1. A computer-implemented product including instructions embodied in a non-transitory computer read-able medium that, when executed by a processor, cause the processor to: in response to input selecting one of a plurality of faces of a boundary representation model of an object, identify boundary edges of the model outside the one of the faces not separated from the one of the faces by an intervening concave or convex edge, the boundary edges defining a perimeter of a topological feature containing the one of the faces, identify a set of the faces, including the one of the faces, contained by the perimeter, and generate output highlighting the boundary edges and set of the faces of the topological feature.