# BuildMatrixOfSurfaceNormals

This module calculates area weighted normal vectors per node.

**Detailed Description**

For each node in the input surface mesh, find the attached faces, and average the face normal weighted by area for that node. Output a Nx3 DenseMatrix where N is the number of nodes in the input surface mesh. This matrix can be passed to [SwapFieldDataWithMatrixEntries](../ChangeFieldData/SwapFieldDataWithMatrixEntries.md) to map this data back to a vector field with the same mesh.