IFC to CityGML names are changed into genobj:GenericCityObject

Hi @007fkj,

Thanks for your question! Most translations will work fine being generated from reader to writer with no transformers, but because of the nature of IFC and CityGML data, which is hierarchical, this translation will need a more complex data translation involving more transformers.

IFC and CityGML differ quite a bit in how their features are grouped, such as in how IFC Doors are the children of Openings, which in turn are the children of Walls, while in CityGML, Doors are children of Walls. Go to the BIM to GIS (Intermediate) tutorial, download the completed workspace, and plug your IFC file into the workspace and run it. It should run successfully for you without changing anything else.

 

 

The transformation in that workspace is what is needed to convert IFC to CityGML structure, and it will write out your data in the desired feature types as opposed to a single GenericCityObject feature type.

Hi @007fkj,

As @JovitaAtSafe mentioned there can be a lot to the transformation from IFC to CityGML. The trouble with the conversion is that you need to manually rename the layers/features to match exactly that if the CityGML Schema.

 

For example an ExteriorWall in IFC need to be directed to the WallSurface feature type from CityGML. It will also need to have an attribute 'gml_parent_id' which matches the gmlid of the 'Building' to which it belongs.

 

This link should help with which geometry types, and which lod names, go with which feature types: https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/citygml/Tutorial/writing_citygml_from_fme.htm#

 

The 'CityGMLPropertySetter' can be used to define the geometry names and lod names.

 

This template workspace can be a good starting to create an LOD2 building: https://hub.safe.com/templates/citygml-create-building-lod2 but the article linked by @JovitaAtSafe has a lot of important information too which should help bring it all together.

Yes it was helpful thanks for sharing but is there anyway available to convert IFC layer information into objectType and name in CityGML?

You should be able to translate layer information into the desired feature types by transforming the data and connecting it to the corresponding feature types. I noticed this document on Writing CityGML from FME that I think might help clarify some things like the GenericCityObjects feature type.