OGR python projection

OGR Projection



If you're using shapely and you need to do projections, you'll either have a lot of boilerplate or a function like this one. Actually, even in OGR, there's a lot of bioler plate involved in transforming....



from osgeo import ogr
from shapely.wkb import loads

def project(geom, to_epsg=900913, from_epsg=4326):
    """utility function to do quick projection with ogr,
    to and from shapely objects
    >>> from shapely.geometry import LineString
    >>> l = LineString([[-121, 43], [-122, 42]])
    >>> lp = project(l, from_epsg=4326, to_epsg=26910)
    >>> lp.wkt
    'LINESTRING (663019.0700828594854102 4762755.6415722491219640, 582818.0692490270594135 4650259.8474613213911653)'
    """

    to_srs = ogr.osr.SpatialReference()
    to_srs.ImportFromEPSG(to_epsg)

    from_srs = ogr.osr.SpatialReference()
    from_srs.ImportFromEPSG(from_epsg)

    ogr_geom = ogr.CreateGeometryFromWkb(geom.wkb)
    ogr_geom.AssignSpatialReference(from_srs)

    ogr_geom.TransformTo(to_srs)
    return loads(ogr_geom.ExportToWkb())

import doctest
doctest.testmod()

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