How do you find the geographic size in meters given a lower left coordinate and upper right coordinate. The projection would be WGS84 projection. Ex. 33,-119,35,-117. What would be the area in meters that covers?

  • The answer depends on the units -- I assume you are giving latitude/longitude in degrees here? – Erica Aug 4 '14 at 13:28
  • Yes WGS84 is correct. – inspiration Aug 4 '14 at 13:28
  • The answer will also depend on what Projected Coordinate System you choose to project into. Would you be able to edit your question to specify that, please? – PolyGeo Aug 4 '14 at 13:31

So, with ArcMap, from ESRI Forums:

Private Function PolygonFromEnvelope(pEnv As IEnvelope) As IPolygon

Dim pPtColl As IPointCollection

Set pPtColl = New Polygon
With pPtColl
    .AddPoint pEnv.LowerLeft
    .AddPoint pEnv.UpperLeft
    .AddPoint pEnv.UpperRight
    .AddPoint pEnv.LowerRight
    'Close the polygon
    .AddPoint pEnv.LowerLeft
End With
Set PolygonFromEnvelope = pPtColl

End Function

then Measure Area (ArcMAP 10.2)

or maybe using GDAL/OGR:

from osgeo import ogr

    def my_envelope(geom):
       (minX, maxX, minY, maxY) = geom.GetEnvelope()

        # Create ring
        ring = ogr.Geometry(ogr.wkbLinearRing)
        ring.AddPoint(minX, minY)
        ring.AddPoint(maxX, minY)
        ring.AddPoint(maxX, maxY)
        ring.AddPoint(minX, maxY)
        ring.AddPoint(minX, minY)

        # Create polygon
        poly_envelope = ogr.Geometry(ogr.wkbPolygon)
        return poly_envelope

then calculate the polygon area (QGIS) or OGR get_area() although I'm not well-versed on GDAL/OGR so I'm not sure how it takes into account the coordinate system. QGIS should calculate with the projection in mind.

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