[vtkusers] landscape Delaunay triangulation

[Pedro Miranda]

Hi Sebastian
First let me thank you for your reply.

As I told in my first message I'm new to VTK, but I also forgot to tell
that I'm also new to CG.
Let me explain better what I want to do so that you can tell me if
delaunay2D is really what I need.

I have some data from field capture representing landscape (terrain) in
ascii format, plain xyz.
What I need is to model the terrain to show as 3d landscape, actually I
need to regenerate the terrain( or landscape) as a
triangle mesh, so that I can save it as a directX file (.x).

The best help I found in the web was Paul Bourke homepage
(http://astronomy.swin.edu.au/~pbourke) and is Efficient Triangulation
Algorithm Suitable for Terrain Modeling
or  (http://astronomy.swin.edu.au/~pbourke/terrain/triangulate/).
And after your reply I when to is source again and saw that he is actually
doing 2d delaunay and not 3d as I taught.


I've changed the source but it is still very slow when you have large
amount of data.....like I have.

I would apreciate any help or direction.

Thanks a lot............
Pedro.






"sebastien MARAUX" <maraux at ondim.fr>@public.kitware.com on 12/18/2002
15:41:20

Sent by:  vtkusers-admin at public.kitware.com


To:   "Pedro Miranda" <Pedro.Miranda at edinfor.edp.pt>, "vtkusers"
      <vtkusers at public.kitware.com>
cc:
Fax to:
Subject:  Re: [vtkusers] landscape Delaunay triangulation



Hello,

It is a landscape, so height component is not to take
into account for triangulation. A simple delaunay2D
triangulation should do the trick if you only need
a surface, as I would expect for a landscape.
Delaunay3D will try to create a 3D object,
which is not what you want, isn't it?

And if you have numourous points, as I expect for a
landscape, you would do better by triangulating your
landscape "at hand", creating 2 arbitrary triangles for
each square (just do a simple loop, add points to a
vtkPoints when it is not done, and create 2 new
VTK_TRIANGLE cells for each square from points ids),
it will be far faster as number of points grow.

If you think about decimating your mesh after, you may
think about a delaunay insertion method right from
the creation of your mesh.

Seb


----- Original Message -----
From: "Pedro Miranda" <Pedro.Miranda at edinfor.edp.pt>
To: <vtkusers at public.kitware.com>
Sent: Wednesday, December 18, 2002 4:07 PM
Subject: [vtkusers] landscape Delaunay triangulation


>
> Hi,
>
> I've some landscape data in an ascii raw xyz format and you'd like to
> reconstruct the terrain surface as a triangle mesh.
>
> Data example:
>
> -51685.689746;187747.836910;-0.100000;
> -51687.829454;187747.825518;-0.100000;
> -51688.772546;187746.820482;-0.100000;
> -51684.526254;187746.843090;-0.100000;
>
> I've been researching Delaunay triangulation and Voronoi tessellation and
> found VTK (thank god I did) but being new to this library I'm still a
> little lost among all the classes and potential of this library.
>
> Never the less I found that vtkDelaunay3D and/or
> vtkSurfaceReconstructionFilter might the classes that I need to use to
> accomplish that task.
>
> What I need is some guidelines from anyone who had experience in
landscape
> reconstruction from that kind of data using VTK.
>
> Thank you in advance.
>
> Pedro
>
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