[vtkusers] Can vtkSelectEnclosedPoints->IsInside work for concave surfaces?

[lynx.abraxas at freenet.de]

Dear Jothy,


On 05/08/10 11:11:11, Jothy wrote:
> Hi all,
>
> I wonder whether this vtkSelectEnclosedPoints->IsInside works well for
> concave 3D surfaces!

I'm  not  sure  about the code implementation behind this but normally a check
for a point being inside is:
shoot a ray from the point and count its intersections with the surface to  be
checked  against.  If  the  amount of intersections is odd the point is inside
otherwise outside (if the surface is manigfold and closed).

> From the docs, I found it assumes the surface is closed and manifold.
>
> Or, is it better to use vtkPolygon->PointInsidePolygon, which uses ray
> tracing to determine this.

Not sure if vtkPolygon can hold vtkPolyData. Could it be a 2D check?

Hope this helps.
Lynx