@yuan1405
Now I know How add metadata to glTF 
. Here is topic with working example:
Here is example with metadata:
https://github.com/CesiumGS/cesium-unreal/files/12613418/TestStructuralMetadata.zip
If you want make own metadata. You need add attributes _FEATURE_ID_0 tabel in Blender:
than connect this table to vertex:
and export model with attributes like glTF:
Then make file.bin with metadata for example:
Red are height, yellow is elementID
FLOAT32 big-endian hexa 0x00002041 = 10
FLOAT32 big-endian hexa 0x0000F041 = 30
FLOAT32 big-endian hexa 0x00004842 = 50
elemetID:
INT32 hexa 0x00000000 = 0
INT32 hexa 0x01000000 = 1
INT32 hexa 0x02000000 = 2
Here is my example with blender 
budynki.zip (217.5 KB)
This zip example is in Warsaw Poland:
I change teksture when metadata is 30:
