Marine Data Literacy 2.0

Providing instruction for managing, converting, analyzing and displaying oceanographic station data, marine meteorological data, GIS-compatible marine and coastal data or model simulations, and mapped remote sensing imagery





Home > 9. Operational/Synoptic > 9.1 IDV Setup

9.1 Integrated Data Viewer (IDV) Preliminary Setup

  • Exercise Title:  Integrated Data Viewer (IDV) Preliminary Setup

  • Abstract:  IDV is the most ambitious multi-format data visualization platform for metocean data available today.  Although not at all limited to OPeNDAP-based data resources, it is clearly oriented strongly in that direction, due both to the common source (UNIDATA), and to the extreme popularity of that protocol in the US environmental mainstream.  IDV operations require the user to learn the use of a "dashboard" control feature whereby datasets are selected and display options are specified, more elaborate than the "properties" controls found in GIS systems.  In this exercise, IDV is installed and some basic settings are implemented for later use with actual datasets.

  • Preliminary Reading (in OceanTeacher, unless otherwise indicated):

  • Required Software:

    • Integrated Data Viewer - The native version (direct from UNIDATA) is recommended.  There is, however, a "GEON version" which is extended with enhancements related to solid earth data, and improved data-import functions.

    • - Zipped shapefile of the Liberia graticule; IDV can display shapes, but usually only if they are zipped

  • Other Resources: 

    • N/A

  • Author:  Murray Brown and Mihael de Souza

  • Version:  January 2014

1.  Install and run IDV.  When the process is complete, you should see a DOS COMMAND window, and at least one open program display window named UNIDATA IDV - Map View - One Pane
2.  Download the zipped Liberia graticule (above) to the folder PRODUCTS > SAGA > VECTORS
3.  This is the main mapping window of IDV.
4.  In the upper left corner, find the DASHBOARD icon and click it.  The dashboard is the principal controls set for the display of the data objects.

[The dashboard may already be open.  Or, you may have to click the dashboard icon more than once to activate it.]

5.  On the dashboard, select EDIT > PREFERENCES
6.  On the page tabbed GENERAL, you should start with these settings.  Make sure that you do check the item SHOW DASHBOARD ON START.


7.  On the page tabbed VIEW, uncheck the option SHOW EARTH NAVIGATION PANEL.

Now you can click OK to apply these preferences.

8.  To get the default map you see in Panel 3, above select EDIT > PREFERENCES > VIEW > DEFAULT PROJECTION > WORLD.
9.  Return to the dashboard window.  Notice that the main view panel and the dashboard have the same command line options, a very unusual situation among all the major software systems.  It takes a while to get used to this, but it makes a lot of the functions easier to find.
10.  On the dashboard, click on DATA CHOOSERS.
11.  For DATA SOURCE TYPE select SHAPEFILE.  Then navigate to PRODUCTS > DATA > VECTORS and select

Then click on ADD SOURCE at the bottom of the screen.

12.  Click on the FIELD SELECTOR tab to see these options.  Then simply click on the CREATE DISPLAY control.

NOTE:  Latest version of IDV says "MAP DISPLAY" instead of "SHAPEFILE DISPLAY"

13.  This graticule is drawn on the main map window.

Now, just for future use, we're going to draw a box around this graticule and name it as one of IDV's "projections".  This will always let you get back to viewing the Liberia area, if perhaps you have navigated away from it by accident.

15.  This is the projections editing page.  Click on NEW.
16.  This global map opens, to let you manually choose a region for a new projection.
17.  Name the new projection "Liberia", and draw the box corners into the approximate area of Liberia.

Then click SAVE.

18.  You'll see this smaller map of your new projection area.

Click on OK.

19.  Now select the new projection with PROJECTIONS > PREDEFINED > LIBERIA
20.  Now you can see how closely you came to the desired target region.

Use the PROJECTIONS > NEW/EDIT to move the sides in and out to your satisfaction.  It will take several repeats to get it right.

21.  This is approximately how the final edit will look, although a smaller margin would be nicer.
22.  After mid-2011, when this exercise was first written, many IDV users have asked for exact control of the box coordinates (rather than the rubber-band method above).  This was particularly requested to help with export problems to Google Earth, and IDV's automatic "projection" setting (see below).  In the next few steps, which are completely optional, you can see how to do that.  In any even, you will need the LIBERIA projection (approximate or exact) to control the globe area you are visualizing in IDV.
23.  Specially added projections, such as LIBERIA above, are kept in the file PROJECTIONS.XML located in your home directory.  For most users, this is:
  • My Computer > C:\ > Documents and Settings > [user name] > .unidata > idv > DefaultIdv
24.  Find the file PROJECTIONS.XML and make a safety copy of it in the same folder.
25.  Open the file in any good ASCII editor.  There will be at least one "method".

Each method extends from a <method name-"add"> tag to a </method> tag.  Between these tags are the essential information defining the projection.

Here you can see the LIBERIA section highlighted.


26.  Near the center are these 4 lines, defining the LEFT, BOTTOM, RIGHT and TOP of the box.  There is a separate line defining the CENTER LONGITUDE (above the other 4 lines).



27.  For our exact Liberia area of interest, we'd need to insert these values:
  • LEFT = -23
  • BOTTOM = -6
  • RIGHT = -3
  • TOP = 9

It is uncertain in the IDV documentation if the center longitude is critical, but we'll edit it also.

28.  Here you can see the changes
29.  Simply save the ASCII XML file back its original location.  Then close and re-open IDV to make the changes.
30.  Here is the world map again.
31.  Before you do anything else, notice that there is an AUTO-SET PROJECTION control.  This causes many problems in IDV to new users.  Whenever you make a new map, this default returns, even if it has been turned off before.  It appears to work smoothly with the user, but behind the scenes it sometimes stores faulty box coordinates in memory, so that exported Google Earth images are incorrectly georeferenced.

If you ever have problems with Google Earth exports from IDV, then do this:

  • Select PROJECTIONS > PREDEFINED > LIBERIA.  This removes possible errors caused by the AUTO-SET function.
32.  The map reduces to this area of interest.  Notice that the coastline segment is much shorter than in Panel 21 above.  So our new area limits must have taken effect.
33.  And here we've added the graticule.  It fits exactly over the projection frame.
34.  NOTE:  The projection frame is of great importance in IDV, because you need complete control over the displayed area.  In view of the information in Panel 31, above, we recommend that you always apply your preferred projection ("Liberia" in this case), even if a new dataset appears to be mapped correctly.  We know from experience that the AUTO-SET function can be lurking in the background and screwing up your exported image data products.

35.  It's time to take a look at the complete IDV desktop to see how the map we've made has been labeled.

36.  This is the legend in the lower left corner.  If any item had a color palette, it would also be shown here.

NOTE:  This legend is apparently permanent and the author has not found a way to turn it off.

37.  And this is the legend in the upper right corner.  If any item had a color palette, it would also be shown here.

NOTE:  This legend can be turned on or off with VIEW > DISPLAYS > HIDE or EMBED (referring to the VIEW item just above and to the left of the map)

38.  Both of these legends, as they refer to the graticule, need editing to provide better information to readers/scientists.  In the panels that follow, we'll use Mihael de Souza's methods to clean them up.
39.  Select the graticule object in the right-side menu and this dashboard opens.
40.  Select EDIT > PROPERTIES.
41.  This properties window opens.  Here you can find how IDV has created the LEGEND LABEL.

You can see that the graticule was named by adding together these 2 items:

  • %shortname% - The filename itself
  • %displayname% - The name of the type of map IDV drew for the object.  In Panel 12 above, you can see that this was either "Map Display" or the older term "Shape Display".  We can see that for ourselves, so we don't really need it now.
42.  Change the LEGEND LABEL to read something easily understood, as you see here.  Then click OK.
43.  And the legend is now easier to understand, both in the top right location and in the bottom left location.

NOTE 1: On your own, you should explore all of the many DISPLAY and VIEW options in IDV to get your maps to say everything you want them to.  This short lesson only scratches the surface.

Note 2:  You need to make the above adjustments in the LEGEND LABEL for all data maps that you intend to publish or include in presentations.  The method is always the same, so it's included here in the setup instructions for your use later, as needed.

44.  Now you're ready to begin working in IDV.  This program is extremely powerful and complex, so you should expect to spend weeks working with it before you feel comfortable.  Unfortunately the exercises which follow are very short and direct, so if you want to get full use from IDV, you must take your own time later.