Re: 20030730: Plotting points in IDV

Hi Kevin-


> > I'm interested in overlaying accident locations and/or aircraft tracks
> > (lat/lon points) onto data in IDV. 

For station locations, you could create an XML file with the
geolocation information and name and description.  The format
would be (accident.locs):

<stationtable name="accident locations">
<station idn="" id="7XGWF" name="piper cub accident" lat="39:34:12" 
lon="-119:47:24" elev="0"/>
<station idn="" id="8SCF" name="mooney accident" lat="38:34:12" 
lon="-120:47:24" elev="400"/>
</stationtable>

(units of altitude are meters, format for lat/lon can
be any valid McIDAS lat/lon format (theoretically at least ;-)).

Then, you would need to create an alternate properties file
that would point to this that would contain the line:

##The list of station table xml files
application.resource.locations = 
%IDVPATH%/nexradstns.xml;%IDVPATH%/profilerstns.xml;c:/accident.locs

(put it wherever you want).  The first two files listed are the
defaults, you can leave them off if you don't care about plotting
those locations.  You can add as many as you want, separated by
semicolons.  You could put them in your IDV home directory
<userhome>/.metapps/DefaultIdv and then use %USERPATH%
as the path to the file.

Then, if you are using the InstallAnywhere version of the IDV,
you would go to the directory where idv.jar is installed and
run:

jre/bin/java -Xmx512m -jar idv.jar -properties c:/myidv.props

(or whereever you put the file; reverse the slashes for
Unix systems).

If you are using the WebStart version, let me know and I
could figure that one out as well.

Once you have the IDV running, go to the Displays/Stations menu
and select the station table you want.  You can then control the
marker and the label you want for each location.

For an aircraft track, you could put that in a netCDF file and
read it in as a track file.  The CDL looks like:

ncdump p3_1.nc
netcdf p3_1 {
dimensions:
        time = UNLIMITED ; // (10 currently)
variables:
        double time(time) ;
                time:units = "seconds since 1970-1-1 0:00:00 0:00" ;
                time:long_name = "Time offset from base_time" ;
        float altitude(time) ;
                altitude:units = "km" ;
                altitude:long_name = "altitude MSL" ;
        float latitude(time) ;
                latitude:units = "degrees_N" ;
                latitude:long_name = "north latitude" ;
                latitude:valid_range = -90.f, 90.f ;
        float longitude(time) ;
                longitude:units = "degrees_E" ;
                longitude:long_name = "east longitude" ;
                longitude:valid_range = -180.f, 180.f ;

}

Load in the file as a track file and then plot the track of
altitude

> > Is there an easy way of doing this? I also have height (altitude) data for
> > aircraft track points. Is it possible to plot the
> > points in 3D along with meteorological data (e.g. gridded data)? I'm sure it
> > is possible. What's the best way to 
> > go about doing this?

It's not pretty, but it should work. ;-)

Don
*************************************************************
Don Murray                               UCAR Unidata Program
address@hidden                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
*************************************************************