Automation of Height Transformation in Cesium ion

To the best of my knowledge, any pre-defined coordinate system will be automatically transferred to the WGS84 coordinate system in Cesium ion.

When I upload the raster terrain, the height datum in Hong Kong Principal Datum (HKPD) can successfully be transformed to ellipsoidal height. However, if I choose the data as 3D tiles, the height datum remains local. Therefore, I wonder why the height datum in 3D tiles cannot be changed automatically? Is it because of lacking the transformation matrix definition of height datum in the .json file?

Thank you.

Hi

Can you share some more information about the data source you are using when choosing 3D Tiles as output?

For background, the terrain and 3D Tiles run through different pipelines. Since data source like OBJs etc don’t inherently include CRS definitions, its not always a 1:1 match in terms of transformation, and the pipelines do the best available transformation.

Once you share how you are uploading data for the 3D Tiles output, we can look into it more.

Shehzan

Hi, @Shehzan_Mohammed

The data souce is in Cesium 3D tiles format, which generated by the .ogsb format.
image
The procedure of uploading the 3d tiles in Cesium format

Hi

If you are uploading pre-tiled 3D Tilesets, then Cesium ion does not apply any transformations or additional processing on it. This would be the responsibility of the software generating the 3D Tiles to take height reference into account.

You can choose to upload OBJ, glTF, or other supported formats instead. In this case, the Cesium pipelines will run the processing, and depending on the references detected, it will either automatically place the file, or give you the option to adjust it manually.

Shehzan