Is there a need for an actual IfcProject / Library element?

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Moult
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Is there a need for an actual IfcProject / Library element?

Postby Moult » Mon May 27, 2019 11:34 pm

Currently the only way to edit an IfcProject is through a dialog box UI. I wonder if it is a better idea to have it as an actual element in the tree just like IfcSite. After all, just like IfcSite, it has spatial decomposition to contain the site. Additionally, rather than have to maintain an entirely separate UI window, we can detect parameters - for example currently it is not possible to change the IfcProject "ObjectType", "LongName", "Phase", or set a "RepresentationContext" to get an IfcMapConversion for correct real world survey coordinates.

Also with an actual element maybe it is easy to swap it out with IfcProjectLibrary, rather than having the need for IfcProject to be hardcoded.

Is there interest in building an IfcProject element feature? If so, at the same time I can add the missing attributes, as well as add support for coordinate reference systems, since the inability to set a CRS is a showstopper for FreeCAD to be used on any geographically large projects right now.
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bernd
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Re: Is there a need for an actual IfcProject / Library element?

Postby bernd » Wed May 29, 2019 2:32 pm

Furthermore we could have multiple projects in one FreeCAD file. I do not see any disadvantages in this.
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Re: Is there a need for an actual IfcProject / Library element?

Postby Moult » Wed May 29, 2019 9:50 pm

Excellent! I might have a shot at implementing this.

I had a great meeting yesterday with John Mitchell, from BuildingSMART Australasia chapter - he is head of the working group that is defining how to do initial model and project setup - how to make sure everything always comes together in the right place in the world and in the right place in local project coordinates.

He was very excited to hear about FreeCAD and how it is getting some IFC features, and will be able to review our implementation of IfcProject to ensure that it fulfills the IDMs that BuildingSMART is working on.
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Cyril
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Re: Is there a need for an actual IfcProject / Library element?

Postby Cyril » Thu May 30, 2019 7:53 am

Moult wrote:
Wed May 29, 2019 9:50 pm
I had a great meeting yesterday with John Mitchell, from BuildingSMART Australasia chapter - he is head of the working group that is defining how to do initial model and project setup - how to make sure everything always comes together in the right place in the world and in the right place in local project coordinates.
You mean Jon Mirtschin no ?

About library, did you see his work about IFC library : Having FreeCAD to be the only easy to use software able to make parametric IFC objects would be a killer feature. Currently, manufacturers need to pay someone to make objects on all common software in the industry (and in my experience most of them are shitty).

About IfcProject Yorik was working on Arch Reference : I don't know how these references appear in the tree but it could be a use case for multiple IfcProject.
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yorik
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Re: Is there a need for an actual IfcProject / Library element?

Postby yorik » Mon Jun 03, 2019 6:42 pm

Until now I have failed to see a real utility to the IfcProject entity... Okay, in theory, "project != file". It's not because it's in one single file that it means it's one single project. But also, you could have the contrary, one project is made of several files (likely much more common scenario, actually) and there is nothing for that case.

This is bad design of IFC I would argue.. Do we really need to swallow and reproduce that bad design ourselves too? The question is there :D

If the thing is to be able to specify some project parameters (although, looking at http://www.buildingsmart-tech.org/ifc/I ... roject.htm, I don't see anything really meaningful), maybe we can find a way that doesn't requires an extra document object? For ex, the FreeCAD document has a "Meta" property that is a string:string dictionary. I believe no other WB uses that yet. We could maybe use it in Arch/BIM, to store some per-document settings?
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Moult
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Re: Is there a need for an actual IfcProject / Library element?

Postby Moult » Mon Jun 03, 2019 10:45 pm

Actually, there is a way to have 1 project = multiple files. I personally was not aware of how to do this since STEP as adopted by IFC doesn't allow the referencing of other IFC files in the same way that code can link together.

However, John Mitchell tells me that it is possible and the way bS endorses right now is match GUIDs, and then the ownerhistory dictates whose IFC file contains the actual content. For example, you can have one file which only contains project prepared by the client, the surveyor inherits project and specifies site in his own file, then the architect inherits site and specifies building and stories in his own file and so on.

Having an actual element simply makes the UI consistent with other spatial containers which are already elements. Also, I guess sometimes you want a project library, not a project. How should we support project library?

As for attributes, yes, project doesn't have that many attributes but the most important attribute it does have is the map conversion to specify coordinates. (I hear it might move to IFC site in the future though which makes more sense). At the very least, if project isn't an element, I'd like to implement coordinates mapping if you're ok with that :)
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Re: Is there a need for an actual IfcProject / Library element?

Postby bernd » Tue Jun 04, 2019 3:50 am

Offtopic ...

I wonder if any of the big ones is able to read or write such multiple IFC, or if there is an example (even a simple one) around. How about Ifc++ and IfcOpenShell in this regard?
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Re: Is there a need for an actual IfcProject / Library element?

Postby yorik » Tue Jun 04, 2019 2:01 pm

The multiple IFC thing is highly interesting indeed. With the Arch Reference object in FreeCAD this is becoming increasingly an issue. How do we treat that?

But I see your point, the IfcProject can be a kind of anchor point between several files, if several of them share the same project GUID we know they are parts of a same project. That makes sense... But doesn't seem very solid to me (like, how do you know the file you have is a single project or a part of a multi-file project). And indeed there is the project library problem.

BTW, doing my part to try toget rid of IfcProject ;) https://forums.buildingsmart.org/t/what ... f-ifc/1460

But I think you're right about the coordinates thing, there should be something to work with "local" coordinates. Have you looked at the App Part object? I don't really like to use it, because I don't like to have coordinates masked (I like everything in "real", world coordinates), but it might be just what you need...
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Moult
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Re: Is there a need for an actual IfcProject / Library element?

Postby Moult » Tue Jun 04, 2019 10:27 pm

I agree, the linking approach seems a little bit weak, especially as there is no URI explicitly written in the IFC. I'll find a demo of it working and ask how they achieved it. From memory they said they did it with archicad.

Let's push more on the building smart forums. I think this is the first time bS is hearing the community freely speak and it's clear we all don't agree with what they're doing.

I can go ahead with coordinates first. To start off with its simply a few more parameters to be added to the IFC project dialogue so it should be a super simple patch.
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Re: Is there a need for an actual IfcProject / Library element?

Postby yorik » Wed Jun 05, 2019 12:58 am

Just read your article about coordinates, indeed there is more complex stuff under the hood available to the IfcProject than I thought... And indeed this could be an interesting bridge with GIS, at some point we'll need to have projection system info stored somewhere...

Maybe it would make more sense to have an additional document object (a "real" IfcProject object) indeed... That would have many advantages, you can copy/paste it over, etc. And after all, if it's not mandatory on the user, why not...