Extended GeoJSON geometries
Azure Maps provides a list of powerful APIs to search inside and along geographical features. These APIs adhere to the standard GeoJSON spec of representing geographical features.
The GeoJSON spec supports only the following geometries:
- GeometryCollection
- LineString
- MultiLineString
- MultiPoint
- MultiPolygon
- Point
- Polygon
Some Azure Maps APIs accept geometries that aren't part of the GeoJSON spec. For instance, the Search Inside Geometry API accepts Circle and Polygons.
This article provides a detailed explanation on how Azure Maps extends the GeoJSON spec to represent certain geometries.
The GeoJSON spec doesn't support the Circle
geometry. The GeoJSON Point Feature
object is used to represent a circle.
A Circle
geometry represented using the GeoJSON Feature
object must contain the following coordinates and properties:
Coordinate | Property |
---|---|
Center | The circle's center is represented using a GeoJSON Point object. |
Radius | The circle's radius is represented using GeoJSON Feature 's properties. The radius value is in meters and must be of the type double . |
SubType | The circle geometry must also contain the subType property. This property must be a part of the GeoJSON Feature 's properties and its value should be Circle |
Here's how you represent a circle using a GeoJSON Feature
object. Let's center the circle at latitude: 47.639754 and longitude: -122.126986, and assign it a radius equal to 100 meters:
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [-122.126986, 47.639754]
},
"properties": {
"subType": "Circle",
"radius": 100
}
}
The GeoJSON spec doesn't support the Rectangle
geometry. The GeoJSON Polygon Feature
object is used to represent a rectangle. The rectangle extension is primarily used by the Web SDK's drawing tools module.
A Rectangle
geometry represented using the GeoJSON Polygon Feature
object must contain the following coordinates and properties:
Coordinate | Property |
---|---|
Corners | The rectangle's corners are represented using the coordinates of a GeoJSON Polygon object. There should be five coordinates, one for each corner. And, a fifth coordinate that is the same as the first coordinate, to close the polygon ring. It's assumed that these coordinates align, and that the developer may rotate them as wanted. |
SubType | The rectangle geometry must also contain the subType property. This property must be a part of the GeoJSON Feature 's properties, and its value should be Rectangle. |
{
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [[[5,25],[14,25],[14,29],[5,29],[5,25]]]
},
"properties": {
"subType": "Rectangle"
}
}
Learn more about GeoJSON data in Azure Maps:
Review the glossary of common technical terms associated with Azure Maps and location intelligence applications: