空间数据格式(地理数据格式)：GeoJSON(FeatureCollection)与EsriJSON(FeatureSet/ArcGIS格式)

一、FeatureCollection(GeoJSON)格式介绍

https://learn.microsoft.com/en-us/javascript/api/azure-maps-control/atlas.data.featurecollection?view=azure-maps-typescript-latest

1、FeatureCollection格式

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{   type: "FeatureCollection",   features: [{     type: "Feature",     geometry: geometry,     properties: {}   }] }

 2、 Geometry格式

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{     type: "Point | MultiPoint | LineString | MultiLineString | Polygon | MultiPolygon",     coordinates: 数组 }

3、Point数组 ，也是下文的position数组

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1 2	[longitude, latitude, elevation]. position: [longitude, latitude, elevation]

4、MultiPoint数组

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1	coordinates:position[]

5、LineString数组

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1	coordinates:position[]

6、MultiLineString数组

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1	coordinates:position[][]

7、Polygon数组

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1	coordinates:Position[][]

8、MultiPolygon数组　

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1	coordinates:position[][][]

二、FeatureSet，EsriJSON格式介绍

1、FeatureSet格式

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{     "objectIdFieldName": "objectid",     "globalIdFieldName": "globalid",     "geometryType": "esriGeometryPoint | esriGeometryMultipoint | esriGeometryPolyline | esriGeometryPolygon | esriGeometryEnvelope",     "spatialReference": {         "wkid": 102100,         "latestWkid": 3857     },     "fields": [{         "name": "objectid",         "alias": "OBJECTID",         "type": "esriFieldTypeOID"     }],     "features": [{         "geometry": {},         "attributes": {}     }] }

2、Point类型的geometry

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A 2D point geometry:{   "x": -118.15,   "y": 33.80,   "spatialReference": {     "wkid": 4326   } }

3、MultiPoint类型的Geometry

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A 2D multipoint geometry:{   "points": [     [       -97.06138,       32.837     ],     [       -97.06133,       32.836     ]   ],   "spatialReference": {     "wkid": 4326   } }

4、Polyline类型的Geometry

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2D polylines geometry:{   "paths": [     [       [-97.06138,32.837],       [-97.06133,32.836],       [-97.06124,32.834],       [-97.06127,32.832]     ],     [       [-97.06326,32.759],       [-97.06298,32.755]     ]   ],   "spatialReference": {"wkid": 4326} }

5、PolyGon类型的Geometry

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A 2D polygon geometry:{   "rings": [     [       [-97.06138,32.837],       [-97.06133,32.836],       [-97.06124,32.834],       [-97.06127,32.832],       [-97.06138,32.837]     ],     [       [-97.06326,32.759],       [-97.06298,32.755],       [-97.06153,32.749],       [-97.06326,32.759]     ]   ],   "spatialReference": {     "wkid": 4326   } }

三、GeoJSON和EsriJSON的异同点

1、属性信息的异同点

geojson没有关于属性元数据的描述，fields数组、displayfield字段等；相同点是都在feature内部记录，geojson的属性字段为properties,esrijson的属性字段为attruibutes

2、坐标信息的异同点

geojson的坐标信息由不同维度的数组表示，由coordinates属性表示，每个geometry用type属性来区分是什么类型的几何；esrijson的单点是用x/y属性记录，其余多点、线、面用二维和三维数组记录，区分不同类型的几何体取决于geometry对象内的属性字段，分别为points,paths,rings。esrijson没有multipolygon和multipolyline。相同点是，二者多点和面的数组维度是一致的。