Coordinate and Datum Transformations

With this Java application, you can convert between geographic and UTM coordinates, and you can convert coordinates between a variety of geodetic datums.

Pay close attention to the error estimates. The tool may display coordinates to millimeter precision, but most datum transformations supported by this application are accurate only to meters or dekameters. Conversions between geographic and UTM coordinates are accurate to centimeters or millimeters.

Error values of -1 indicate that no error estimates are available.

This is a Java 1.1 application. Some older versions of popular browsers still in use do not support Java 1.1. See the Performance Issues section of the instructions for more information.

[The Coordinate and Datum Transformations tool requires a Java 1.1-capable runtime environment.]

The previous version of the tool, Version 1.1, is available here.

If you happen to see curious background color changes (namely between gray and white) in the coordinate entry fields, I'm aware of them. I believe they're harmless but will get the colors to be consistent as soon as I can.

If you're using a graphical browser, you may want to display the instructions in a separate browser window. Consult your browser's documentation for details on opening a document in a separate window.

Additional Datum Transformations

The source for the original set of datum transformation parameters supplied with this tool is NIMA TM 8350.2 (see the bibliography). However, I have added a couple of transformations that do not appear in that reference. You are encouraged to test them thoroughly with known stations before using them for important work.

Transformationdxdydz exeyezCitation
Rijksdriehoeksmeting (Netherlands)-593-26 -478unkunkunkunknown
Jamaica 1969652123871 11Mugnier, Cliff, "Grids & Datums: Jamaica". Photogrammetric Engineering & Remote Sensing, 69:5 (May 2003).

Note also that these are not the only sets of local-to-WGS84 transformation parameters in existence for these datums. You may know of others that are close but not identical to these.

Transformation Source Code and Downloadable Version

I'm occasionally asked about source code for the datum transformation. Source code for the Molodensky transformation used by the tool can be found here.

The source code for the rest of the tool isn't published at this time.

For a downloadable datum transformation tool, at present I recommend the GEOTRANS program from NIMA. GEOTRANS runs on Windows and UNIX systems and supports several projections, not just UTM.

Eventually I'll be upgrading my tool to incorporate some of GEOTRANS' features while still maintaining the advantages I enjoy with my implementation. In the meantime, enjoy the fruits of my tax dollars.


Chuck Taylor -- (Copyright) -- (Contact)