Schlegel diagram

A Schlegel diagram is the perspective projection of a convex n-polytope onto an (n - 1)-dimensional hyperplane through a point just outside one of its facets so that said facet encloses all other facets in the projection. It is commonly used to project polychora into 3D space for visualization, in which case the polychoron's vertices and edges are typically portrayed but with the faces and cells left out.