PROJJSON¶

+

PROJJSON is a JSON encoding of +WKT2:2019 / ISO-19162:2019, +which itself implements the model of +OGC Topic 2: Referencing by coordinates. +Apart from the difference of encodings, the semantics is intended to be exactly +the same as WKT2:2019.

+

PROJJSON is available as input and output of PROJ since PROJ 6.2.

+

The current version is 0.4.

+

Schema¶

+

A JSON schema of its grammar is available at +https://proj.org/schemas/v0.4/projjson.schema.json

+

History¶

+

v0.4: additional properties allowed in id object (version, authority_citation, uri)
v0.3: additional properties allowed in BoundCRS object (name, scope, area, bbox, usages, remarks, id, ids)
v0.2: addition of geoid_model in VerticalCRS object.
v0.1: initial version for PROJ 6.2

+

Content¶

+

The high level objects are:

+

Coordinate Reference Systems (CRS):
+
- Common ones:
  +
  - GeographicCRS
  - GeodeticCRS
  - ProjectedCRS
  - CompoundCRS
  - BoundCRS
  +
- More esoteric ones:
  +
  - VerticalCRS
  - EngineeringCRS
  - TemporalCRS
  - ParametricCRS
  - DerivedGeographicCRS
  - DerivedGeodeticCRS
  - DerivedProjectedCRS
  - DerivedVerticalCRS
  - DerivedEngineeringCRS
  - DerivedTemporalCRS
  - DerivedParametricCRS
  +
+
Coordinate operations:
+
- Transformation
- Conversion
- ConcatenatedOperation
+
Others:
+
- PrimeMeridian
- Ellipsoid
- Datum
- DatumEnsemble
+

+

Examples¶

+

GeographicCRS¶

+

The following invocation

+

projinfo EPSG:4326 -o PROJJSON -q
+

+

+

will output:

+

{
+    "$schema": "https://proj.org/schemas/v0.1/projjson.schema.json",
+    "type": "GeographicCRS",
+    "name": "WGS 84",
+    "datum": {
+        "type": "GeodeticReferenceFrame",
+        "name": "World Geodetic System 1984",
+        "ellipsoid": {
+            "name": "WGS 84",
+            "semi_major_axis": 6378137,
+            "inverse_flattening": 298.257223563
+        }
+    },
+    "coordinate_system": {
+        "subtype": "ellipsoidal",
+        "axis": [
+        {
+            "name": "Geodetic latitude",
+            "abbreviation": "Lat",
+            "direction": "north",
+            "unit": "degree"
+        },
+        {
+            "name": "Geodetic longitude",
+            "abbreviation": "Lon",
+            "direction": "east",
+            "unit": "degree"
+        }
+        ]
+    },
+    "area": "World",
+    "bbox": {
+        "south_latitude": -90,
+        "west_longitude": -180,
+        "north_latitude": 90,
+        "east_longitude": 180
+    },
+    "id": {
+        "authority": "EPSG",
+        "code": 4326
+    }
+}
+

+

+

ProjectedCRS¶

+

The following invocation

+

projinfo EPSG:32631 -o PROJJSON -q
+

+

+

will output:

+

{
+    "$schema": "https://proj.org/schemas/v0.1/projjson.schema.json",
+    "type": "ProjectedCRS",
+    "name": "WGS 84 / UTM zone 31N",
+    "base_crs": {
+        "name": "WGS 84",
+        "datum": {
+            "type": "GeodeticReferenceFrame",
+            "name": "World Geodetic System 1984",
+            "ellipsoid": {
+                "name": "WGS 84",
+                "semi_major_axis": 6378137,
+                "inverse_flattening": 298.257223563
+            }
+        },
+        "coordinate_system": {
+            "subtype": "ellipsoidal",
+            "axis": [
+            {
+                "name": "Geodetic latitude",
+                "abbreviation": "Lat",
+                "direction": "north",
+                "unit": "degree"
+            },
+            {
+                "name": "Geodetic longitude",
+                "abbreviation": "Lon",
+                "direction": "east",
+                "unit": "degree"
+            }
+            ]
+        },
+        "id": {
+            "authority": "EPSG",
+            "code": 4326
+        }
+    },
+    "conversion": {
+        "name": "UTM zone 31N",
+        "method": {
+            "name": "Transverse Mercator",
+            "id": {
+                "authority": "EPSG",
+                "code": 9807
+            }
+        },
+        "parameters": [
+        {
+            "name": "Latitude of natural origin",
+            "value": 0,
+            "unit": "degree",
+            "id": {
+            "authority": "EPSG",
+            "code": 8801
+            }
+        },
+        {
+            "name": "Longitude of natural origin",
+            "value": 3,
+            "unit": "degree",
+            "id": {
+            "authority": "EPSG",
+            "code": 8802
+            }
+        },
+        {
+            "name": "Scale factor at natural origin",
+            "value": 0.9996,
+            "unit": "unity",
+            "id": {
+            "authority": "EPSG",
+            "code": 8805
+            }
+        },
+        {
+            "name": "False easting",
+            "value": 500000,
+            "unit": "metre",
+            "id": {
+            "authority": "EPSG",
+            "code": 8806
+            }
+        },
+        {
+            "name": "False northing",
+            "value": 0,
+            "unit": "metre",
+            "id": {
+            "authority": "EPSG",
+            "code": 8807
+            }
+        }
+        ]
+    },
+    "coordinate_system": {
+        "subtype": "Cartesian",
+        "axis": [
+        {
+            "name": "Easting",
+            "abbreviation": "E",
+            "direction": "east",
+            "unit": "metre"
+        },
+        {
+            "name": "Northing",
+            "abbreviation": "N",
+            "direction": "north",
+            "unit": "metre"
+        }
+        ]
+    },
+    "area": "World - N hemisphere - 0°E to 6°E - by country",
+    "bbox": {
+        "south_latitude": 0,
+        "west_longitude": 0,
+        "north_latitude": 84,
+        "east_longitude": 6
+    },
+    "id": {
+        "authority": "EPSG",
+        "code": 32631
+    }
+}
+

+

+

+ + +

+