How to get the irregular triangle inside the concave hull built by the ConcaveHull class？

[pucx]

By use ConcaveHull class:
https://github.com/NetTopologySuite/NetTopologySuite/blob/develop/src/NetTopologySuite/Algorithm/Hull/ConcaveHull.cs
How to get the irregular triangle inside the concave hull built by the ConcaveHull class？

[FObermaier]

Can you elaborate a bit more what you try to achieve. Maybe some sample data/image to illustrate?

[pucx]

For discrete point data, first establish the concave hull of the discrete points, and then generate contour lines based on the irregular triangle mesh inside the concave hull. So I want to get the irregular triangles inside the concave hull ,thanks.

[FObermaier]

If I understand you correctly you want to have access to the underlying (hull-)triangulation?
You can't out of the box because the parts are internal. You can -I suppose- copy and reuse the relevant code in your application:

NetTopologySuite/src/NetTopologySuite/Algorithm/Hull/HullTriangulation.cs

Lines 18 to 62 in 866a847

	public static IList<Tri> CreateDelaunayTriangulation(Geometry geom)
	{
	//TODO: implement a DT on Tris directly?
	var dt = new DelaunayTriangulationBuilder();
	dt.SetSites(geom);
	var subdiv = dt.GetSubdivision();
	var triList = ToTris(subdiv);
	return triList;
	}
	private static IList<Tri> ToTris(QuadEdgeSubdivision subdiv)
	{
	var visitor = new HullTriVisitor();
	subdiv.VisitTriangles(visitor, false);
	var triList = visitor.GetTriangles();
	TriangulationBuilder.Build(triList);
	return triList;
	}
	class HullTriVisitor : ITriangleVisitor
	{
	private readonly List<Tri> _triList = new List<Tri>();
	public void Visit(QuadEdge[] triEdges)
	{
	var p0 = triEdges[0].Orig.Coordinate;
	var p1 = triEdges[1].Orig.Coordinate;
	var p2 = triEdges[2].Orig.Coordinate;
	HullTri tri;
	if (Triangle.IsCCW(p0, p1, p2))
	{
	tri = new HullTri(p0, p2, p1);
	}
	else
	{
	tri = new HullTri(p0, p1, p2);
	}
	_triList.Add(tri);
	}
	public IList<Tri> GetTriangles()
	{
	return _triList;
	}
	}