…What is CityGML and what about the extension for GeoBIM?
CityGML is a relatively young open standard for modelling cities. This standard originates in the geographic world (GIS). The GIS world is known for its 2D maps, but has recently started adding 3D objects. Agreements have been defined in CityGML about how roads, buildings, water, vegetation, green spaces and so on are described. Because this is documented for complete cities, the level of detail describing a building in CityGML is rather limited (not nearly as detailed as in IFC). However, it is possible to define expansion sets in CityGML. This makes it possible to add specific information to a CityGML model (for the nerds: comparable to Psets in IFC). The initiator of the GeoBIM extension is BIMserver open source. This CityGML extension for GeoBIM information enables IFC data to be added to the buildings in CityGML. The BIMserver software export to CityGML facility, adds the IFC information according to this official GeoBIM extension.…
…Is that all?
Another popular feature is clash detection on the (merged) IFC data and the option to ‘subscribe’ to changes in (part of) the model.
Other users very much appreciate the automatic up-to-date KML interface. This enables clients to monitor the project progress in Google Earth. The exports to CityGML, ifcXML, Collada (for Sketchup) are also very popular. The O3D/WebGL functionality enables you to inspect BIM models in your web browser without having special IFC software installed on your PC.
The more technical users are enthusiastic about the Query and filter options for the IFC data. Simple pre-programmed queries such as ‘give me the 2nd floor only’ or ‘give me all the windows’ are widely used.
But you can program more complex queries yourself, such as ‘give me all doors on the 3rd floor that are wider than 900 mm’ using the advanced query function.
The nerds among us consider the various interfaces (web user Interface, REST interface and SOAP) and working with an EMF framework wonderful.…