Transform b3dm models to 'world space'

We are working with the glb format using the 3d tiled model. We are using the format b3dm, and we are transforming the coordinates to another projection (Sweref99). In this process, we need to be able to align the model to the world x,y,z space (1,0,0)(0,1,0)(0,0,1), but the resulting data is aligned to the ECEF position (as I understand it). We already perform this transformation action for pnts-data, which does not adhere to this alignment.

After searching around the internet, I still don’t understand what process I need to perform to rotate the finalized model to ‘world space’. This is most likely a lack of understanding of what is the term for the projection of the source data, target projection/state.

We already compensate for y-up, but from there we do not know where to go.

What is the rotation the b3dm model adhere to that tangents the earth position? What is the term?
What is the term for the “world space” state that we desire to reach?
What is the process / algorithm that is needed to rotate the model correctly?

I hope I made my case clear enough for someone to understand :slight_smile:

I’m not sure there are many B3DM users here – you may have better luck asking on a Cesium forum or GitHub issue.