STAR*NET V6 - Circe

Option Group: Units
Chapter 4 Options
Select both linear and angular units for your project. Select linear units from the
dropdown selection list, and angular units from the DMS or GONS radio buttons.
Adjustment results are always published using the selected units. By default, your input
data is assumed to be entered in these units.
An inline “.UNITS” option, however, may be used in your data to allow entry of
measurements in other units. Measurements entered in these alternate units are
automatically converted to the units set for the project during the run.
Option Group: Coordinate System
Select the coordinate system used in the adjustment.
When you select “Local,” your input and output coordinates are based on some local
scheme. The method used to scale your input distance observations to produce the
desired local coordinates is set in the “Local Jobs - Default Datum Scheme” adjustment
options described later in this section.
When you select “Grid,” your input and output coordinates are based on some defined
grid system. Published geodetic calculations are rigorously employed in the adjustment
process to produce properly calculated grid coordinates and geodetic positions. You can
choose from several grid systems: NAD27, NAD83, UTM and Custom:
Once you select a grid system, you can then select a specific zone from a dropdown list.
The zone list selection dialogs for NAD27, NAD83, UTM and Custom grid systems, the
definition of Custom Zones, and special input issues for grid projects are discussed in
detail in Chapter 10, “Adjustments in Grid Coordinate Systems.”
Option Group: 2D Jobs
When an adjustment is 2D, an average project elevation should always be entered so that
certain data reduction calculations (i.e. slope reduction of 3D observations to horizontal)
can be accurately performed using curved earth-geometry for both local and grid jobs. In
addition, when adjusting a local job, and you wish to have data reduced to a common
datum as described in the next option group, an average project elevation must be
known. Likewise, for a grid job, an average project elevation must also be available to
calculate proper grid factors. For some additional elevation-related issues for 2D jobs,
see “Entering Reference Elevations in 2D Projects” in Chapter 5, “Preparing Data.”
An inline “.PELEVATION” option may be entered in data files to redefine the default
project elevation for various parts of a 2D project when you feel it is necessary.
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