1.1. What is the IDV?
The Integrated Data Viewer (IDV) is a framework for
visualizing and analyzing geoscience data. The IDV release includes a
Java-based software library, and applications made from that software.
It uses the VisAD
library for data and display models as well as other Java utility
packages. It was developed at the Unidata Program Center (UPC), part of the
University Corporation for Atmospheric Research, Boulder, Colorado, which
is funded by the National Science Foundation. The software is
freely available under the terms of the GNU Lesser General Public License.
The IDV brings together the ability to display
and work with satellite imagery, gridded data (primarily from model output),
and surface, upper air, and radar data within a unified interface.
The IDV "reference application" provides many of the standard
2-D data displays that other Unidata packages (e.g. GEMPAK and McIDAS)
provide. It also provides 3-D views of the atmosphere and allows users
to interactively slice, dice, and probe the data to create cross-sections,
profiles, animations and value read-outs of multi-dimensional data sets.
Computation and display of built-in and user-supplied formula-based
derived quantities is supported as well.
It includes an integrated HTML interface that can be used to create
HTML based users interfaces to drive the displays, or to embed IDV
displays and controls directly in an HTML document.
1.2. Is the IDV still under development?
Development of the IDV is ongoing at the UPC and as it
progresses new features will be added and any problems/bugs will
be fixed. The development will be driven by the needs of the
community of users. Suggestions, comments and collaboration are welcomed
and encouraged. The goal is to provide new and innovative ways
of displaying and analyzing data, as well as provide the common
displays that many users have come to expect.
1.3. I'm submitting a paper for publication and want to include a citation for the IDV. What reference should I use?
The following can be used as a citation:
Murray, D., J. McWhirter, S. Wier, S. Emmerson, 2003: The Integrated
Data Viewer: a Web-enabled application for scientific analysis and
visualization. Preprints, 19th Intl Conf. on IIPS for Meteorology,
Oceanography and Hydrology.
2.0 Downloading and Starting with Web Start
2.1. I couldn't download the IDV. Is the server down?
Usually an inability to download the IDV and
other Unidata software is due to a failure by your system to correctly
identify itself to our server.
Both our server and the system trying to download Unidata software
have a "name" (domain name or host name or server name) and an IP address.
For example the address 22.214.171.124 is the same as the server with
As a security measure many servers only reply to requests from systems
whose address can be matched to a name using "reverse lookup " -
turning the numbers into a name.
"Forward lookups" find the IP address of any given host name. The
reverse action is resolving IP addresses into host names. If our server
cannot resolve the requesting system IP address into a name, no software
will be sent to the requesting IP address. If you are having problems
downloading the IDV from our server, check with your local system
administrator to make sure that your machine has reverse lookup enabled.
If not, download the IDV from a system that does.
2.2. When I first run IDV through Web Start, it asks me to accept a certificate? What should I do?
When you first download IDV through Web Start, you will see a message
This application is requesting unrestricted access to your local
machine and network.
Do you want to install and run: Integrated Data Viewer
Signed and distributed by: University Corporation for Atmospheric Research
Publisher authenticity verified by: Thawte Premium Server CA
Caution: University Corporation for Atmospheric Research asserts
that this content is safe. You should only install and run this application
if you trust University Corporation for Atmospheric Research to make
If you trust Unidata to make safe software, click the
2.3. How can I get updates through Web Start?
When starting the IDV using Web Start, the latest version of all
IDV code is found at the Unidata server, and it is automatically
downloaded and installed if it is newer than the version you have on
2.4. How can I change the amount of memory used by IDV through Webstart?
The amount of memory used by the IDV is hardcoded in the Web Start JNLP file
that is used to launch the IDV. If you would like to run IDV via
Java Web Start with a modified memory alloaction, simply right click on the
"Click here to launch the IDV" link on the IDV's Web Start page
and save the file (e.g., idv.jnlp) to a convenient location. Then, open
this file with an editor (e.g., WordPad, gedit) and modify the line
"<j2se version="1.6+" max-heap-size="1024m" /> to
reflect your memory need. After saving, you need only to launch this
.jnlp file to run IDV via Java Web Start with the modified memory allocation.
Please see the FAQ item below
for more information on
changing the memory allocation.
2.5. How do I use the Web Start Applications Manager?
For more control of the Java Web Start IDV installation, use the Web Start Applications
Manager. Launch the Applications Manager by clicking here
You will see the IDV listed in the Applications Manager panel.
You can use the Applications Manager to start
the IDV without going to the Unidata Java Web Start
link. In addition, with the Applications Manager, it is possible to remove broken
or out-of-date IDV installations (see following FAQ item.)
