Frequently Asked Questions

These FAQs provide details about the contents and services offered at NGA-Earth.org.
If you have a question not captured here please contact us.

What types of imagery and maps are available?

The NGA Imagery layer is provided through NGA by Commercial Data Providers, courtesy of DigitalGlobe® and GeoEye® as part of NGA’s ClearView/NextView contracts for commercial imagery.  The imagery is often available in panchromatic (grayscale) and multispectral (color) versions. 

The maps available in the viewer are provided by Microsoft® under agreement with NGA.

Occasionally, NGA is able to make imagery available for specific incidents in response to a direct request from a lead federal agency. The lead federal agency is chartered with the response. Examples would include the Federal Emergency Management Agency (FEMA) and the Department of State.

The specific cases where this has occurred include:

2008:

• Tropical Storm Faye damage to Florida during August 2008. Imagery courtesy of DigitalGlobe® and GeoEye® was approved for public viewing on the site for 30 days beginning 22 August 2008. Available imagery includes pre- event collection where it was available and post- event collection as it was tasked by NGA.
• Flooding in the Midwestern United States (imagery from June 16, 2008 through June 30, 2008)
• Typhoon Damage in Myanmar (imagery from May 1, 2008 through May 25, 2008)

2005:

• Hurricanes Katrina, Wilma and Rita on the Southern United States

How can I look at the imagery and maps?

If you want to take a quick view of the imagery, use the MapApp Viewer.  For certain datasets our viewer is configured to display “footprints” of the imagery when users are zoomed out to very large geographic coverages. 

If you have Google Earth and are used to using that for viewing geospatial data, you should use our KML reflector  to overlay NGA imagery.  If you have an Open Geospatial Consortium Web Map Service (OGC WMS) compliant application, you may also connect to our imagery and map server.  In the example shown here, the blue boxes show the footprints where NGA Imagery is available over areas impacted by the June 2008 flooding in the midwestern United States.

When you see these footprints you can zoom in (using the navigation tools at the bottom of the window, or the mouse wheel to zoom in/out) until eventually the imagery is displayed instead of the footprint.  By rendering footprints at zoom levels where it would be difficult to understand the imagery anyway, we significantly reduce the number of servers required to provide you access to the imagery.  The example here shows the imagery after zooming in sufficiently within the viewer.  (As a tip, you can also blend the imagery with the underlying map by moving the yellow/orange slider left and right next to the “NGA Imagery” layer.  You can turn the NGA imagery layer off by simply unchecking the box.)

Finally, if you need to get specific imagery to meet your mission need, consider using the NCDS system.

How do I know what data is new or recent?

Unfortunately at the moment through the web interfaces provided today you cannot tell the currency of the imagery.  We’ve developed a number of prototype viewers that will expose the temporal metadata from the imagery and hope to be able to provide that information soon.