Including metadata in gltf

Hello Kyle

I started to set up a prototype for converting the results of our 2D hydrodynamic model in a compatible format for Cesium. For doing that I had to switch to Unreal, because I saw that, at the moment, there are more Cesium features available there than in Unity.

Currently I am trying to find a way for converting the mesh of our hydrodynamic model in a glTF object and I manage to do it using the “rgl2gltf” package in R. Now the next step would be appending the model results to the glTF object. In this regard, I have a few questions:

  • Is it correct that, currently, Unreal supports metadata integration only via the “EXT_feature_metadata” extension? I tried loading a glTF object that uses the “EXT_mesh_features” from Cesium ion to Unreal but the “Autofill” function of the “Encoded Metadata component” didn’t work.
  • The R-package “rgl2gltf” does not allow attributes to be integrated in the glTF object. I tried the Visual Studio Code Editor but it does not recognise the EXT_feature_metadata extension either, so I was wondering if you could recommend another glTF Editor – or more in general another workflow/pipeline - that can handle this.

Thanks in advance for any hint.


Hi Manuel,

I don’t have an answer for your second question, but I can answer the first.

Currently yes, Unreal only supports metadata integration via EXT_feature_metadata. But we are also working on supporting EXT_mesh_features and EXT_structural_metadata, which we are looking to complete in the next few months. This would include deprecating support for the older extension and the related API.


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Thanks for your answer! Currently, I’m still working in R on integrating my metadata in a gltf file with the EXT_feature_metadata extension, because I want to go on working with Unreal. I’m following the documentation but I am still struggling with getting it to work. Unfortunately, the gltf Validator I am using doesn’t support the extension anymore. Can you maybe point me to a gltf sample containing the EXT_feature_metadata, a feature table etc.? That would help me a lot!

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Some examples for EXT_mesh_features and EXT_structural_metadata can be found in the 3d-tiles-samples repository at 3d-tiles-samples/glTF at main · CesiumGS/3d-tiles-samples · GitHub

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Thanks Marco. What about EXT_feature_metadata? Is the extension still supported by Cesium ion? When I try to upload my gltf, i get following error: “Something went wrong with this asset. To report this issue, please email with the asset ID: 1837719. To help resolve this faster, include any relevant information about your data, such as what software you used to export it.”

It is not clear whether this error is caused by the given extension, but I think that the extension is currently not supported as an input for ion.

More generally: EXT_feature_metadata was a draft extension proposal, and support for it (in its early versions) has been added internally, for example, to Cesium For Unreal. But this draft extension is now replaced by EXT_mesh_features and EXT_structural_metadata. Janine already mentioned that the work for supporting it in Cesium For Unreal is in progress, and the general support for these new extensions should improve, in the whole ecosystem, in the next months.

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