How to define GPS coordinates for a sign in an IFC model

R by Rick_Brice on 18 Mar 2025, edited 18 Mar 2025 #

I have some sign data which includes sign type, dimensions, and location. Location is a GPS coordinate.

Using IfcSign, IfcSignType and Qto_SignBaseQuantities, I can model the sign information well, but I'm a little stuck on locating the sign using its GPS coordinates. How would I do this?

M by Moult on 18 Mar 2025 #

@Rick_Brice I'm not aware of any property set that stores EPSG:4326 WGS84 lat longs. The IfcSign however will have an ObjectPlacement and therefore that XYZ can be converted using the IfcMapConversion to the IfcProjectedCRS coordinate system, or alternatively to the IfcGeographicCRS.

R by Rick_Brice on 18 Mar 2025 # +1 votes

Thanks - I just discovered this https://www.buildingsmart.org/wp-content/uploads/2020/02/User-Guide-for-Geo-referencing-in-IFC-v2.0.pdf.

The GPS coordinates are from a lidar scan. I need to devise a project coordinate system to locate the sign locally and then tie it to the IfcProjectedCRS or IfcGeographicCRS. If the lat/lon needs to be retained, for information (and easy of look-up) perhaps that's the job of a custom property set.