2.6. How do I remove and re-install the IDV from Java Web Start?
If your Java Web Start IDV installation is broken or out-of-date, remove it with
the Applications Manager. The Applications Manager will have a panel showing
"Integrated Data Viewer <version>" with an icon. Click to
select it. Use the Remove (X) button located at the top of the panel. The IDV
item be deleted.
In addition, it may be necessary to clear out Java Web Start
cached resources. Delete the jar resources that are found beneath the Resources
pull-down menu item (just below Applications menu item.)
Finally, reload the IDV from Unidata.
Note that you can verify the version of the
IDV in the Applications Manager panel. The "Integrated Data Viewer" item is
listed with a version number after it.
2.7. How can I show the Java console when running with Web Start?
When you start the IDV using Web Start, you don't have a console window
opened by default. You can enable the Java console through the Web
Start Applications Manager. Bring up the Web Start Manager
(Java Application Cache Viewer) as described above
Use the menu to bring up the Preferences dialog.
Click on the Advanced Tab and expand the Java Console item in the tree. Select
the "Show Console" option and then click the OK button. The next time
you start the IDV with Web Start, you will get a console that will log
messages. Messages are also logged to the IDV console. See the
for information on using this feature.
2.8. Can I serve up JNLP bundles from my own web server?
You can save a bundle as a JNLP file by using a .jnlp extension
in the menu dialog. Once you have the
file, you can place it on your web server and create a web page
that points to it. Your web server must identify this as a JNLP file,
so if it doesn't already support this, you'll need to configure your
Web server so that all files with the .jnlp file extension are set to the
application/x-java-jnlp-file MIME type. Each Web server has a specific
way in which to add MIME types. For example, for the Apache Web
server you must add the following line to the .mime.types configuration file:
Check the documentation for the specifics of your Web server.
3.1. How can I tell if the IDV is busy doing something?
The lower right corner of the main IDV view window shows a box with
progress bars when the IDV is busy making a display or doing anything. In
the status bar at the bottom, messages will appear when the IDV is reading
data from a server or disk. Also, while the displays are being created,
there is usually a "please wait" notice in the lower left corner
of the main display.
3.2. How can I save a display?
You can save images of displays as JPEG or PNG files or animations
as Quick Time movies or animated GIF's.
See Image Captures
You can save particular IDV state with all displays, including data
sources, displays, maps, map projection, view point, and color tables,
by saving a "bundle" file with the
menu, and naming a file.
See Saving State with Bundles. A bundle file lets
you reset the IDV to exactly the same state as before. The file can
be emailed to others to recreate your IDV display, provided they have
access to the same data source.
Using the favorite bundles
with menu you can
save and use several configurations which are retrieved with the
3.3. How can I change the start-up settings?
You can customize many of the IDV properties through
menu. The preference
manager allows you to configure the many features of the IDV.
You can also create a default IDV state and save it off using the
bundle facility. This allows you to override the preferences and
also include datasets and displays to load when the IDV starts.
To save a default bundle, use the
See Saving State with Bundles.
3.4. How can I change the amount of memory available to the IDV?
By default, the IDV startup script (runIDV
(Windows)) tunes the amount of memory allocated
to the IDV according to system parameters. On 64 bit computers, the memory
allocation amount is 80% of the available RAM. On 32 bit computers, the
amount is the minimum of 1.5GB and the available RAM minus 512MB.
In addition, users can change the memory settings in the ,
System tab. In order for these changes to take effect, the user will have to
restart the IDV.
In rare circumstances, the IDV start script cannot determine the optimal amount
of memory for the IDV. In this unusual case, the IDV start script allocates 512MB.
The user can still go to the , System tab and adjust memory
settings. Again, the user must restart the IDV in order for this to take effect.
In other exceptional situations, the user may still wish to override the automatic
tuning mechanism. In the body of the runIDV script, there are instructions on how
to achieve this change, although this should rarely be necessary.
3.5. How can I change the size of the IDV window?
You can save particular IDV set-up including map, projection,
With the IDV running, move and re-size the display and data source
windows to the arrangement you like. Save the
"default bundle" with the
When you next start the IDV the same arrangement will appear.
3.6. How can I reset the map projections?
When new data is displayed, the map projection will be automatically
switched to match the native projection of the data. You can control
this with the
You may not want this, especially when you have
set up a view of a particular area which will be lost when new data is
loaded. Check it off if you don't want it.
You can switch an existing display to its native data set projection
using the display control's menu.
3.7. How can I set the default projection?
You can select a default map projection with the Projection Manager
which is accessed from the menu.
Select one of the items in the Default
pull down list. The
default projection is overridden by a projection saved in the
, and by resetting the map projection
with new data if enabled. As a result, you may never see the
default map projection. Make sure your default bundle has the default
projection, and you have the menu item
menu checked off.
Choosing a default map projection is not necessary for good use of the IDV
and you can ignore it if you like. It is often simpler to use default bundles.
3.8. How can I change the color table range?
Many displays have a color table controlling the colors of data values.
A color table has a range of minimum and maximum data values. You
can change the range for a display by right clicking on the color bar
in the display's legend and selecting the
menu from the popup menu. For more information on controlling the
color table, see the Color
3.9. How can stop the IDV from asking if I really want to exit?
You can change many features of the IDV though the User Preferences
dialog. Use the
menu to bring up the dialog. On the
uncheck the "Confirm Before Exiting" box to stop the
IDV from asking if you want to exit.
3.10. When I set a color table transparent, why doesn't it show up that way?
Using transparency in a color display may give unexpected results.
In general, only the last thing added can be fully transparent.
If you have a display that is transparent, then add in a new display,
you may not see it. The problem is caused by the lack of ordering
in Java 3D. You can use the display control's View->Bring to Front
menu to remove and re-add the display that you want to be transparent
so it is last.
4.1. What is Fast Rendering and when should I use it?
By default, the IDV will try to adjust the data renderings to account
for projection seams. This is computationally intensive in some
cases and slows down the display of data. When you set your preference
to "Use Fast Rendering", the IDV will not try to account
for the projection seams. If you are displaying data in its
native projection, this will result in faster rendering of the data
depiction. However, if you have several displays of data, each
from a different data source and on a different projection, you may
see anomalies in the displays (spurious lines, portions of images).
At that point, you can turn off fast rendering for a particular display
using the Edit->Properties menu of the Display Control for that
display, or set your system preference back to not use fast rendering.
4.2. I have multiple Grib files, each holding a separate time. How do I animate these?
Normally the IDV does not try to merge the separate grid files,
it just loads them up individually as separate data sources. You then have to create separate displays for each time step. Furthermore,
in the IDV displays with just one timestep are always shown.
What you want to do is to select the multiple set of grib files in the File Chooser (using control or shift click)
and then select "Aggregate Grids by Time"
for the Data Source Type. This will try to aggregate the grid files on time and will produce one data source with a set of times.
Note: each grib file needs to be identical in terms of variables, projections, etc. They should only differ by time.
4.3. What is the difference between true wind vectors and regular wind vectors?
Some gridded data is produced with the wind components being
relative to the model grid instead of the earth. The true wind vectors
are rotated from the grid projection to actual (true) wind direction.
For non-projected (i.e., lat/lon grids), grid relative is the same as true.
4.4. What is the difference between the Standard Atmosphere
and logarithmic pressure to height conversion?
The IDV displays pressure surfaces by converting the pressure
to a height in some reference system. There are two reference
systems that come standard with the IDV - the U.S. Standard Atmosphere
and a logarithmic conversion (also used in Vis5D). The U.S. Standard
Atmosphere only computes conversions for pressures up to about 80 km.
The logarithmic coordinate system uses the following equations:
P = 1012.5 * e^( H / -7.2 ) (^ denotes exponentiation)
H = -7.2 * Ln( P / 1012.5 ) (Ln denotes natural log)
so can be used for heights above 80 km.
4.5. Can I view WRF model output in the IDV?
The Weather Research and Forecasting (WRF) Model output can be
viewed in the IDV. You have several options for displaying
the data. The IDV will read the native, staggered netCDF output
from WRF, however we recommend that you post-process the data
first. Using the native format is computationally and memory
expensive, since the IDV has to transform the data on the fly.
It is strongly recommended that you use one of the available
WRF post process programs (e.g., ARWPost, WRFPost) to destagger
the grids and compute the standard meteorological variables on
pressure or height coordinates. The IDV can read the GRIB
(1 & 2), GEMPAK and Vis5D output from these
4.6. Can I view Level III Radar data in the IDV?
The IDV can load Level III radar products from remote ADDE
and TDS servers using the Radar Choosers provided in the
reference application. It can also read many of the Level III
products (radial and raster) from disk using the Radar Files
4.7. Can I view Level II Radar data in the IDV?
The IDV can be used to create displays of WSR-88D Level II
radar data. The Level II data is supplied as volume-scan files, each file having all data from one WSR-88D radar
for all sweeps for one "time". Unidata
Community sites can receive Level II data using the
Unidata Local Data Manager (LDM)
. Archived Level II data is
available from the National
Climatic Data Center (NCDC)
The files should be stored on your file system with each station's files
in a directory (folder) whose directory name is the station
4-character ID (e.g., KTLX for Oklahoma City). In some cases the data
files do not have any location information in them and the IDV uses the
directory name as a first guess at the station location.
