CGAL users discussion list

[Thorben Kröger <>]

On Wednesday 14 October 2009 07:52:02 Marc Pouget wrote:
> One thing is surprising on this picture:
> 
> all the vertices on a "line" of the mesh should have the same
> computed differential quantities, cause the mesh is regular and the
> patches symmetric, so the estimations are only done on translates. So
> i think there may be a bug in the way neighbors are retrieved, you
> may want to check and compare the patches for vertices along the same
> "line". Note that if this is the problem, it is only related to the
> example code and not the core of the package.

I have modified my plane example to output the values computed for another 
point translated in x-direction along the plane, it should receive the same 
normal vector.

in plane_01.png, I have added the point to the right (it's located where the 
arrow originate) and it's neighors, again painted in blue '*'. The top view 
plane_03.png shows that the neighborhood is not completely the same, but 
close. I would have thought that using such a large neighborhood would be 
robust to such slight changes?

The side view is plane_02.png, the two red vectors are the ones estimated by 
CGAL for the two neighborhoods.

Any thoughts?

Cheers,

Thorben

Attachment: plane_03.png
Description: PNG image

Attachment: plane_02.png
Description: PNG image

Attachment: plane_01.png
Description: PNG image