When I convert my 3d model to GLTF format, it hovers like in the picture. However, when I convert the same model to USDZ format, there is no problem. I adjusted the pivots of the model, it did not improve. I combined the objects again, it did not improve. I wonder where am I going wrong.
The way to fix this depends on how you are creating the original model, and what tools you are using to convert it to glTF. If you import the model in Blender, is it positioned on the ground plane? If not, you can move it there and re-export.
Alternatively, you could try using the gltf-transform CLI to move it to the ground:
gltf-transform center input.glb output.glb --pivot below
If I understand right, you’re saying the glTF model appears in the right place in both 3DS Max and Unity? If so, what is the software in which it isn’t in the right place? You may need to file a bug there.