4.8. Why do I get an error when I try to load radar
data that I downloaded from NCDC?
There are few common problems that can cause this:
- The files are in a compressed tar file -
Typically, when you download Level II data from NCDC, the files
are in a compressed TAR file which holds the individual volume scans.
You need to extract the volumes from the TAR file with utilities
like tar, gunzip, WinZip into a directory as described in the
previous FAQ item.
- You are using the Files chooser
You should load the radar data using the Level II data
chooser in the Data Source Chooser, not the Files chooser.
In some cases, the files do not have any location information in
them. The Level II data chooser allows you to associated a station
location with the data file, using the directory name as a first
4.9. When I try to read in my GRIB data, why do I get an
For the IDV to read in GRIB data, it needs access to lookup
tables for decoding the information in the data. The IDV comes
pre-configured with most of the commonly used tables from NCEP,
FNMOC, etc, but some GRIB data from regional centers may use
tables other than the defaults. If the IDV does not have
the necessary table, you will get the NotSupportedException.
You can add in new tables by following the instructions in the
User's Guide section on
Adding in new GRIB tables
4.10. How are grids resampled in the IDV?
The IDV uses two methods for resampling data - weighted
average and nearest neighbor. These are the default sampling
mode for VisAD which the IDV is based on. For any grid,
the samples are organized in a topology, which may be
triangles (Irregular2D), squares (Gridded2D), tetrahedra
(Irregular3D) or cubes (Gridded3D). For target points
the system finds which topology element contains the
target. For nearest neighbor, it gets the values at the
vertex of that containing topology element closest to the
target point. For weighted average, its computes a
weighted average of all vertices of that containing
topology element, where the weights are bilinear in
2-D and trilinear in 3-D. (source: Bill Hibbard, SSEC)
5.1. Do I need a special video card to run the IDV?
Your video card must support OpenGL (or Direct-X if you are
using the Direct-X version of Java 3D). If you experience
problems with IDV displays (sets of triangles, spurious lines,
weird looking displays), make sure your video driver is up to date.
See your system's documentation for how to check that.
5.2. The display goes grey or gets corrupted when I resize my
IDV display. What's wrong?
ATI cards do not always play nicely with the OpenGL version of
Java 3D under Windows. If you experience problems with corrupted
displays (sets of triangles, spurious lines, weird looking displays)
and have an ATI card and are running Windows, try the following:
- Right click on the Windows Desktop and select Properties from the
- From the Settings tab, make sure the color quality is 16 bit.
- Click the Advanced button and select the OpenGL tab. Depending
on your card, either click the button for Force 16 bit buffer
(or something like that) or click on the Compatibility settings
button and click the "Force 16 bit" radio button.
- Click the OK buttons to exit the Display Properties dialog.
- Try the IDV again and see if it works better
- If not, try using the Direct-X installer instead of the OpenGL
5.3. The maps appear as a spider web of lines. What's wrong?
Starting with IDV 2.7, some computers are experiencing spurious map
lines in their displays. This seems to be a graphics driver issue being
tickled by a change in this and later versions. If you are experiencing
this, please use the ,
uncheck the "Enable geometry by reference" option, click
OK and restart the IDV. That should clear up the spurious lines.
5.4. I'm having problems with the OpenGL version under Windows.
How can I run the Direct-X version Java 3D?
If you are using the version of Java 3D distributed with the IDV
(1.3.2), you can switch between the OpenGL and Direct-X versions
of Java 3D with a command line switch.
If you are using runIDV.bat to start the IDV, edit that file and
uncomment the appropriate line. If you have your own script
for starting the IDV, add in the -Dj3d.rend=d3d option
to your start line (before -jar or class name).
5.5. On 32-bit Windows, it appears as though the IDV
starts up correctly but the Map View is blank (black) and I get this error:
Java3d Warning: Fail to lock Vertex Buffer - D3DERR_DRIVERINTERNALERROR.
