.
For our needs this will be good enough even if it's a little tricky.

Here are screenshots of the cutted core and the unrolled result.

Good idea! I hope that's not an important part though ;)

How did you manage to do that? Is there any manual or instructions to succeed that?