What you are looking for is called a mesh simplification/decimation algorithm. There are several of them out there, you'd just have to implement the one you choose in C# if no C# implementation exists.

Here are a few that Google turned up:

• http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Surface_mesh_simplification/Chapter_main.html
• http://www.cs.mtu.edu/~shene/COURSES/cs3621/SLIDES/Simplification.pdf
• http://graphics.stanford.edu/courses/cs468-10-fall/LectureSlides/08_Simplification.pdf

From a quick search, the only C# implementation that I found was part of Managed DirectX (predecessor to XNA), it had a SimplificationMesh class.

What you are looking for is called a mesh simplification/decimation algorithm. There are several of them out there, you'd just have to implement the one you choose in C# if no C# implementation exists.

Here are a few that Google turned up:

• Triangulated Surface Mesh Simplification
• Mesh Simplification Computing with Geometry slides
• Mesh Simplification Geometry Processing Algorithms slides

From a quick search, the only C# implementation that I found was part of Managed DirectX (predecessor to XNA), it had a SimplificationMesh class.