Instructions provided describe how to create a custom projection with a non-Greenwich central meridian and apply it to a data frame.
This article pertains to ArcGIS versions 8.x and 9.x. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.
These steps project a data frame to a custom Geographic Coordinate System with a central meridian of -180. This allows the whole Pacific Rim region of the earth to be displayed as one continuous region.
- Create a custom .PRJ file.
- In ArcCatalog, select Coordinate Systems > Geographic Coordinate Systems > World, and select the GCS_WGS_1984.prj file.
If the Coordinate Systems folder is not displayed, go to Tools > Options > General tab, and check the Coordinate Systems check box in both the upper and lower windows.
- Right-click the .prj file and select Copy.
- Select Paste to paste the file into the same folder.
- Right-click the copy, select Rename, and name the file 'idl.prj'. These initials stand for 'International Date Line'. Another name can be used.
- Double-click the .prj file icon to open the projection file. The name must be changed in the Name box at the top of the dialog box. Use the same name that was assigned to the external file, but without the PRJ extension.
- Open the Datum drop-down list, and select <custom>.
- Open the Spheroids drop-down list, and select <custom>. Do not change the values shown for the semi-major axis, semi-minor axis, or inverse flattening ratios.
- At the bottom of the Geographic Coordinate System Properties dialog box, open the Prime Meridian Name drop-down list, and select <custom>.
- Change the Longitude value from 0 0 0 to -180 0 0 and click OK.
- Open an existing map document with data currently in a data frame.
If this procedure is used with a data frame with no data in it, it is necessary to add data to it that has its coordinate system defined before proceeding to Step 6.
- Select View > Data Frame Properties.
- Select the Coordinate System tab.
- Navigate to the custom .PRJ file created in Step 1 above in the Select a coordinate system section of the Data Frame Properties dialog box.
- Click the Transformations button.
- Click New in the Geographic Transformations dialog box.
- Accept the default method Geocentric Translation, and the zero values for the three parameters by clicking OK.
- Click OK in the Geographic Coordinate System Transformations dialog box.
- Click OK in the Data Frame Properties dialog box.