This material is obsolete. Please see: GEON IDV Data Formats and Access Methods


UNAVCO's ASCII Data Formats and Converters for NetCDF

    The IDV reads gridded data -- latitude-longitude-depth or x-y-z -- from NetCDF format files. NetCDF files include user-defined metadata describing the data, in particular its mapping on the Earth, and units and names for variables. (You can read lots of details about NetCDF.)

    As a convenience for GEON IDV users who write gridded data in ASCII files, UNAVCO provides two format converters to make NetCDF formatted files from certain ASCII formats.

    The format converters run on any system that runs Java and NetCDF code. If you can run the IDV, you can run the converters. You can include conversion to NetCDF in routine creation of ASCII files, to make equivalent NetCDF files for IDV use.

    The IDV can read point data from ASCII files directly, in a special format, or from NetCDF files. Below is described the GIAP ASCII format for point data and a converter to move it to NetCDF.

The UNAVCO online interactive ASCII grid data format converter to NetCDF

    This converter accepts several formats of ASCII data, but is limited to one parameter per grid. You may be able to convert data files you have now to NetCDF with this converter.

    The UNAVCO online interactive data format converter for ASCII list and column data files has a user interface where you enter control values to convert one data file with one parameter, in any of several ASCII formats, to a NetCDF file. This may be useful in converting some existing ASCII data such as the NGDC topography data

GIAP: ASCII format for Point Data with independent longitude & latitude

Point data for the IDV is now stored in ASCII 'csv' files. see http://geon.unavco.org/unavco/IDV_for_GEON_csv.html

Examples of point data in the GEON IDV include GPS Vectors, Earthquake locations, Earthquake focal mechanisms, and Tectonic plate velocity vectors.

    This format and coverter is left here in case it of sue to anyone, but most any point data can be read by the IDV directly from ASCII files with the correct herader, without conversion to NetCDF. When the GIAP format and converter were devised, that was the way to get point idata in to the IDV. Since then demand for paint data has grown and the IDV can read simple ASCII files directly.

    The GIAP format is a simple ASCII file for "point data," data where every location has an independent latitude, longitude and depth position, not on a regular grid. Several parameter variables and a time value can be provided at each point. For time animation you could have several "points" - lines in the file - at the same exact lat-lon-depth location, with differing time values. Typical examples of data suitable for this format include:

  • point observations such as GPS vectors, strain measurements, etc.
  • natural events such as earthquakes
  • soundings such as borehole data

    The GIAP format description is online at GIAP format.

    Format Converter for the GIAP Format

    The format converter program to convert GIAP ASCII files to NetCDF can be downloaded here. (You need Java to run the converter - and you probably already have it to run the IDV. If you need to get Java, see the system requirements for the GEON IDV.)

    Linux Format Converter

    For the Linux GIAP format converter, download the GIAPconverter.jar and ncgen for Linux into the same directory. Make sure ncgen has execution privilege.

    To run the converter, in its directory, do a command like
    java -Xmx512m -jar GIAPconverter.jar /home/my/full/path/gps_vectors.giap

    /home/my/full/path/gps_vectors.giap stands for the complete path and filename for a GIAP data file.

    If java is not found, add the location of java to your PATH environment variable, or use the full path for the java program, such as /usr/java/java1.4.09/bin/java

    The program will print output to the screen, state whether the process succeeded, and show the names of two files made, a ".cdl" file and the NetCDF ".nc" file.

    You will find, in the directory with your original GIAP file, the two new files, such as gps_vectors.cdl (the new CDL file) and gps_vectors.nc, the new NetCDF data file which is what the GEON IDV needs.

    Windows Format Converter

    Download the GIAPconverter.jar Get the NetCDF utility program "ncgen" for Windows from the NetCDF package. Make sure ncgen is in the same folder as the converter program. You will need to execute the program with a command line like described under Linux above, in ".bat" file.

    See Correct Attribution of Your Data, and GEON Search below if you are going to supply this data to the GEON portal, to make sure the data file contains your attribution.

    Solaris Sun systems

    Download the GIAPconverter.jar. Get the NetCDF utility program ncgen for Solaris from the NetCDF package. Make sure ncgen is in the same directory as the format converter program. Execute the program with a command line, like described under Linix above.