Surface generation from constant depth planar contours

[praviarun]

Hi all,

I am trying to develop an application that converts a parallel set of input contours(polygons) with constant Z values to a tessellated surface mesh .The contours may also consist of holes

All available tessellation techniques like glu,delaunay talk about 2d triangulations only.
Can anyone suggest a way forward?

Best Regards,
Praveen

 

[Stephen Tashi]

I'll assume that a "hole" is a contour that has two elevation (Z) values associated with it, so it's like a vertical cliff.

If you project the contours on the XY plane and tesllate that 2-D surface so that each contour is approximated by a linked series of edges, then when you project the triangles back to the 3D surface, it will be tesselated except for the verical cliffs. You woud then have to tessellate the vertical cliffs by incorporating the vertices of the triangles that are on the contour that defines a cliff. One vertex on a contour representing a cliff would be become two vertices, one at the top of the cliff and one at the bottom. Your tesselation of the vertical face of the cliff woud have to incorporate those vertices.

Of course, that's a very theoretical sketch of a method. With cliffs that are nearly vertical, but not exactly vertical there can be problems in overflow or underflow when you project the 2D triangles back onto the 3D surface. You haven't stated your requirements for the tessellation. For example, do you want to avoid long skinny triangles?

You might have better luck with this type of question in the computer programming section of the forum or in a computer graphics forum, if you are doing this for computer graphics.