Model rendering lost some details

When use Cesium Sandcastle to test my glb file, it lost many details. Any idea about this?
Watercraft.ArleighBurke.glb (277.5 KB)

I see the glTF does not have normals, can you export in obj2gltf with normals and try again?

Thanks for your reply. I used obj2glf to convert my objfile to this glb file. Sorry i can’t upload the obj file.I’m using windows 11.But i can see the entire thing with all details on

It might be that the OBJ file does not contain normals. You can check this when you open the OBJ file with a text editor: If there are no lines that start with vn, then there are no normals. If this is the case, then the resulting glTF file will also not have normals.

When a glTF file does not contain normals, then the viewer should compute “flat” normals automatically. But CesiumJS currently does not automatically compute thes normals. This is tracked in issue 6506.

One approach for resolving this could be to use any tool or viewer to compute the flat normals, and then export the glTF file with these normals.

Thank you very much for your reply.