Because a STL mesh input file consists only of triangular shell elements and their vertex coordinates, oSP3D does not import the mesh as it is defined in the STL file. To create a continuous FEM mesh, oSP3D automatically determines node indices and node coordinates and then associates the STL file's triangular segments with these nodes.
Due to round-off errors, vertices are assumed to be the same node if the coordinates are similar (not only equal). Two coordinates are similar if their distance is smaller than a certain fraction of the minimum triangle size.
Due to the merge of two or more vertices, some triangles may degenerate and be eliminated. As a result, the number of nodes (and also number of triangles) may be different from the original STL file.
oSP3D can export deformed geometries directly to binary STL format.