CGAL users discussion list

[Andreas Fabri <>]

Hello,

It is not surprising that it does not look good for a cylinder.    What happens is the following:

One hole of the cylinder is considered as the outer border, and the other hole is considered
as hole.

What you can do is the define a seam on your cylindrical mesh. This duplicates the vertices
on the seam. 

There is an example  in the User Manual where we use the CGAL::SEam_mesh:

https://doc.cgal.org/latest/Surface_mesh_parameterization/index.html#title18

You combine that with the Square_border_parameterizer with the 4 corners of the
seam mesh.

https://doc.cgal.org/latest/Surface_mesh_parameterization/classCGAL_1_1Surface__mesh__parameterization_1_1Square__border__parameterizer__3.html

If the cylinder is not only topologically a cylinder, but also geometrically,
and if the seam is vertical, and if the image is periodic it should look correct.

Best,

Andreas

On 11/6/2020 6:19 PM, Andrew Cunningham wrote:

I am attempting to parameterize various flat and curved meshes using the various PMP:: parameterize_ algorithms. I note that when trying to parameterize a cylindrical mesh, none of these algorithms produce an acceptable parameterization. In fact, all the algorithms produce highly distorted U-V checkerboards. Obviously this is a difficult problem for any parameterization algorithm. I could unwrap the cylinder and transform to cylindrical coordinates , but I am looking for other ideas.

Thanks

Andrew

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