I am trying to find the area of some geometries in France using ogr2ogr
. The spread of these geometries span multiple UTM zones (see Réunion, Guyane).
I have seen get_GeodesicArea
, which seems to do exactly what I need:
Get the area of the (closed) curve, considered as a surface on the
underlying ellipsoid of the SRS attached to the geometry.
It also says:
Note that geometries with circular arcs will be linearized in their
original coordinate space first, so the resulting geodesic area will
be an approximation.
This is ok for my usecase.
I have also found a reference to OGR2SQLITE_ST_GeodesicArea
.
Reproducible setup
Here is franceTest.geojson
:
{
"type": "FeatureCollection",
"name": "franceTest",
"crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } },
"features": [
{ "type": "Feature", "properties": { }, "geometry": { "type": "Polygon", "coordinates": [ [ [ -53.27917836, 4.34657742 ], [ -53.65825646, 3.86953154 ], [ -52.93198534, 3.29672455 ], [ -53.27917836, 4.34657742 ] ] ] } },
{ "type": "Feature", "properties": { }, "geometry": { "type": "Polygon", "coordinates": [ [ [ 55.52739964, -21.00728513 ], [ 55.44252555, -21.09369598 ], [ 55.65702552, -21.13256448 ], [ 55.52739964, -21.00728513 ] ] ] } }
]
}
Attempts
I tried the following:
ogr2ogr franceOut.geojson franceTest.geojson -sql "SELECT ST_GeodesicArea(geometry) as area FROM franceTest"
Output:
ERROR 1: Undefined function 'ST_GeodesicArea' used.
Then I tried to use SQLite:
ogr2ogr franceOut.geojson franceTest.geojson -dialect SQLite -sql "SELECT ST_GeodesicArea(geometry) as area FROM franceTest"
Output:
ERROR 1: In ExecuteSQL(): sqlite3_prepare_v2(SELECT ST_GeodesicArea(geometry) as area FROM franceTest): no such function: ST_GeodesicArea
Then I tried to use OGR SQL dialect:
ogr2ogr franceOut.geojson franceTest.geojson -dialect OGRSQL -sql "SELECT ST_GeodesicArea(geometry) as area FROM franceTest"
Output:
ERROR 1: Undefined function 'ST_GeodesicArea' used.
Then I tried, without having any good reason:
ogr2ogr franceOut.geojson franceTest.geojson -sql "SELECT GeodesicArea(geometry) as area FROM franceTest"
Output:
ERROR 1: Undefined function 'GeodesicArea' used.
How can I call get_GeodesicArea
, or equivalent function using ogr2ogr
?