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3D registration between IFC model and 2D drawing PDF

Dear all,

Anyone had an experience of the 3D registration between IFC model and its relevant 2D drawing PDF?

In the software implementation group in buildingSMART Japan is now trying to define the common specification of the position matching between an IFC model and its 2D drawing PDF exported from a BIM software.

The 2D drawing PDF may contain the origin point, projection direction, and paper plane, to match the IFC 3D model and 2D drawing.

For example, a BIM software could export the 2D drawing PDF with the parameters of vector and position information embedded in the particular layer with in the exported PDF. Any IFC viewer can utilize the parameters to match the position and direction between imported IFC 3D model and its relevant 2D drawing PDF.

The relationship between IFC data and 2D drawing could be realized by proving IfcProject.GUID which is added into the embedded parameter in the PDF.

As you know, BIMx has already realized the integration of 3D model and 2D drawing. We would like to realize the same function by openBIM ecosystem.

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In ClosedBIM we see some solutions here, from Skanska to other solutions, mainly in FM area

But it would be good if implement it in IFC, so there would be two options:

  1. Improve IFC to be able to join/integrate PDF and IFC
  2. Build a middleware which integrates PDF and IFC (Which almost many have done this, but the first option is better)

However, personally think out of the box and I think even instead of PDF, it’s better develop preferred IFC based on “Page Layout”

Hope this suggestion helps you too: This

I cannot suggest sth straightforward way to IFC --> PDF conversion, but I can refer the path IFC --> SVG --> PDF for your purpose.
If you would like to build a solution yourself, I think the most relevant library is the IfcOpenShell; or IfcConvert should be ready to convert your IFC to SVG file with its pre-built configs. Then you can utilize many libraries in different languages to convert your SVG to PDF with all the data you need. As you may know, SVG is in XML format and you can insert as many tags as you want to make your 2D drawing rich enough. An example drawing path with some extra data (guid, area, zone name) can be like following.
<g guid="0BTBFw6f90Nfh9rP1dl_3P" type="IfcSpace" area="2.5" zone="elec" <path style="stroke:#333333; fill:#FFFFFF; stroke-width: 0.01px" d="M2.573999899999996,7.553999899999972L2.573999899999996,9.725000100000015L4.030000099999998,9.725000100000015L4.030000099999998,7.553999899999972L2.573999899999996,7.553999899999972" /> </g>

Although it is an old post, check this link to see how to generate cross-sections, and here is the python module of IfcOpenShell

Dear Mehmet, the question Mr. Adachi (@Yoshi_bSJ) asked is a little bit unclear.

  1. Do they want to show IFC (3D geometry and its related data/information) on 2D PDF? Like what some solutions like Dalux or even Autodesk BIM360 do? (which is based on converting 2D PDF/Plans to SVG)

  2. Or are they thinking about a CDE? based on PDF and IFC? In general, an information system which supports different formats like IFC and PDF, etc. (as an integrated solution)

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Dear @ReD_CoDE and @ylcnky

Thank you for your response.
What I mentioned was about option 1 (showing IFC 3D model on the 2D drawing PDF, or vice versa).
To be more precise,

  1. A BIM model is created in a particular BIM authoring software.
  2. The 2D drawing is generated from the BIM model by the software.
  3. The IFC data is exported from the software.
  4. The 2D drawing PDFs are exported from the software.
  5. An IFC viewer imports the IFC data and the relavant 2D drawing PDF, and shown in the IFC viewer.
  6. The 2D drawing representation matches with the position of 3D model without any manual adjustment operation.

For example: BIMx shows an example. We would like to do this by IFC and PDF.

It would be great if IFC could handle the information needed to transfer the mapping of drawings and model.

At the moment this is done automatically in Dalux CDE via BIM authoring software plugins or recreation of the data in Dalux when using IFC.

References between drawings are also of great value, however this can be recreated automatically.

I agree on above approach with SVG for model-cuts.
Maybe the cuts could be embedded in the IFC?

However, model-cuts are not necessarily drawings and drawings in the BIM authoring software are maybe located in the model, but can contain more detail. It can be tricky.

Still, most BIM authoring software have this data and it should be possible to transfer standardized.

It seems that both @Foldager and @ylcnky have worked in this area and hope they help you in this way.
In the near future, we will work on Page Layout, which PDF is a kind of.

