# Thread: Determine the points at the edge of surface defined by a set of arbitrary 3D points?

1. ## Determine the points at the edge of surface defined by a set of arbitrary 3D points?

Hey Guys,

I am looking for an algorithm that can determine the points at the edge of a 3D surface (not essentially in a plane). I have an array of randomly spaced 3D points that define an open surface . I want to get the index of the points at the edge of the surface. Is there a way of efficiently doing the job? I would appreciate any help in this regard.

Thank you in anticipation.

Regards
Vj

2. Originally Posted by dotrana
I have an array of randomly spaced 3D points that define an open surface
No you don't. A set of points is insufficient to define a surface; you also need the topology. Given the topology, determining which points are edge points is straightforward (and only requires the topology, not the vertex coordinates).

3. Originally Posted by GClements
No you don't. A set of points is insufficient to define a surface; you also need the topology. Given the topology, determining which points are edge points is straightforward (and only requires the topology, not the vertex coordinates).
OK!! ... But I do not have any information on the topology... Can I define the surface through the vertex information?

4. Originally Posted by dotrana
OK!! ... But I do not have any information on the topology... Can I define the surface through the vertex information?
No. You need the topology.

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