The video is cool. The only weird thing is the site being treated as a building, which ideally it should simply belong as part of the site, or be called an IfcFacility, or whatever it is being refined to in future specs. This is definitely something I would like to (and will!) build in FreeCAD.
I was recently made aware that sharing IDs is actually encouraged by buildingSmart Australia (as heard from @john.mitchell ) and is not a mistake. You know how IFC has no way in its spec to reference elements from other IFC files? Well, apparently two IFC files sharing the same solution is the poor mans solution to this and it is endorsed by buildingSmart.
Here’s an example I was told: one file may define an
IfcProject element prepared by the client (and the
OwnerHistory nominates that the client is responsible). A land surveyor then writes his own IFC file that copies the
IfcProject element’s GUID from the client, but keeps all other fields blank. Then, the land surveyor defines via
IfcSites, Sub-sites, etc with CRS info, along with some topography geometry, let’s say. The
OwnerHistory of the sites and sub-sites nominate the Surveyor as the owner. Now, the architect comes into the game, creating his own IFC file. Inside the Architect’s IFC, he copies the surveyor’s site element’s GUIDs, leaving all other fields blank. He then adds an
IfcBuilding, along with some
IfcBuildingStoreys. Since the architect in this case is responsible for setting buildings and building storeys, he uses the
OwnerHistory to make himself responsible. He hands this IFC out to all the other consultants to inherit the GUIDs of the
IfcBuilding and the
IfcBuildingStoreys so that they can build their own IFC files with their own geometry.
Then, a program is capable of taking all these IFC files from different people, and based on the
OwnerHistory decides which IFC file is considered to be the source of truth. It then merges the data together.
Given this example, although the non-explicit reference kinda irks me, I have no issues with creating “partial” IFC files which inherit via having the same GUID. It looks like ArchiCAD is the first vendor I’ve seen that actually supports this workflow. It’ll be awesome if it were extended to any element. Imagine if you could define
IfcMaterial, and other consultants can start adding useful metadata to the same shared element.
I personally am looking to implement the same workflow in FreeCAD.