EPSG code for exporting local 3D city Tileset

I am trying to use a local 3D city as tilesets. I am using the 3D BAG dataset for Netherlands, which comes as CityJSON files in EPSG:7415; I want to display this as a local tileset layer in Cesium for unreal, however from what I have looked at so far, Cesium expects the coordinates to be in an ECEF system so I reprojected the CityJSON dataset into EPSG:4978, however, this doesn’t show up at the right location, its Z is rather shifted downwards, so the whole dataset gets displayed below terrain.

Even when I transform the dataset inside the unreal engine editor to shift the Z, the buildings are all at different heights and not clamped to the terrain.

I am using Safe FME to do all the transformations and reprojections.

Please help

Hello @pratyush1611,

I have a few questions to better help you with this issue.

  • You mentioned the tileset uses CityJSON - this tileset loaded successfully with Cesium for Unreal? Aside from the building location, are the buildings rendering as you would expect?
  • Are you using Cesium World Terrain?
  • Are the buildings all approximately the same height relative to each other, or do they seem to be aligned to some other terrain? It may help to hide the terrain in order to determine this. Any pictures you can provide would also be helpful.

Additionally, you can try reprojecting the dataset to EPSG:4979. This may have better results.

I suspect that you will need to tile the dataset with Cesium World Terrain in order to have the buildings clamp to the ground. If that is the case, you would need to upload the dataset to ion.