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How To: Get latitude and longitude coordinates from a projected point shapefile

Summary

This article contains an example that shows how to get latitude and longitude coordinate values for point shapefiles that use a projected coordinate system.

Procedure

This example assumes the point shapefile was generated by digitizing over a projected USGS TIFF quad. The projection of the point shapefile is assumed to be the same as the TIFF image. You must know the projection of the image, which may be different than the one in the example.

Steps 5 and 6 show how to add a shapefile in the Geographic Coordinate System to a view that contains a projected image. These steps align the shapefile and the image.

  1. Load the existing project containing the USGS quad and point shapefile.
  2. Un-project the point shapefile into the Geographic Coordinate System (Decimal Degrees).
    See: How To: Unproject shapefiles from UTM NAD 83 to GCS NAD 83 (Decimal Degrees)
  3. Load the new shapefile into a new view.
  4. Get X and Y coordinates for the new shapefile.
    See: How To: Get X and Y coordinates for a point or a polygon centroid
    The addxycoo.ave sample script returns the latitude and longitude coordinates.
  5. Load the USGS quad into the view.
  6. Set the projection of the view to the projection of the USGS quad.
    See: How To: Set a view's map units and projection