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Use PROJJSON instead of WKT2:2019 #96

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May 25, 2022
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Use PROJJSON instead of WKT2:2019 #96

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beddd6e
Use PROJJSON instead of WKT2:2019
brendan-ward May 11, 2022
f06d217
Add suggestions for inferring OGC:CRS84
brendan-ward May 11, 2022
e7aa911
PR feedback
brendan-ward May 11, 2022
6156083
Use simpler OGC:CRS84 json
brendan-ward May 11, 2022
5ba901a
Feedback from #97
brendan-ward May 16, 2022
6f1a4eb
PR feedback
brendan-ward May 21, 2022
5e35112
PR feedback
brendan-ward May 24, 2022
86fb673
Merge remote-tracking branch 'upstream/main' into use_projjson
brendan-ward May 24, 2022
268acc6
Update schema and example builder script
brendan-ward May 24, 2022
6867b56
Use scripts/update_example_schemas.py
brendan-ward May 24, 2022
79eb2bc
Fix spec
brendan-ward May 24, 2022
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2 changes: 1 addition & 1 deletion examples/example.py
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Expand Up @@ -30,7 +30,7 @@
"geometry": {
"encoding": "WKB",
"geometry_type": ["Polygon", "MultiPolygon"],
"crs": df.crs.to_wkt(pyproj.enums.WktVersion.WKT2_2019_SIMPLIFIED),
"crs": json.loads(df.crs.to_json()),
"edges": "planar",
"bbox": [round(x, 4) for x in df.total_bounds],
},
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106 changes: 105 additions & 1 deletion examples/example_metadata.json
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Expand Up @@ -8,7 +8,111 @@
180.0,
83.6451
],
"crs": "GEOGCRS[\"WGS 84 (CRS84)\",ENSEMBLE[\"World Geodetic System 1984 ensemble\",MEMBER[\"World Geodetic System 1984 (Transit)\"],MEMBER[\"World Geodetic System 1984 (G730)\"],MEMBER[\"World Geodetic System 1984 (G873)\"],MEMBER[\"World Geodetic System 1984 (G1150)\"],MEMBER[\"World Geodetic System 1984 (G1674)\"],MEMBER[\"World Geodetic System 1984 (G1762)\"],MEMBER[\"World Geodetic System 1984 (G2139)\"],ELLIPSOID[\"WGS 84\",6378137,298.257223563],ENSEMBLEACCURACY[2.0]],CS[ellipsoidal,2],AXIS[\"geodetic longitude (Lon)\",east],AXIS[\"geodetic latitude (Lat)\",north],UNIT[\"degree\",0.0174532925199433],USAGE[SCOPE[\"Not known.\"],AREA[\"World.\"],BBOX[-90,-180,90,180]],ID[\"OGC\",\"CRS84\"]]",
"crs": {
"$schema": "https://proj.org/schemas/v0.4/projjson.schema.json",
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"type": "GeographicCRS",
"name": "WGS 84 (CRS84)",
"datum_ensemble": {
"name": "World Geodetic System 1984 ensemble",
"members": [
{
"name": "World Geodetic System 1984 (Transit)",
"id":
{
"authority": "EPSG",
"code": 1166
}
},
{
"name": "World Geodetic System 1984 (G730)",
"id":
{
"authority": "EPSG",
"code": 1152
}
},
{
"name": "World Geodetic System 1984 (G873)",
"id":
{
"authority": "EPSG",
"code": 1153
}
},
{
"name": "World Geodetic System 1984 (G1150)",
"id":
{
"authority": "EPSG",
"code": 1154
}
},
{
"name": "World Geodetic System 1984 (G1674)",
"id":
{
"authority": "EPSG",
"code": 1155
}
},
{
"name": "World Geodetic System 1984 (G1762)",
"id":
{
"authority": "EPSG",
"code": 1156
}
},
{
"name": "World Geodetic System 1984 (G2139)",
"id":
{
"authority": "EPSG",
"code": 1309
}
}
],
"ellipsoid": {
"name": "WGS 84",
"semi_major_axis": 6378137,
"inverse_flattening": 298.257223563
},
"accuracy": "2.0",
"id": {
"authority": "EPSG",
"code": 6326
}
},
"coordinate_system": {
"subtype": "ellipsoidal",
"axis": [
{
"name": "Geodetic longitude",
"abbreviation": "Lon",
"direction": "east",
"unit": "degree"
},
{
"name": "Geodetic latitude",
"abbreviation": "Lat",
"direction": "north",
"unit": "degree"
}
]
},
"scope": "Not known.",
"area": "World.",
"bbox": {
"south_latitude": -90,
"west_longitude": -180,
"north_latitude": 90,
"east_longitude": 180
},
"id": {
"authority": "OGC",
"code": "CRS84"
}
},
"edges": "planar",
"encoding": "WKB",
"geometry_type": [
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8 changes: 4 additions & 4 deletions format-specs/geoparquet.md
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Expand Up @@ -54,7 +54,7 @@ Each geometry column in the dataset must be included in the columns field above
| --- | --- | --- |
| encoding | string | **REQUIRED** Name of the geometry encoding format. Currently only 'WKB' is supported. |
| geometry_type | string or \[string] | **REQUIRED** The geometry type(s) of all geometries, or 'Unknown' if they are not known. |
| crs | JSON object | **OPTIONAL** [PROJJSON](https://proj.org/specifications/projjson.html) JSON object representing the Coordinate Reference System (CRS) of the geometry. If the crs field is not included then the data in this column must be stored in longitude, latitude, and CRS-aware implementations may assume a default value of [OGC:CRS84](https://www.opengis.net/def/crs/OGC/1.3/CRS84). |
| crs | JSON object | **OPTIONAL** [PROJJSON](https://proj.org/specifications/projjson.html) JSON object representing the Coordinate Reference System (CRS) of the geometry. If the crs field is not included then the data in this column must be stored in longitude, latitude based on the WGS84 datum, and CRS-aware implementations should assume a default value of [OGC:CRS84](https://www.opengis.net/def/crs/OGC/1.3/CRS84). |
| orientation | string | **OPTIONAL** Winding order of exterior ring of polygons. If present must be 'counterclockwise'; interior rings are wound in opposite order. If absent, no assertions are made regarding the winding order. |
| edges | string | **OPTIONAL** Name of the coordinate system for the edges. Must be one of 'planar' or 'spherical'. The default value is 'planar'. |
| bbox | \[number] | **OPTIONAL** Bounding Box of the geometries in the file, formatted according to [RFC 7946, section 5](https://tools.ietf.org/html/rfc7946#section-5). |
Expand All @@ -72,10 +72,10 @@ which itself implements the model of
Apart from the difference of encodings, the semantics are intended to match
WKT2:2019, and a CRS in one encoding can generally be represented in the other.

