NSIDC Virtual Globes: Technical Experiments

This page lists some of our experiments with using Google Earth to visualize our data. These files illustrate capabilities we are interested in developing, as technology progresses. Each resulting file proves some capabilities, but also has limitations, as discussed below. These technical notes may be of interest to other Google Earth file developers.

See also

Movie of sea ice extents, 1979-2008, on Google Earth (QuickTime, 1.6 MB)

NSIDC Data on Virtual Globes: Google Earth

Atlas of the Cryosphere

Related resources

NSIDC Virtual Globes Help and Documentation

Questions, comments or suggestions? Contact us at nsidc@nsidc.org.

KML Files
Technical Notes
Source Data
Visualization of ICESat Shots in Google Earth (VISGE) over Anchorage AK
(KML, 4 KB)

Technical Notes: The Geosciences Laser Altimetry System (GLAS) takes 40 measurements per second, or about 240,000 measurements per orbit. At 14 orbits per day with campaigns lasting up to 30 days, the sheer quantity of measurements makes the display of GLAS data in a virtual globe a fairly challenging task. This experiment, named the Visualization of ICESat Shots in Google Earth (VISGE), seeks ways to make massive numbers of point measurements available in a virtual globe without overloading the system.

For a 5x5 degree area around Anchorage, Alaska USA, NSIDC has created subsampled files for each campaign, allowing users to visualize the coverage of the orbits. The full data is only loaded once the user has zoomed in to a sufficiently small area. For each campaign, NSIDC has created 2500 0.1x0.1 degree bins. Each bin file contains up to 3500 placemarks representing a GLAS footprint and providing access to the waveform image for that measurement.

For more information on this project, see the Visualization of ICESat Shots in Google Earth (VISGE) Overview Web page. In order to aid in the future development of this tool, please share your feedback on the usability of this interface by taking the VISGE Usability and Feature Request Survey.

GLA06 Product
MODIS Mosaic of Antarctica
(KML, 4 KB)

Technical Notes: MOA provides a cloud-free view of the ice sheet, ice shelves, and land surfaces at a grid scale of 750 m and 125 m with an estimated resolution that ranges between 150 m and 250 m, depending on the number of images that were stacked and how the images were weighted. All land areas south of 60° S that are larger than a few hundred meters are included in the mosaic. Also included are several persistent fast ice areas and grounded icebergs.

The data for the MODIS Mosaic of Antarctica 2003-2004 (MOA2004) Image Map were acquired from November 2003 through February 2004. The data for the The MODIS Mosaic of Antarctica 2008-2009 (MOA2009) Image Map were acquired from November 2008 to February 2009.

The KML file accesses the MOA2004 Map Server interface to display each of seven available contrast stretches in addition to the RAMP image mosaic. See the Map Server User's Guide.

MODIS Mosaic of Antarctica 2003-2004 (MOA2004)

MODIS Mosaic of Antarctica 2008-2009 (MOA2009)

NSIDC Field Data File for Google Earth
(KML, 3 KB)

This file includes data from anywhere on the globe for which the spatial coverage is adequately described by a one-degree bounding box, representing data from a single point.

Technical Notes: This approach was a way of exploring how to most easily create a Google Earth file for our field data. We add such data sets to our catalog frequently, so coming up with a rule for identifying these data sets and adding them to the file would make it possible to somewhat automate maintenance of such a file. The resulting file is only a very limited part of our extensive data collection.

Various data sets; links for each data set are included with each pushpin.
Screen Overlays Example File (KML, 9 KB) Screen Overlays

This file includes examples of how to use screen overlays in Google Earth. No actual data or imagery is presented

Technical Notes: Screen overlays are images placed on the screen to display ancillary information that puts the other information in context. Things like logos, titles, and legends are often displayed as screen overlays. See Virtual Globes: KML Screen Overlays for more information.