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A map projection is an attempt to portray the curved surface of the earth on a flat piece of paper or computer screen. Map projections have two parts: the reference datum and the coordinate system.
The reference datum is a model of zero elevation, which is used to calculate latitude and longitude for a point on the Earths surface (see the Datum tab help screen). The coordinate system essentially is a set of coordinates that transforms latitude and longitude on a globe into XYs on a flat map (see the Standard or Custom coordinate system tab help screen).
To view and change a Petra projects map projection, in the Main Module select Project>Settings>Set Map Projection
or select the
 button on the Project tab.
Details tab
Custom (Coordinate System) tab
Standard (Coordinate System) tab
Datum tab
Units tab
Quadrant tab
Map Rotation tab
Convert Crds tab
Lock/Unlock tab
Advanced tab
File tab
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