First, you will need to switch the Java3D backend from OpenGL to
. If you are using
runIDV.bat to start the IDV, edit that file, uncomment the appropriate line
for Direct-X and add the -Dj3d.d3dVertexProcess=software
option. If you have your own script for starting the
IDV, add in the -Dj3d.rend=d3d -Dj3d.d3dVertexProcess=software
to your start line (before -jar or class name).
5.6. Does the IDV support 3D Stereo?
The Java 3D library which the IDV uses supports stereo on properly
configured stereo devices. We have added
the necessary code to allow stereo to work in certain configurations.
At present, the Unidata Program Center does not have access to a stereo
system like a GeoWall, so our experience testing with these systems
is limited. You will need to modify the runIDV script to change the
starting the IDV.
If your runIDV script does not have the
argument in it then change:
command="java -Xmx512m -jar idv.jar $*"
command="java -Xmx512m -Didv.enableStereo=true -jar idv.jar $*"
After doing this, if you bring up the IDV on a
stereo device and it does not appear to be in stereo, use the
to set the display to a perspective view.
5.7. My stereo display only seems to use one eye of the glasses. How
do I fix this?
Some stereo cards do not keep a separate Z-buffer per eye. If you
are experiencing problems, try changing the line in the runIDV script to:
command="java -Xmx512m -Didv.enableStereo=true -Dj3d.sharedstereozbuffer=true -jar idv.jar $*"
6.1. I get the error "Bad version number in .class file" on my Mac. What does this mean?
IDV 2.8 requires Java 6 and most systems have Java 6 as the default
version. On Mac OS-X, prior to the Snow Leopard release (10.6), Java 5 is
the default version of Java. If you are not running Snow Leopard, you will
need to update your Java version. See the
for information on updating
Java on Mac OS-X.
6.2. How do I connect to remote servers through my firewall?
If you have a firewall and you try to get data from the remote
servers (image, radar, point, upper air and profiler data), you may get error
messages such as "Error opening connection ... Operation timed out"
or "No Data Available." For these servers to send data, your
firewall software must allow connections on ports 112 (ADDE) and 8080
(THREDDS Data Server).
6.3. I get an error that starts something like "Unexpected Signal : 11 occurred at PC=0x6F79CE1" when starting the IDV under Linux. What does this mean?
If the error message also includes a line that is looking for a
Library with "dri" in it's name
(e.g.: Library=/usr/X11R6/lib/modules/dri/i915_dri.so), it means
that you are trying to load the DRI library in your X server which
is not compatible with Java 3D. You need to comment out the line:
in your X server configuration file (xorg.conf or XF86Config).
7.1. What kind of support does Unidata provide for the
Unidata provides support to the entire community of IDV users
through software updates, documentation, discussion email lists,
and searchable support archives.
Unidata provides direct support for the IDV
to institutions offering college-level courses for credit, and to
non-profit institutions with education or research missions.
For more information, see the Unidata Support web page:
7.2. How do I report problems?
First, check this FAQ and the list of Known Problems
to make sure this is a problem that has not yet been reported.
If you experience unexpected behavior from the IDV other than
the known problems, please let us know.
See the Reporting Errors to Unidata Support
section of the manual for the procedures on how to do this.
7.3. How do I open the Error Logs Console?
Open a console to show error logs with the menu.
7.4. What information does the IDV send to Unidata
There are 2 things that Unidata may receive when you run the IDV. First, the IDV can access
a number of resource files from the Unidata web site
Like any web access this is recorded by the web server access logs and no personally identifying
information is recorded beyond the IP address.
When you submit a support request via the IDV information regarding the version of the IDV, the version of
Java and the plugins you have installed is included in the support request.
7.5. The IDV has locked up and is not responding. What do I do?
First, we need to have you retrieve a stack track of the program so we can find out
why this is happening.
If you are running the most recent version of the IDV (after October 15th, 2008) the IDV provides
a web-based service that produces a stack trace. Just view the URL:
and send the results to firstname.lastname@example.org
Note: this service is only available from browsers running on the machine the IDV is running on.
You can also use this service to shutdown the IDV.
If you are running an earlier version of the IDV you can:
On Windows do a control-break key in the IDV terminal window and copy/paste the result.
On Linux/Unix either do a control-/ in the terminal window or do a kill -3 <java process id>
To kill the IDV you can either close the windows or, if that does not work, remove (on Windows) the java.exe process through the Windows Task Manager or by killing the process on Linux/Unix.
At this time we're not sure how to do this on a Mac.
Java on SunOS is particular with its handling or 32 versus 64 bit
architectures. See notes in runIDV script. You will have to add a -d64 JVM
argument as is explained in the runIDV script. Please send question
if you still have concerns.