X,Y to Longitude,Latitude

Use the Gravity > Locations > X,Y -> Longitude,Latitude menu option (GRXY2LL GX) to convert X,Y coordinates from a projected or local coordinate system to longitude and latitude coordinates.

X,Y -> Longitude,Latitude dialog options

Conversion method

Choose the conversion method:

  • Select Projected coordinate system to use a map projection.

    The New Projected Coordinate System dialog opens.

  • Select Local coordinate system to use a reference location and orientation (origin and azimuth).

    The Create Longitude, Latitude from Local (X,Y) dialog opens (see below).

Script Parameter: GRXY2LL.METHOD

Create Longitude, Latitude from Local X,Y dialog options

Local X

The local X coordinate of the reference geographic location.

Script Parameter: LL2XY.LOCX

Local Y

The local Y coordinate of the reference geographic location.

Script Parameter: LL2XY.LOCY

Local length units

The units of the local coordinate system, selected from POSC-compatible abbreviations (for example, “m” or “ft”).

Script Parameter: LL2XY.UNITS

Local grid Y direction (deg azimuth)

The azimuth of the local Y-axis, measured clockwise from geographic North.

Script Parameter: LL2XY.AZM

Longitude of local (X,Y)

The longitude of the geographic reference location associated with the defined local (X,Y) origin.

Script Parameter: LL2XY.LOCLON

Latitude of local (X,Y)

The latitude of the geographic reference location associated with the defined local (X,Y) origin.

Script Parameter: LL2XY.LOCLAT

Application Notes

This procedure is useful if you have data points with known local X,Y coordinates defined using a reference location and orientation, and you want to convert them to longitude and latitude coordinates.

  • Projected coordinate system: For the projected method, the X,Y coordinates are converted to longitude and latitude using the selected projected coordinate system.

  • Local coordinate system: For the local method, the local X,Y coordinates are first rotated according to the specified Y-axis azimuth, then converted to longitude and latitude using the inverse Transverse Mercator projection centered on the reference location.

A local coordinate system is an arbitrary Cartesian coordinate system defined and oriented for the purposes of a particular study.

See Also: