Thanks @aothms !

Nice! If I may, I think it's really important to document assumptions. Assumption are not bad, they're required to make progress and release things, but for example:

I will update README with my ratio for thickness so that the users of this tool will be informed why was their result. Eventually I hope we will come up with a better assumption for this.

• ratio = layer.LayerThickness / total_thickness is a sane assumption, but not necessary valid, for example when openings create cut-outs that are not uniform over the layer direction.

Oh, I see. Not sure at the moment how to deal with the cut-outs when they appear. Do you have any suggestions?

• except Exception: return { "volume": 0.0 } These kind of things might also have a great impact on outcomes. Ultimately in this kind of headless processing it's a lot about trust and how to handle certain outcomes. The exception could come from many different rootcauses (and it's 100% to blame to ifcopenshell that there is no differentiation at all in exceptions) but could be: has no representation, error in applying openings, internal errors, modelling/validation errors.

Yes, I have tried to make it as simple as possible and chose to just go with the "volume is then zero".

• Also it would be good to indicate how you handle the risk of overlapping elements (either element-to-element; or geometry within an element). voxelization_toolkit https://github.com/IfcOpenShell/voxelization_toolkit (also on pip) might also be helpful to cross-reference the calculated volumes as it is not susceptible to topology/orientation errors and overlaps.

I have looked at the voxelization_toolkit and I didn't really understand the voxelize() function. If I use method=volume, will I get the same effect as we are doing right now with plain foreach element => calculate its materials volume?

I will update README with my ratio for thickness so that the users of this tool will be informed why was their result. Eventually I hope we will come up with a better assumption for this.

Done infra-plan/ifc-material-qto@64284b2

Thank you @Moult !

Very cool! Have you looked at ifcqto and ifccsv?

I have found ifccsv here https://docs.ifcopenshell.org/search.html?q=ifccsv&check_keywords=yes&area=default
But I can't find ifqto https://docs.ifcopenshell.org/search.html?q=ifcqto&check_keywords=yes&area=default#

Am I looking at the wrong place?

A qto mapping for materials and new functions to address layers might be more portable and flexible.

Not sure what you mean here? Is there an existing project doing some similar calculations that I can look into?

OK, it seems I can't find any docs for Ifc5d for me to look into. I've found some here https://pypi.org/project/ifc5d/ and here https://docs.ifcopenshell.org/ifc5d.html but there isn't much info.

Thanks, will read what's in readme in src/ifc5d directory.

Not sure if I can dedicate a time slot for contributing, but I will keep it in mind. If you have any concrete work that you think would be beneficial, it would help me a lot to see if I can organize myself for working on it.