“…Surfaces in VRML are often not manifold, precluding application of many differential geometry operators, such as the computation of curvature. Some of the existing methods assumed welldefined manifolds or even solid models, often targeting 3D CAD models [Regli00, McWerter01, Hilaga01, Novotni01, Zaharia01, Corney02,Mukai02]. Others tried to cope with ill-defined shape representations such as VRML models [Paquet97, Suzuki98, Paquet00, Osada01, Osada02, Ohbuchi02, Zahaira02, Funkhouser03, Tangelder03].…”