3D model doesn't have correct rotation after converted vertices into ECEF

Hi Team,

I’m having issue on reprojecting the vertices following this Support tiling georeferenced 3D models into 3D Tiles - #3 by omar

this is the python function(using pyproj) that I use for re-projection from epsg 6677 to epsg 4978(which is ecef on wgs84).

def _convert_proj2ecef(self, proj_xyz):
    crs_proj = CRS.from_epsg(self.epsg) 
    crs_4978 = CRS.from_epsg(4978)
    transformer = Transformer.from_crs(crs_proj, crs_4978)
    return transformer.transform(proj_xyz[0], proj_xyz[1], proj_xyz[2])

However, the model will be tilted like this, which should be overlaid to point cloud.

Any idea what is wrong?