Coordinates transformation with GEOTRANS 

One of the most common operations done with species primary data (like those found in natural history collections or observations databases) is to transform coordinates between different systems. Due to the current need for tools and manuals, we present here one of the existing alternatives to carry out this kind of task.

There are several transformations you can perform, but here we are going to illustrate here the transformation between three kinds of coordinates:

• UTM (s.s.): Universal Transverse Mercator. Structured in zones, they tipically limit a square of 1x1 m with two coordinates. Example: 29N 729325E 4645921N.
   
• UTM (MGRS): Military Grid Referencing System. A subsection of UTM, they define an area whose precision is determined by the number of figures included. Typical examples could be 30TUL54 (10x10 Km area) or 31TDG0306 (1x1 Km area).
   
• Geographic Coordinates: They are the most common ones. They are composed of two components (latitude and longitude), usually recorded in degrees, minutes and seconds, or only in degrees with decimal digits.

If you need further information about geographic terms, you can check some of the glossaries available on the net.

The software we are going to use to carry out the transformations is GEOTRANS from the United States National Geospatial intelligence Agency. This software can be downloaded without charge from their website: please, check GBIF.ES mapping tools section to access these contents.

Once you have downloaded and installed the software, the process will be different depending on the format of the original coordinates available: the processes for the three systems mentioned above are described bellow. There are also different sections for individual coordinates and for massive transformations.

First of all, you must launch the program running the file "GeoTrans2.exe" (binary version), or "Geotrans2.jar" (Java version). As a general rule, in the upper part of the window we'll setup the original coordinates we have, and in the lower part the type of target coordinates we want to obtain (this process can be inverted, though).

The values you have to use as ORIGIN for the different coordinates types are: (click on the header to see an image of the application set up with those values).

If you choose Geodetic output format, you must define the wished format for the geographic coordinates: In Options menu, under the Geodetic Units section we have three options: the most common ones will be Degrees/minutes/seconds DDD/MM/SS.FF, or Degrees DDD.FFFFFF. We can also define the separator character between the different compounds of every coordinate: also in Options menu, under Geodetic Separator section we can choose between a space, a slash '/' or a colon ':'. To finish you must define if you want your coordinates provided with sign or with direction indication (E, N, etc.) in Sign / Hemisphere section of the Options menu.

To perform massive transformations of several records at the same time, you need to include them in a file containing the configuration information of the original data. You can find here example header files for European 1950 Datum, for data recorded in geographic coordinates, UTM coordinates and MGRS coordinates.

You only need to include the list of coordinates you want to transform after the file header.

Once again in GEOTRANS software, choose the Open option inside File menu. Choose the file you have just made up, and accept. A new window is opened: you can check the configuration data extracted from your original file in the upper part. Select in the lower part the type of coordinates you want to obtain and click on Ok. Choose a name for the file where your transformed data will be stored, and click on Start in the new window which appears, to begin the process. Once the process is finished, you'll be informed about the number of records processed and about the errors encountered.

The output file is organized in columns, separated by spaces: you can import it directly from your database software, or you can do it through spreadsheet software like MS Excel®.