STAR*NET V6 - Circe

Chapter 10 Adjustments in Grid Coordinate Systems
10.8 Selecting a Custom Zone
Custom zones are coordinate system zones individually defined by the user. They may be
zones defining specific international locations (for example, the Great Britain national
grid, Ireland grid, Singapore grid, etc.) or special township or county coordinate system
grids now being commonly implemented in the United States. Users might even wish to
set up special grid system for a particular project.
To select a custom zone, choose Custom from the Grid selection dropdown selection list
previously shown and the zone selection dialog will automatically appear. Or if Custom
is already selected, simply press the large zone list button to select a new zone.
To select a particular zone, either type the zone name in the “Zone” field, or use your
mouse to scroll through the selection list and click on a zone to highlight it. Press the
“Show Parameters” button if you wish to see the zone’s projection and its parameters.
Press OK to actually choose the zone and exit the dialog. Or simply double-click the
zone from the selection list to choose it and exit the dialog in one step.
Parameters for custom coordinate system zones are stored in a standard text file named
STAR6.CUS located in the same directory you installed STAR*NET. This file comes
with a few custom zones already entered for illustration. Since this file is a standard text
file, you can view and modify its contents using any text editor. Besides the custom
coordinate system zone definitions, this file also contains ellipsoid definitions and
custom linear units definitions.
The ability to edit custom coordinate system zone data into the STAR6.CUS file is a very
important feature in the STAR*NET package. The contents of the file, and the format of
custom information is described in detail later in this chapter.
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