PBO GPS Velocities in Southern California; click for full size image 		The GEON Integrated Data Viewer - Contents

INTRO                 Introducing the GEON IDV

INSTALL               Download & Run the GEON IDV

LEARN                 Tutorial ... How to Use the GEON IDV ... Bundles

DATA                   Geophysics Data Types and Sample IDV Displays

YOUR DATA         Data Formats for the IDV

EDUCATION         Ideas for using the IDV in Education

CONTACT             UNAVCO

GPS Data in the GEON IDV

The GEON IDV can display GPS velocity vectors and error ellipses, and overlay the velociy plots on other geophysical data, including 3D topographic relief.

Your copy of the GEON IDV must use a "GEON IDV plugin" made March 24, 2009 or later. Uninstall any older GEON IDV plugin from your IDV, and re-install the plugin, which will get the latest one. Use the IDV --> Tools --> Plugin Manager menu choice. In Custom plugins, choose install or uninstall for the GEON IDV plugin. You will need to restart the IDV after both steps. This process will install a new GEON IDV plugin with new code. For the plugin manager, see Plugins, which may help a little. If you have an older copy of the IDV you may need to upgrade the entire IDV to version 2.6u2 (March 2009) or later (see INSTALL in this web site).

The IDV can also display time series of GPS station position displacements (north, east and vertical components, and their error estimates with time).

GPS velocity vector data may have 2 components (east and north), or 3 components including vertical, and in that case the IDV will plot GPS vectors in 3D. An overhead map view will show only the horizontal vector in either case.

Put Your GPS Velocity Data in the GEON IDV

click for full size

Look at this sample GPS velocity vector data file for the GEON IDV. Each line is one station's values and the values are separated with commas. The IDV requires time and altitude for each observation and in this example those values are are set to one time and one altitude (0). There is no vertical velocity value. There is a 4-character station label 'IDN.' This data format allows plots of velocity vectors (from ve,vn) and error ellipses (from sigx,sigy,corrxy),

This sample data file includes time, altitude, and vertical motion components at each station, but no station id. vz downwards is negative.

Put your data in a file with one of these formats, with the same two header lines, and the same units. Keep the filename extension 'csv.' For more about this file format for the IDV, see the Unidata IDV User's Guide: Text (ASCII) Point Data Format..

Time is required by this format, but you can of course use any time you like, including a dummy or placeholder value. Tine is used by the IDV to merge separate data sources at one time in one plot, or for time animation.

Making a Display

Load your data file in the IDV with the Dashboard window, Data Choosers -> Files, and find your file. Click on "Add Source."

In the dashboard "Fields" panel in the center, click on "Point Data." For "Layout model," choose one of the "GPS vectors" choices. Click on "Create Display." See also Making GPS Displays - More Details. Note that in the overhead view (CTRL-R) you cannot see the vertical component of velocity.

Here is an IDV bundle file that should make a GPS display in your IDV after you add the new GEON IDV plugin. It uses the sample data file shown above. Load it with the URLs window in the Data Choosers.

PBO GPS Velocities


    GEON IDV display of PBO GPS velocities, USGS surface fault lines, and JPL "Blue Marble" satellite image.
    Click to see full size.

    Original Data Source:
    The original or source for the GPS velocity data for the PBO stations, the combined products from the GPS Analysis Center at MIT (the best quality results; the PBO data file "pbo.final_frame.vel"), is online at PBO GPS Products. Do "save link target as" for the link CSV under the "Network Velocity" icon in the lower right. Details about this data are available from the The PBO web site. There are more than 1100 stations in this data set. These vectors are relative to the North American reference frame (SNARF). This data file can not be read by the IDV; it needs a different header.

    GEON IDV Data Source:

    The same PBO "pbo.final_frame.csv" data with a modified header for GEON IDV use is here: http://geon.unavco.org/unavco/GPS/pbo_final_frame.csv.

    To load this data source into the IDV, just copy the link location (URL); you do not need to download the file. Enter the URL in the URLs entry box in the IDV Dashboard's "Data Choosers" window. Click on Add Source. In the dashboard "Fields" panel in the center, click on "Point Data." For "Layout model," choose "GPS vectors"(black or red). Click on "Create Display." to make a "Text Point Data" display. Change the "Location Model" (in the display control) "GPS velocity vectors" (red or black). In the display control for the "Text Point Data" display, click on the "Times" tab, click on "Show: Multiple" to see all data times in one display. To declutter (see all vectors), in the "Layout" tab, click off the "Declutter" check box.

    This IDV bundle file when loaded in the GEON IDV will make this display:

    click for full size

    Sample PBO data displays:

    PBO Pacific Northwest GPS velocities, relative to North American plate

    PBO velocities, western US, low oblique, including vertical motions

PBO GPS Station Time Series


    click to see full size

    You can plot time series from GPS stations in the IDV, for the PBO nretwork and a few others around the globe. You click on the station symbol on the map, for the station of interest.

    Original Data Source:
    The source of time series data is the web page PBO GPS Products. Do "save target as" for the "Position Time Series" link. This is a gzip-tar file. Unpack the file to see lots of the .csv files, one for each station. The header lines must be reformatted to work in the IDV. See the section "Reformatting PBO GPS Time Series Files' Header for IDV Use" below.

