CGAL users discussion list

[Dennis Endt <>]

Manuel Caroli schrieb:
> Hi Dennis,
>
> are you actually talking about Triangulation_2 or Triangulation_3.
> In case of Triangulation_2 you should forget about my previous answer
> and just try it->vertex(i)->point() to extract coordinates.
>
> Otherwise:
>>
>> I tried your Solution and found out that it->second isn´t always 3  what
>> I would expect if I triangulate my face before. Sometimes I got sth.
>> like 0,1,2,3,3,0 for a face.
> Why exactly do you expect it->second to be always 3? This is only the
> case if your triangulation has degenerate dimension 2. And what face
> are you talking about?
>
>> So I looked in the manual but didn`t find a explanation for this.
> Perhaps it might be helpful if you could provide more details about
> your data set.
>>
>> Can you give me a short explanation?
> - it->first gives you a cell to which the facet in question is incident.
> - it->second gives you the index of the vertex of this cell that is
> opposite to the facet in question, i.e. the only vertex that is not
> contained in the facet you are asking for.
>
> Best
>
> Manuel
Hi Manuel,

I think I misworded my Situation. I work with Geo Data Points as Part of
Buildings. The Buildings are simple 3D Polygons, partinioned in Faces
(Walls, Ground Surface, Roof).

So I want to triangulate the faces. Therefore I use the 3D Delaunay
Triangulation for every face. Afterwards I want to read out the created
Triangles with the corresponding points about to display them.

All I want to know is what is the right method for thisand how I can do
this? ;)

Furthermore I have redudant Points in the faces I would like to remove
before triangulate them. Is there any possibility with CGAL first to
detect boundary points and second to remove all other points, e.g.
Points on an edge between two boundary points or points in the middle of
the face?

Best
Dennis