Long,Lat to Local X,Y

Use the Coordinates > Georeferencing > Long,Lat -> Local X,Y menu option (LL2XY GX) to convert longitude and latitude coordinates to local X,Y coordinates using a defined reference location and orientation in a local coordinate system.

The GX uses two dialogs:

  • The first dialog allows you to select the input and output channels.

  • The second dialog defines the conversion parameters.

Long,Lat -> Local X,Y dialog options

Longitude channel

The name of the input longitude channel.

Script Parameter: LL2XY.LON

Latitude channel

The name of the input latitude channel.

Script Parameter: LL2XY.LAT

Local X channel

The name of the output local X channel.

Script Parameter: LL2XY.X

Local Y channel

The name of the output local Y channel.

Script Parameter: LL2XY.Y

Convert (Longitude, Latitude) to Local (X,Y) dialog options

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

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

Application Notes

This procedure is useful if you have data points with known longitude and latitude coordinates, and you want to work in a local X,Y coordinate system.

The X,Y coordinates are calculated by projecting the longitude/latitude coordinates using a Transverse Mercator projection centered on the specified reference location (defined by the local X,Y coordinates), then rotating the result to the specified Y-axis azimuth.

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

See Also: