Point Data in Text Format (CSV files)
For point data observations, data values associated with observations at scattered or random latitude-longitude-altitude locations, the IDV can read data in a kind of plain text file called an IDV csv file. An "observation" can be an event such as an earthquake, or a volcano eruption.
The format is shown in examples below. The files have one observation per line, with comma separated values, hence the files are called csv files. The files have a special header that tells the IDV what is in the file: field names and units, and how they are related.
The files must end with the file extension ".csv" -- that is how the IDV knows the file format and how to read it. The files must have a time value, and must have one data value of some kind per location (line), even if it is just a dummy value such as all zero magintudes for earthquake locations. A file of only latitude, longitude, and altitude (depth) values will not be accepted by the IDV.
IDV csv files can have one or more fields (types of observed values) for each observation. One or more time can apply to each location; each time is of course a different observation (line in the file). The IDV can show time animation or all values at once, in one display.
How the observation values are plotted in the display -- what point symbols they use -- is determined by a "layout manager" or "station model." See Point Data Plots.
Here are sample csv files, some with "real" data. Choose one and modify the data values for your use. The field names used for seismicity, focal mechanisms, gps vectors, seismic anisotropy, and strain are special words the IDV recognizes; for those data types do not change the field names in the two header lines. If your data type is not one of the geophysics examples, you can use your own, new, different, parameter names in the file and the IDV will be able to plot it with a variety of symbols. The geophysical examples are for data cases which have special symbols in geophysics and in the GEON IDV (not available in the base IDV). Do not alter the header, except to change the field names and unit names if you revise an example for another type of data.
generic example with four fields
GPS vectors and error ellipses
Note that depth is negative downwards below the "surface" (value 0) in these csv files. Longitude west is negative, or has positive values more than 180.0.
Making a point data csv file with the IDV
If you have point data in another format that the IDV displays (NetCDF), you can make a csv file equivalent with the IDV.
In the Dashboard window, use the Fields tab. In it's "Displays" area, click display type "Point Data List" and click "Create display." In the display control window that shows the list, click on "Select Fields." Add all the fields in the All Fields column to the Current Fields column with the Add button, and click on OK. Click on the "Show raw data" checkbox (or the IDV will round your data values to nearest tenths). Then do File->Save->Export Table, and enter a filename ending with .csv.
Comments or questions about this page? Send e-mail to Chuck Meertens (meertens
unavco.org).