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Dear all,

Yes, the automatic IFC to 2D plan conversion could be one of solution to combine the 3D model and 2D plan.
The reason why bSJ chapter is trying to do 3D position matching between IFC model and 2D drawing PDF is that the 2D drawing document contains the additional information such as annotations, symbols and perhaps some notations for the particular purpose, i.e. comments for building code checking.

Thank you @Foldager.

…, and drawings in the BIM authoring software are maybe located in the model, but can contain more detail. It can be tricky.

Yes, I think that @Foldager pointed out the same issues on that.
To clarify, please see also the attached diagram.

For example, Solibri can import the 2D PDF, and the paper space origin seems to be set at the center of Solibri’s 3D model origin. If this origin matching is done by automatically, it would be great.


As we know one of the most important issues in the industry is lack of “enough (not minimum)” data/information mounted on 2D-3D objects
However, when the PDF is popular in the industry and even is a standard, I think it doesn’t answer today needs
This is why I think “Page Layout” is a better answer

However, I think as MVP, it’s better to start from PDF approach which you follow

Regarding “building code checking”
I think the built Environment Industry is one of the messy industries with:

1. a lot of file formats
2. and less structured data

Which I think if we want to have good solutions should focus on these two issues.

Even IFC inherently has some vital issues, for instance, IFC XML doesn’t have a mechanism for rule checking, this’s why I asked this question:

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Thank you @ReD_CoDE
There will be expected the new better 2D graphics methodologies in the future, such as “Page Layout” that you mentioned.

At the moment, 2D drawing PDF is one of common digital way of the communication between the building code check agency and applicant in Japan.
bSJ’s digital building code check working group defined the roadmap for IFC utilization by the building code check organizations.

  1. Current situation: Building code check by 2D drawing.
  2. Interim goal: Building code check by 2D drawing and IFC 3D model as reference information. IFC Viewer will support the IFC 3D model and 2D drawing position matching.
  3. Future goal: IFC based Building code check with automatic code checking solution.

For the first step, they are working on making the specification of the position matching solution between IFC model and 2D drawing PDF. There was the presentation of this theme at the industry day of buildingSMART Tokyo Summit 2018.
They are planning to show some updates at the bSI Beijing Summit next fall 2019.

Last night in a Silicon Valley forum I saw an MVP that caused I think again about your approach.

As I know at the moment Bluebeam is a leader to providing PDF solutions in the (Digital) Built Environment Industry and mainly SKANSKA has focused on PDF-based solutions and use their solutions

So today found these documents that hope help with:

Thank you very much @ReD_CoDE
We will look at the solutions that you pointed out.

Last night in a Silicon Valley forum I saw an MVP that caused I think again about your approach.

any online materials about that?

That’s not very important just caused I think again about the (digital) built environment industry

What I see in BIMx solution I see in Autodesk Revit 2020 too. But I don’t think it is what you’re looking for.
It just adds PDF as a Page Layout layer [Vector] (which PDF is inherently a Page Layout File too) under your BIM model. But I don’t think it has a fully coordinated approach.

For the first milestone that you mentioned:

Building code check by 2D drawing

There are two important topics:

  1. Existing PDFs that contain “Data+Information+Model (Normally 2D models from paper scans)” which needs “data/information extraction”
    This is why the majority of solutions are based on SVG, because 2D plans as graphics in PDF stored as vector formats.

  2. 3D registration between IFC model and 2D drawing PDF: which needs PDFs generated with these requirements in mind. This means that this solution won’t work with existing PDF files in companies as silos but will work with PDFs that will develop on bSJ or bSI based on integrating PDF structure and IFC structure.

As I see in the industry those countries who have national digital projects mainly have focused on the first approach [1] but think about the second one [2] too

Hi all,
We recently published a paper on exactly this topic:

Trzeciak, M.; Borrmann, A.:
Towards registration of construction drawings to building information models using knowledge-based extended geometric hashing
In: Proc. of 26th International Workshop on Intelligent Computing in Engineering, Leuven, Belgium, 2019

Hope it helps…

Kind regards

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Dear André,
Thank you for the paper.
I’ll share the document with our working group members.

Best regards,
Yoshinobu Adachi