One embodiment of the present application sets forth a computer-implemented method for generating a three-dimensional (3D) surface model. The method includes joining a first 3D object having a first closed surface mesh and a second 3D object having a second closed surface mesh to produce an irregular surface mesh. The method further includes computing a first intersection contour for the irregular surface mesh. The method further includes removing at least one portion of the irregular surface mesh proximate to the first intersection contour to produce a first boundary. The method further includes growing the first boundary towards at least one other boundary. The method further includes connecting the first boundary to the at least one other boundary to produce a portion of a non-manifold surface mesh that comprises at least a portion of the 3D surface model.