v3.1.2将示例的osgb转成3dtiles后，3dtiles是不可见的

[muyan520]

v3.1.2将实例的osgb转成3dtiles后，3dtiles是不可见的

根节点的tileset.json内没记录任何children
{
"asset": {
"generagetool": "Cesium3DTilesConverter([email protected])",
"version": "1.0"
},
"geometricError": 1.1787726265933931e39,
"root": {
"boundingVolume": {
"box": [
0,
0,
0,
-3.4028234663852887e38,
0,
0,
0,
-3.4028234663852887e38,
0,
0,
0,
-3.4028234663852887e38
]
},
"geometricError": 1.1787726265933931e39,
"refine": "REPLACE",
"transform": [
-0.9178899270922155,
-0.39683508129026026,
0,
0,
0.15191776981696046,
-0.3513897768511734,
0.9238215281851381,
0,
-0.36660479123504166,
0.8479664751520754,
0.3828234371896219,
0,
-2339412.4892631995,
5411122.303569182,
2426554.659568095,
1
]
}
}