gltf scale factor and georeference

Hi all!

I'm testing the glTf functionalities in Cesium: i'm trying to import a 3D model of a city, converted from COLLADA to glTF using the official conversion tool brovided in the glTf branch.

The converter works well and the 3D model is visualized in Cesium with very good performances, but there are some issues:

1) scale factor: what is the scale factor that I have to use in Cesium for 3D models?
2) there is any way to georeference the glTF 3D model?

Additional information:

-the COLLADA 3D model of the city was created starting from a CityGML file and converted by FME

If someone wants some screenshot let me now...



We’re happy to see a screenshot, thanks.

glTF will have everything in meters (#23) but that is not implemented in the converter yet. I’ll followup with Fabrice (the main converter developer) about that. Right now, it will have the same units as the COLLADA file. Scale just multiples this, e.g., 2.0 is twice the size and 0.5 is half the size.

glTF will not have geolocation in the 1.0 spec. However, there will be a geolocation extension that Cesium will implement. The schema is still TBA, but it will be simple longitude, latitude, and height like COLLADA. In the meantime, you can reference a glTF asset from a CZML file to define its location. Here’s an example CZML file.


Hi Patrick

Here the screenshot of the glTF model created by the use of a cityGML-LOD2 (with roofs) of an Italian city

Hope to hear news about the geolocation :slight_smile:

Cool. Thanks for sharing. How many buildings is that?


The entire city is composed by (more or less) 10k buildings

the performances are incredible good!!!

Great - thanks for the info!