Flatten imported IFC objects

Grasshopper
1

Hi
I have converted an IFC-file to OBJ and then imported it into a number of different layers representing a building like walls, floors, roof and windows. I would like to use this geometry as input for a building energy simulation and therefore the building elements needs to be 2-dimensional and flat. Building elements are usually kind of 2-dimensional and right now each element is a mesh that could be split into 2 large parallell faces that are rather close to each other and a number of smaller faces that are the edges of the building element. I now wonder of sombedy knows how to convert these building elements to flat single surfaces, representing the middle part of the building element?

importedifc.gh (243.5 KB)

2

Hi @max.tillberg1 ,
Which software did you use to convert the IFC to OBJ?
Was it Revit?
If so, can you create rooms (Architecture->Room) and then export the Rooms from the 3D model (File->Export->gbXML) as gbXML and import it to Rhino with Cameleon plugin. Or again to Revit and then export as .dwg. A bit too much hassle, sorry.

3

Hi
I have tried IfcOpenShell, BlenderBIM, DDS-CAD Viewer and FZKViewer and they can all convert IFC to OBJ. The problem is that I have not access to the original architectural files that are usually made in Revit and ArchiCAD and very seldom I am to get in contact with the architect to ask them export gbXML. I fully agree that that would be the best option.

4

Thanks for the reply. I understand.
Yes, this is one of the main issues for thermal analysis.
I tried to convert everything to brep, then merge all planar neighbor brep faces (in order to later extract the largest one). But this method also failed.

5

This might be what you are looking for.

importedifc_re.gh (246.5 KB)

I’m still pretty new at grasshopper so there are probably better ways of doing this. I’ve sorted the curves by area. The curves at index 0 and 1 are the outside of the walls and the curves at index 2 and 3 are the inside of the walls. I’m guessing you want the curve at index 2 or 3.

-Kevin

6

Thanks, I think this is a very good start. I still have problems with the sloping roofs and windows though.

/Max

7

Here is another version. It uses a couple of components from Pufferfish.

importedifc_re_2.gh (254.4 KB)

I am not sure what logic you can use to separate the floor decks. After I separated the horizontal surfaces and sorted them by area, the first floor deck is at index 4 and the second floor deck is at index 6.

I separated out the roof surfaces by angle. Upper and lower roof surfaces are included in this file, you could cull them by Z position.

The windows are in a separate geometry component in your file, so they shouldn’t be too difficult to isolate.

-Kevin

8

This might work for your windows.

importedifc_windows.gh (250.0 KB)

Separated bounding boxes of window frames and glass (not sure what you’re after).

-Kevin