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[Manu Kaul <>]

Thanks Monique and Olivier. Will look into the tutorials. Its just that I haven't done much generic programming either, so wondering what the 
learning curve will be in that case.

On Mon, Sep 10, 2012 at 10:26 AM, Olivier Devillers <> wrote:

Le 9/9/12 8:18 AM, Manu Kaul a écrit :

Hi all,
I used the "Triangle" library from http://www.cs.cmu.edu/~quake/triangle.html <http://www.cs.cmu.edu/%7Equake/triangle.html> by Jonathan Shewchuck to generate a Delaunay triangulation

of my raw x,y,z points. I am trying to create an indexing structure and some distance bounds that make the shortest path calculation on a
terrain faster + some other queries like range queries, and k-nearest neighbour queries as well.

I noticed that in order to do some of these things I might need CGAL, but I understand that the learning curve can be quite steep.
The things I need to do are :
1. Generate TINs at multiple levels of details by introducing Steiner points.
2. Being able to access the triangles and its adjacent triangles in raw form (like 0 1 2 vertices of triangle in counter-clockwise format)

so that I can feed it to a "Chen and Han" shortest path implementation by O'Rourke (http://cs.smith.edu/~orourke/ShortestPaths/ <http://cs.smith.edu/%7Eorourke/ShortestPaths/>)

3. Have the ability to compute the slope of each triangle and also all its interior angles.
4. Need to be able to *project* onto the terrain the 3D euclidean line between any two points of the terrain.
5. Generate a Voronoi diagram from the Delaunay (Triangle generates this too)

2 Triangulation of a terrain is what you need:
http://www.cgal.org/Manual/beta/doc_html/cgal_manual/Triangulation_2/Chapter_main.html#Subsection_37.5.2

4 The triangles intersected by the vertical projection of a line on the terrain are given by
http://www.cgal.org/Manual/beta/doc_html/cgal_manual/Triangulation_2_ref/Class_Triangulation_2.html#Nested_type_Line_face_circulator

5 use "dual" fonctions of vertices and faces

3 are just basic computations

1  you have to manage levels of details yourself. CGAL triangulation supports insertion and deletions.

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