 A given mesh may actually contain multiple unconnected shells (or bodies); each body may be partitioned into multiple connected components each defined by their edge loop boundary.To represent a hollow object, the inside and outside surfaces are separate shells.Let the number of vertices be "V", edges be "E", faces be "F", components "H", shells "S", and let the genus be "G" ("S" and "G" correspond to the "b0" and "b2" Betti numbers respectively).