Selecting a Coordinate System

To select a coordinate system:

1. By default, the Calculator starts with the geodetic coordinate system of WGS84 selected, or it will automatically recognize the coordinate system from specified input data.

   See General Preferences to modify the default coordinate system.

   To select a system, double-click on the blue box labeled System in a Coordinate System area.  
   
   

   Right-clicking on the blue System box also provides quick options for Select Coordinate System, Select Coordinate System by Map or choose Info to see details about the current system.

   

2. If this is the first time you have selected a coordinate system, you will be asked if you would like to limit the coordinate systems by geographic area. This option will provide a map display that can be used to build a location filter of the available coordinate systems.

   Select no to browse or perform a text search on the full datasourceThe database of geodetic parameters. This includes objects like Coordinate Systems, Datums, Coordinate Transformations, Units of Measure, etc. The Geographic Calculator includes both a built-in default datasource, and a custom datasource, which contains edits and additions made by the user or administrator. of coordinate systems by folders.

   Select yes to filter the coordinate systems by location selected on the map.

   If you would like to be asked this each time, check the Always Prompt option. If you want your choice to be saved for all future system selections uncheck this box. This setting can be modified in your preferences at a later date, as needed.
   
   

3. Selecting Yes will open the Coordinate System Selection window. If you do not know the precise name of the coordinate system you are looking for and would like to browse the available coordinate systems for a specific area, you can define a point or an area on this window using the Select Coordinate System By Rectangle tool or the  Select Coordinate System by Point tools found on the Coordinate System Selection window's toolbar. The Y and X values for the cursor location (Latitude, Longitude) will display in the bottom of the dialog.

   
   

   Selecting a coordinate system by rectangle will result in a list of coordinate systems that contain the boundaries of the polygon defined with the Select Coordinate System By Rectangle tool. Press and drag on the map to create a rectangle, then release to complete the rectangle.

   Selecting a coordinate system by point will result in a list of coordinate systems that overlap with the point generated using the Select Coordinate System by Point tool.  Left-click on the map to place a point. Left-click again to move the point to a new location.

   You may also use the Select Coordinate System By GeoCalc Polygon tool to import a polygon Area of UseAn area of use is a polygon that defines the applicable extent of an object in the datasource, such as a coordinate reference system or transformation.They are defined as both a polygon and a minimum bounding rectangle in Latitude / Longitude coordinates in WGS84. from an object defined in the DatasourceThe database of geodetic parameters. This includes objects like Coordinate Systems, Datums, Coordinate Transformations, Units of Measure, etc. The Geographic Calculator includes both a built-in default datasource, and a custom datasource, which contains edits and additions made by the user or administrator.. Clicking this tool will bring up a Select Area of Use from GeoCalc Datasource Object dialog.
   

   

   From this dialog, you may select one of several types of objects, including specific Areas of Use, or Concatenated Transforms, Single Transforms, or Coordinate Systems that have associated Areas of Use. Once you have selected a particular object and click OK, the Area of Use associated with that object will be imported into the Viewer and displayed atop the world map, to be applied as the limiting polygon.  

   Example
   

   In this example the Areas of Use folder is selected and searched for North Sea (by entering in the Find field at the bottom of the dialog).

   

   After selecting the appropriate Area of Use, the polygon displays on the map:

   

   After confirming the polygon by clicking OK, the available Coordinate systems are filtered to only those that can be applied to every location in the North Sea.

   

   If you select OK after defining your selection or you choose No in step 2 the Select Coordinate System from Datasource dialog will open.

4. In the Select Coordinate System dialog, coordinate systems are organized in the folder list on the left by type (Geodetic (Lat/Lon), Projected, GeocentricA geocentric coordinate system is a 3-dimensional coordinate system represented by X,Y,Z coordinates. The origin of the system is the center of the earth.This is also refered to as earth-centered, earth-fixed (ECEF)., FittedA local survey grid or engineering system paired with a polynomial transformation to relate the system to a known geodetic or projected system. The transformation may be calculated by minimizing the error for a set of control points that define coordinates in both the local system and a known system., and StringA grid coordinate system where the coordinates are represented as an alpha-numeric string.), continent, then by country and smaller political sub-units.  If a coordinate system covers an entire continent, it will be found by clicking on the continent folder itself.  Universal Transverse Mercator (UTM) systems are given their own top level groups.  If you are unable to find your desired coordinate system, try using the search field at the bottom of the window. Once you have found and selected your desired coordinate system, click OK to return to the Job page.

5. Right click on the blue System box that lists the coordinate system to see additional options, including Copy, Paste or Swap source and target systems. There are also options to Export to File (*.prj, *.wkt, *.wkt2, *.gml) or View PRJ to see the WKT definition.

   

6. To use a Horizontal Time Dependent Positioning (HTDP) transformation, select the appropriate date for your data. Time-dependent transformations can be enabled or disabled in the General Preferences

7. To include vertical (height) data, double-click the Vertical box to select a vertical reference system.

8. Repeat this process to select the target coordinate system for the job, if applicable.