set EdgeVisibilityOn when draw VTK_HEXAHEDRON

I have a question about EdgeVisibilityOn when draw VTK_HEXAHEDRON, why a little edge will be show in the picture? In SetRepresentationToSurface mode, the small edge should be hide.

This looks like the rendering artifacts that can occur when using coincident topology resolution parameters (see e.g.

Thanks you Andreas, SetRelativeCoincidentTopologyLineOffsetParameters can solve the problem