Empty list of quantity sets in IFC-file (Ifcopenshell)

[elisemunche]

Hi!

I am trying to write a code that extracts the quantity sets from an IFC-file for IfcBeam and IfcColumn.
I have this code that works perfectly for most of the IFC files I have tried:

import ifcopenshell
from ifcopenshell import util

ifc_path = r"C:\Users\elisemun\Documents\GitHub\vsc_test\test_ifc_revit.ifc"
ifc_file = ifcopenshell.open(ifc_path)

all_elements=ifc_file.by_type("IfcBuildingElement")

#Wanted element types
LB_elements = []
for element_type in ['IfcBeam', 'IfcColumn']:
LB_elements.extend(ifc_file.by_type(element_type))

#Qtos (Quantity set)
info_elements= [ifcopenshell.util.element.get_psets(element,qtos_only=True) for element in LB_elements]

However, I have some IFC files that give me the result info_elements=[ {},{},{}.....{}]. I assume this means that there is no value here with the method I am using. When looking in the IFC files that do not work with my code, I cant seem to find the entities (amongst others): IfcQuantityArea and IfcQuantityLength, like I can in the files that do work.

So my question is, does anyone know how I can reach the quantities in such a file by using Ifcopenshell?

Thank you!

[aothms]

Quantities (and property sets) are not guaranteed to populated in a model (or generated consistently for that matter). Luckily ifcopenshell provides the tooling to generate a lot of quantities from the geometry. https://github.com/IfcOpenShell/IfcOpenShell/blob/v0.7.0/src/ifcopenshell-python/ifcopenshell/util/shape.py

[elisemunche]

I see! Thank you so much for the response, I am looking into it now :D
Do you also by chance know what is meant by "geometry" as requirements in several of the definitions? @aothms

[aothms]

The result of geom.create_shape() / geom.iterator.get (with USE_PYTHON_OPENCASCADE to false, which is the default).

>>> import ifcopenshell.geom
>>> import ifcopenshell.util.shape
>>> f = ifcopenshell.open('acad2010_walls.ifc')
>>> elem = ifcopenshell.geom.create_shape(ifcopenshell.geom.settings(), f.by_type('IfcElement')[0])
>>> ifcopenshell.util.shape.get_volume(elem.geometry)
0.9425983811263173

[elisemunche]

I see, thank you! I have been playing around with the code for a while now but cant seem to understand how to extract the cross section areas and the length of the elements using the library. May I ask if you have any ideas? From: Thomas Krijnen ***@***.***> Sent: Tuesday, March 28, 2023 1:58 PM To: IfcOpenShell/IfcOpenShell ***@***.***> Cc: Elise Munch-Ellingsen ***@***.***>; Author ***@***.***> Subject: Re: [IfcOpenShell/IfcOpenShell] Empty list of quantity sets in IFC-file (Ifcopenshell) (Discussion #2914) The result of geom.create_shape() / geom.iterator.get (with USE_PYTHON_OPENCASCADE to false, which is the default).

>> import ifcopenshell.geom >> import ifcopenshell.util.shape >> f = ifcopenshell.open('acad2010_walls.ifc') >> elem = ifcopenshell.geom.create_shape(ifcopenshell.geom.settings(), f.by_type('IfcElement')[0]) >> ifcopenshell.util.shape.get_volume(elem.geometry)

0.9425983811263173 — Reply to this email directly, view it on GitHub<#2914 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/A5TC3P26RALODHBZ34MYAA3W6LG53ANCNFSM6AAAAAAWKK6Z3Y>. You are receiving this because you authored the thread.Message ID: ***@***.******@***.***>>

[aothms]

All attributes are available on the entity instances, so look at Representation Representations Items Depth, or loop over ifcopenshell.file.traverse(my_column) until you find what you need

[Moult]

I've seen this come up in a few places on how to get extrusions specifically (they are one of the most common representation items) or cross sectional profiles so this might help 260eb31

[aothms]

That's great as it also handles boolean operands which I didn't discuss

[arunkvijay]

I've seen this come up in a few places on how to get extrusions specifically (they are one of the most common representation items) or cross sectional profiles so this might help 260eb31

Thanks @Moult, this is very helpful. There is a small spelling mistake in L301 (to be changed to extrusions). Should I submit a PR for this?

[aothms]

@arunkvijay yes please :) according to the interpreter that's not a harmless spelling mistake, but a NameError. Good catch :)