如何查找点是否在VTK中由2D非结构化网格定义的轮廓内？

Question

In my current problem, I want to be able to detect when a point is within a 2D vtkUnstructuredGrid or not.

I have tried using vtkSelectEnclosedPoints by making a vtkGeometryFilter and using it on my unstructuredGrid. However, the vtkSelectEnclosedPoints class is designed to check if points are located within a surface, not within a contour. Thus, when I try to apply it in 2D, I find that my points are outside of my mesh even though I know that they are located inside. This is because the class inherently works in 3D. Is there a similar class or approach I could use to detect when points are within a 2D vtkUnstructuredGrid? The code is able to know the dimension of the mesh before opening it (it is a user input).

Answer 1

So all the points in your "contour" vtkUnstructuredGrid form a single polygon? In that case you could use the vtkPolygon class, see example here . If your unstructured grid is multiple polygons, then I would still use the same thing, just iterated over all the polygons.

Answer 2

You could create a vtkModifiedBSPTree based on your 2D grid and perform raycasting (IntersectWithLine) for the points you want to test. I have used this class for terrain models triangulated as polydata, it is extremely fast and reliable.