New Projected Coordinate System

Use the Coordinates > New Projected Coordinate System menu option (NEWXY GX) to create coordinates in a different coordinate system from existing coordinates.

Expand to see other locations (menus) where this option is available.

 

Gravity and Terrain Correction extension:

  • Moving Platform Gravity > Import menu

UXO-Marine extension:

  • UXO-Marine Sonar Utilities menu

Target:

  • Surface Mapping > Coordinates > Select Coordinates menu

The dialog is implemented as a wizard that has four steps:

  1. On the Enter Existing Coordinate Channels dialog, identify a pair of existing coordinate channels (normally "X" and "Y"). You can also specify if you want to process "All lines/groups" or only the "Selected lines/groups". Click Next.

  2. If only the selected lines/groups are processed, the system will assume that all data in the output channels is in the new projection.

  3. On the Coordinate System dialog, verify the coordinate system information:

    • If the provided X/Longitude channel and Y/Latitude channel values (from the previous dialog) exist, the selection dialog (Coordinate System) is populated with the existing coordinate system defined for these channels.
    • If the coordinate system has not been established, the Type field will be set to "Unknown", all the other entries in the 'Coordinate System' section are blank, and you will have to select the appropriate coordinate system (CS) in this dialog. See the Coordinate System topic for more information. Click OK.

  4. On the Coordinate Channels to Create or Update dialog provide the new coordinate channels. This can either be a pair of new channels, or existing channels but different from the input channels. Click Next. If the channels exist, you will be prompted to overwrite or not.

  5. On the Coordinate System dialog, define the new coordinate channels. Select the desired projected or geographic coordinate system from the Available Coordinate Systems list. You also have the option to inherit the projection of another file (the Copy from option) as well as copy the current projection to another file (the Copy to option). If your two coordinate systems are on the same datum but have different defined Local Datum Transforms (LDT), you could go through the Modify option to transform between the Local Datum Transforms. See the Help content associated with the Coordinate System dialog for more information. Click OK.

The new projected/geographic coordinate channels will be created from the original coordinates.

Application Notes

  • In many cases you will not want to alter coordinates already located on a datum. One situation where you may want to do this is where you know that the coordinates were originally collected in WGS84, and the LDT defined in the existing coordinate system was used to locate these coordinates on this datum.

    • Many functions in Oasis montaj will use the designated "X" and "Y" channels information to determine the spatial location of data points. The designated default "X" and "Y" can be changed to a new coordinate pair using the Coordinates > Set Current X,Y,Z menu option (XYSET GX).

    Previous versions of this GX enabled you to transform coordinates from Datums based on the Geoid to earth-centered Datums. However, this limited the use of geoid-based elevations to non-earth-centered Datums. It is sometimes desirable to use geoid-based elevations on earth-centered datums, such as WGS84 (or any GRS80-based datum). For this reason, the elevation transform function has been removed from this GX. A new GX named "GEOID" can be used to create a Geoid height channel in your database. If you wish to convert an elevation relative to the ellipsoid to an elevation relative to the Geoid, subtract the Geoid height from the elevation channel. See the GEOID Height topic for further information.

    See Also: