Is there a way to do this from an IFC file and an external program or need to go to the source of the IFC file say…Revit?
Is there a way to extract the vertex of ... say a rectangle object type from an IFC file?
As shown in the other thread, there are a few ways to represent a rectangle. Some of these may use the concept of an IfcFacetedBrep, which has “vertices”, but some may not. If your IFC program defines a rectangle using a geometric representation which uses a rectangular profile, then it will not be possible to extract a single “vertex”, as a single “vertex” doesn’t exist. However, you can extract the original profile and do a bit of geometric math to figure out the coordinates of that vertex if you’d like.
If, however, the export uses a geometric representation which does use vertices, such as in Blender, then it is quite easy to extract the vertex. IfcOpenShell can help you do this.
I have written an article which guides you on how to do this - at the bottom I give a brief introduction on how to interrogate geometry:
https://thinkmoult.com/using-ifcopenshell-parse-ifc-files-python.html
Out of curiosity, what is your objective in doing this?