3Open Geospatial Consortium.Open GIS City Geography Markup Language (City GML)Encoding S t a n d a r d V e r s i o n 2.0.0[S/O L]. h t t p://w w w.opengisspatial.org/standards/citygml .
4Léon Van Berlo.BIMserver Documents[OL]. https://github.com/opensource BIM/BIMserver/wiki .
5Florian Schroder,Patrick Robbach.Managing the complexity of digital terrain models. Computers and Graphics . 1994
