I used the blueprint node Get section from staticmesh ，and I got data from a TriPyramid.This grid should have 4 vertices and 4 surfaces.But the number of vertex arrays I get is 12.It’s hard to understand. The number of Triangles array is 12,which means the mesh has 4 faces.The number of Normal array is 12.

so I want to know why the number of vertex arrays I get is 12?

Thanks for helping!

If you look at the static mesh for the TriPyramid, it has 12 vertices, 3 for each face, instead of the 4 that are technically minimally required to create the mesh. They did this because UE4 applies mesh smoothing to the entire mesh at once, so the only way to prevent the faces from accidentally smoothing together is to provide each face with its own set of vertices.