My purpose is to export a 3D object from Blender (2.81) with the integrated glTF Exporter which shows just a geological surface layer. The data contain a tin with the location values and were imported with the help of BlenderGIS plugin. The result will be displayed in a Cesium based globe view. The point is, the import data contain also additional information like uncertainty value and an ID for each triangle. The import of these additional information is another topic, but is it generally possible to export additional information of the triangles from Blender into the a glb file? Or is all information other than the topology and material lost during the export? The point is that this additional information should be retrievable at the layer in Cesium viewer. The most appropriate way seems to me to store the information in the glb and the respective coordinate.
I don’t know.
You could try to add a color-attribute or texture-coordinates to the model and store per vertex data there.
glTF supports custom vertex attributes. So the data wouldn’t be per-triangle, but per-vertex data is what the engine is likely to need anyway. Currently, you’d need to export that from Blender using an additional vertex color or UV map layer, as @CarstenT suggests. We’re looking at other ways to support it using weight painting, too, see https://github.com/KhronosGroup/glTF-Blender-IO/pull/807.
I’m not familiar enough with Cesium to say which of these options are compatible there. I expect it would at least load the data, but you’d have to figure out how to access it for display.