# Re: is there a simple way to create a surface from set of 3D points?

• To: Donna L Gresh <gresh@xxxxxxxxxx>
• Subject: Re: is there a simple way to create a surface from set of 3D points?
• From: Bill Hibbard <billh@xxxxxxxxxxxxx>
• Date: Fri, 8 Nov 2002 15:22:09 -0600 (CST)
```Hi Donna,

> I am just getting started using VisAD and what I would like to do is to
> create a surface representation (triangles) of a set of *3D* points. Is
> there a straightforward way to do this? It seems that the Delaunay methods
> are going to want to create a tetrahedralization for me instead. I expect
> my 3D points to define a gently sloping surface in 3D (something like a
> topographic landscape). Are there any examples of doing this?

If one of your coordinates is a function of the other two,
say Z values depend on X and Y values, then construct an
array float[2][number_of_points] consisting of the X and
Y values and pass it to the constructor:

DelaunayWatson delan = new DelaunayWatson(float[][] samples);

Then construct an array float[3][number_of_points] consisting
of the X, Y and Z values and pass it to the constructor:

Irregular3DSet set = new Irregular3DSet(type, samples,
coord_sys, units, errors, delan);

Note coord_sys, units and errors can all be null, and type is
a RealTupleType "(x, y, z)". This will construct a set of
triangles in 3-D.

If there is no dependency of one coordinate as a function of
the other two, then you need to define your own triangle
topology as a DelaunayCustom.

Good luck,
Bill

```
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