    IDV Data Source:
    Time series data files for each of the individual PBO stations, formatted to work in the IDV, are online at PBO time series station data files for the IDV. There are 1255 stations. Use an IDV station plot, as shown above (in "PBO GPS Velocities"), to find the names of the stations of interest to you. In the PBO time series files, do "copy link location" for a station file of interest. Enter that link location in the URLs entry box in the IDV Dashboard's Data Choosers window. Choose Data Source Type of "Text Point Data Files." Click "Add Source." In future we hope to provide a way for you to click a station on a map and see the IDV time series display for that station.

    Create a "Point Data Plot" display. In its display control, do View->Undock from Dashboard. Click on the Plot tab. Now you can resize the plot by resixzing the window. In the map display, click on the symbol at the station where you want to see the time series. In the display's control, Plot panel, you should see the station name and location appear in a list below the chart; DOUBLE click on a variable name (in that same list as the station name) to plot the time series of that variable.

    Do a right click on each variable name in the list to remove, or add, that variable to the time series plot. Do View->Chart->Chart:(chart title)->Zoom In->Domain Axis to zoom in along the time axis (shorter time range). To add a title to the plot, right click on the time series plot, choose mednu choice Properties. In the Name entry box add your title. To save an image of the chart, do View->Chart->Chart:(chart title)->Save chart as.

    Sample IDV displays:

GPS Vel 1.0 ITRF 2000" Velocities

Reformatting PBO GPS Time Series Files' Header for IDV Use

This section is in case you want to make your own data files. The standard data is already converted and available as described above.

The source of time series data for these GPS stations, is PBO GPS Products. Do "save target as" for the "Position Time Series" link. This is a gzip-tar file. Unpack the file to see lots of the .csv files, one for each station. The header lines must be reformatted to work in the IDV. 

    To modify a PBO station  time series data file to use in the IDV, the header lines such as

PBO Station Position Time Series
Format Version,1.0.1
4-character ID,ELKO
Station name,ELKO_BRGN_NV1997
Begin Date,2004-01-07
End Date,2008-07-28
Release Date,2008-07-30
Reference position,40.9146904918 North Latitude,-115.8171979278 East Longitude,2016.89028 meters elevation,
Date,North (mm),East (mm),Vertical (mm),North Std. Deviation (mm),East Std. Deviation (mm),Vertical Std. Deviation (mm),Quality,

(from ELKO.pbo.csv)

are replaced with 2 lines describing the data character and 4 lines about the station.  Do not alter the caps as in Latitude

(index) -> (Longitude,Latitude,Altitude,Time,Station(Text),North,East,Vertical,Nstddev,Estddev,Vstddev,Quality(Text))
Longitude[unit="degrees east"],Latitude[unit="deg"],Altitude[unit="meter"],Time[fmt="yyyy-MM-dd"],Station(Text),North[unit="mm"],East[unit="mm"],Vertical[unit="mm"],Nstddev[unit="mm"],Estddev[unit="mm"],Vstddev[unit="mm"],Quality(Text)
Longitude=-115.8171979278
Latitude=40.9146904918
Altitude=2016.89028
Station=ELKO_BRGN_NV1997

You might name the new file ELKO.pbo.idv.csv.
    Here is a sample PBO time series file for the IDV, witrh two stations, ELKO and TRND.

Making Displays - more details

First set the display to a map projection (map area) and a vertical scale suitable for your data. If you are only showing data on the surface, in overhead views, the vertical scale does not matter. Be sure the menu choice Projections -> Auto update projection is checked off.

Connect to a data source with the "GEON IDV Dashboard" window, "Data Chooser" tab. For local files choose the "Files" section, navigate to the file on your local disk, choose the Data Type from the pull down menu, and click "Add source." For data sources with an HTTP server, use section "URLs." If your data is in a .csv file, use Data Type "I'm feeling lucky" which means the IDV recognizes the data type from the file name extension. If your data file is a NetCDF (.nc) file, choose Data Type "NetCDF Point Data files."

After you connect to a data source the Dashboard shows the "Field Selector" for that data. To make a display, in general you choose (click on) a Field name in the "Field Selector" tabbed panel in the Dashboard, then click on a display type in the Displays panel of the same window, and then click on the "Create Display" button.

GPS station data is Field type "Point Data," and the Displays panel shows the choice "Point Data Plot" and "Point Data List." Click on one, then click on the "Create Display" button.

When a display is made the Dashboard shows the "display control" panel for that display. Note the pull down menu called "Layout Model" or "Station Model" which is a list of the plot symbols available for all kinds of data. At first a Point Data Plot display will use plot symbols called "Locations 3D Cross," or whatever happens to be first in the "Layout Model" list. To use another plot symbol, choose one from the list. For GPS velocity vectors, use "GPS Vectors, red" or GPS Vectors, black." (You need the GEON IDV plugin of March 6, 2007 or later to get both colors and vertical components.) Get the latest plugin from the GEON IDV download page.

You can control vector length scaling, using the "Scale" entry box in the Display control window that pops up when the display is made. The Declutter check box reduces the number of symbols in the display. Read more about Point data plots and Working with the Point data Plot Symbols using "Layouts Models"

To zoom, pan, and rotate see Zoom, pan and rotate.