CityEngine导出spk并发布为Scene Layer，fields属性为空，如何处理？

CityEngine导入shp文件，然后导出spk并发布为Scene Layer，但查看SceneServer服务中fields属性为空，CE如何才能导出fields信息？服务描述信息如下：
{ "id": 0, "version": "ec331d29-a48e-439f-932a-96fbf0c4779b", "layerType": "3DObject", "spatialReference": { "wkid": 4326, "latestWkid": 4326 }, "alias": "", "description": "", "copyrightText": "", "capabilities": [ "View" ], "store": { "id": "d02ae6bf-c373-4d17-ba43-41870e873be5", "profile": "meshpyramids", "resourcePattern": [ "3dNodeIndexDocument", "SharedResource", "Geometry", "Texture" ], "rootNode": "./nodes/root", "version": "1.4", "extent": [ 116.34829207715718, 39.920321267856714, 116.35139330813666, 39.92197895882963 ], "indexCRS": "http://www.opengis.net/def/crs/EPSG/0/4326", "vertexCRS": "http://www.opengis.net/def/crs/EPSG/0/4326", "textureEncoding": [ "image/jpeg", "image/png" ], "lodType": "MeshPyramid", "lodModel": "node-switching", "defaultGeometrySchema": { "header": [ { "property": "vertexCount", "type": "UInt32" }, { "property": "faceCount", "type": "UInt32" } ], "topology": "PerAttributeArray", "ordering": [ "position", "uv0", "region", "color" ], "vertexAttributes": { "position": { "valueType": "Float32", "valuesPerElement": 3 }, "uv0": { "valueType": "Float32", "valuesPerElement": 2 }, "region": { "valueType": "UInt16", "valuesPerElement": 4 }, "color": { "valueType": "UInt8", "valuesPerElement": 4 } } } }, "fields": , "name": "test_buildings" }