IFC Properties for Geo-referencing in Cesium Ion

Cesium ion
1

Hello,

I would like to know which properties within an IFC file are used for geo-referencing when it’s converted to 3D Tiles using Cesium Ion. I have several geo-referenced files, but almost none of them are placed at the correct position or with the correct scale, so I’m wondering what the problem could be.

Thanks a lot!

Best regards,
Luca Rath-Heel

2

Hi,

Can you please share an asset id or some sample data with us, we can take a look at what could be going wrong. Please also provide the input that you are passing as the EPSG code when picking the tiling options.

Thanks,
Ankit

3

Hi,

thanks for your quick reply!
I have uploaded the same file three times:

  • asset 3663336 (no epsg)
  • asset 3663335 (epsg 4326)
  • asset 3663332 (epsg 2056)

I kept the default values of all the other options.
The correct coordinates are provided in the IFCSITE property of the IFC file.

Thank you for having a look!

Best regards,
Luca

4

Hi Ankit,

we are currently evaluating using Cesium Ion in production and this is an essential part of our usecase, therefore I would highly appreciate if you could take a look and let us know, if this is a problem with our assets or with your converters.

Thank you very much!

Best regards,
Luca

5

Hi,

The Cesium tiler doesn’t currently use the IFCSITE property when processing files. Instead, it relies on the coordinate system specified in the UI or in the IFCPROJECTEDCRS property. Support for IFCSITE may be added in a future update, so feel free to keep an eye out for that.

Regarding the file you’re trying to tile asset 3663332 should have worked when EPSG 2056 was provided, but I noticed it’s not appearing in the correct location. I’ve opened an issue with our team to investigate further.

7

Hi,

thanks for having a look!

Best regards,
Luca

8

Hi there,

are there any updates on this topic?

Thank you!

Best regards,
Luca

9

Hi,

Supporting IFCSite property is still on our teams to do list. The current estimate is for the October monthly release.

Our investigation into asset 3663332 with EPSG 2056 determined that the asset had a northing and easting offset in the file that was required to position it in the correct location. The Cesium ion interface does not currently suppport a way to provide this information. The enhancement to use the data from IFCSite willextract that additional data from the file and pass it to the tiler to correctly locate the asset once it is implemented.

Thanks for your patience with this.

10

Hi,

alright, thanks for the update!

Best regards,
Luca

11

Hi Luca,

We’re actively investigating this. We’re noticing that the exported point information doesn’t look like coordinates needed for that EPSG code. We think it has to do with how ArchiCAD exports the IFC. There are a few ways to export to IFC such as “Project Survey and Point Origin,” “Project Origin only”, etc.

In the meantime, we’re working on getting ArchiCAD access to thoroughly test the workflow from exporting IFC to our tiler ingestion with automatic geolocation.

Thanks!

-Cory

12

Hi Luca,

Would you be able to share your ArchiCAD project, even if just a subset? We’re seeing what looks like some uniqueness in the way ArchiCAD exports IFC that we’d like to test solutions to.

Thank you!

13

Hi Cory,

Thanks a lot for looking into this! Unfortunately, I don’t have access to the ArchiCAD project itself, so I’m unable to provide it. Would it perhaps work if you import the IFC file into ArchiCAD instead? According to the ArchiCAD documentation, you can create a new project from importing an IFC file, which should presumably restore the relevant project settings from the IFC. But thats just a guess.

Best regards,
Luca

14

Hi Luca,

We were able to tile your dataset. The geolocation also looks correct to me. The patch to handle ArchiCAD’s method of export will likely make the December release. If you’d like, you can DM me and I’ll send you the tileset for evaluation.

Thanks!

-Cory

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