Problem with Delaunay triangulation

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Problem with Delaunay triangulation

coz.mars123
Hi all,

I need to create a Delaunay triangulation of a curved surface from a .ply
mesh file. I also need to use terrain type (CGAL::Projection_traits_xy_3)
for my application.
For this, I have succeeded to read all vertex from the .ply file and to
create the Delaunay triangluation by dt.insert() function.

However, the mesh created has unintended faces, like the attached image.
Does CGAL have any solution for this problem ? Thank you for your help.

Mars
<http://cgal-discuss.949826.n4.nabble.com/file/t376147/capture_curve_surface_.png>
 



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Re: Problem with Delaunay triangulation

chrism
When you iterate over the faces to out put, only iterate over the finite faces. 

On Thu, Oct 31, 2019 at 14:46 coz.mars123 <[hidden email]> wrote:
CAUTION: This email originated from outside of the University of Saskatchewan. Do not click links or open attachments unless you recognize the sender and know the content is safe. If in doubt, please forward suspicious emails to [hidden email]


Hi all,

I need to create a Delaunay triangulation of a curved surface from a .ply
mesh file. I also need to use terrain type (CGAL::Projection_traits_xy_3)
for my application.
For this, I have succeeded to read all vertex from the .ply file and to
create the Delaunay triangluation by dt.insert() function.

However, the mesh created has unintended faces, like the attached image.
Does CGAL have any solution for this problem ? Thank you for your help.

Mars
<http://cgal-discuss.949826.n4.nabble.com/file/t376147/capture_curve_surface_.png>




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Chris Marsh, PhD
University of Saskatchewan
chrismarsh.ca

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Re: Problem with Delaunay triangulation

MaelRL

Hello,

The issue is not coming from finite or infinite cells, but rather that the Delaunay triangulation is a triangulation of the convex hull of your point set. Note that in addition, you might not obtain the same combinatorics as in your input data (except if that data already comes from a Delaunay triangulation).

To get just the faces you want, one way might be (looking at your screenshot) to partition the set of faces that are on the border into connected components whose borders have edges with a significant change in normal. A face on the boundary will be characterized by being incident to one finite and one infinite cell.

Best,
Mael

On 02/11/2019 11:32, Marsh, Chris wrote:
When you iterate over the faces to out put, only iterate over the finite faces. 

On Thu, Oct 31, 2019 at 14:46 coz.mars123 <[hidden email]> wrote:
CAUTION: This email originated from outside of the University of Saskatchewan. Do not click links or open attachments unless you recognize the sender and know the content is safe. If in doubt, please forward suspicious emails to [hidden email]


Hi all,

I need to create a Delaunay triangulation of a curved surface from a .ply
mesh file. I also need to use terrain type (CGAL::Projection_traits_xy_3)
for my application.
For this, I have succeeded to read all vertex from the .ply file and to
create the Delaunay triangluation by dt.insert() function.

However, the mesh created has unintended faces, like the attached image.
Does CGAL have any solution for this problem ? Thank you for your help.

Mars
<http://cgal-discuss.949826.n4.nabble.com/file/t376147/capture_curve_surface_.png>




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Chris Marsh, PhD
University of Saskatchewan
chrismarsh.ca