If CRS is not provided, then all coordinates in the geometry must use longitude, latitude to store their data.
If CRS is not provided, all coordinates in the geometry must use longitude, latitude
based on the WGS84 datum to store their data.

If an implementation is CRS-aware and needs a CRS representation of the data it may assume a default value is [OGC:CRS84](https://www.opengis.net/def/crs/OGC/1.3/CRS84), which is equivalent to the well-known [EPSG:4326](https://epsg.org/crs_4326/WGS-84.html) but changes the axis from latitude-longitude to longitude-latitude. However, there is no guarantee that coordinates
are represented using OGC:CRS84 versus any other geographic CRS.
If an implementation is CRS-aware and needs a CRS representation of the data it should assume a default value is [OGC:CRS84](https://www.opengis.net/def/crs/OGC/1.3/CRS84), which is equivalent to the well-known [EPSG:4326](https://epsg.org/crs_4326/WGS-84.html) but changes the axis from latitude-longitude to longitude-latitude.

Due to the large number of CRSes available and the difficulty of implementing all of them, we expect that a number of implementations will start without support for the optional `crs` field.
Users are recommended to store their data in longitude, latitude (OGC:CRS84 or not including the `crs` field) for it to work with the widest number of tools. Data that are more appropriately represented in particular projections may use an alternate coordinate reference system. We expect many tools will support alternate CRSes, but encourage users to check to ensure their chosen tool supports their chosen CRS.
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4 changes: 2 additions & 2 deletions format-specs/schema.json
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Expand Up @@ -41,8 +41,8 @@
"description": "The geometry type(s) of all geometries, or 'Unknown' if they are not known."
},
"crs": {
"type": ["string", "null"],
"description": "WKT2 representing the Coordinate Reference System (CRS) of the geometry. Can be null if the CRS is unknown."
"type": ["object", "null"],
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"description": "JSON object representing the Coordinate Reference System (CRS) of the geometry. If the crs field is not included then the data in this column must be stored in longitude, latitude based on the WGS84 datum, and CRS-aware implementations should assume a default value of OGC:CRS84."
},
"edges": {
"type": "string",
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