Thursday, January 31, 2013

Thoughts on post-event damage detection

Thanks to an AmericaView mini-grant and the labor of some intrepid students we were able to do a detailed damage assessment of some of the areas in Vermont hardest hit by Hurricane Irene back in 2011.  The pre-event imagery was sourced from the National Agricultural Imagery Program and we obtained post-event WorldView-2 imagery from the USGS Hazard Data Distribution System (HDDS).  Below are some key take-away points for this type of work.

  • It's all about the resolution.  As much as I love Landsat you really need high-resolution imagery, such as WorldView2, to see the type of damage causes by an Irene-type event.
  • Manual image interpretation.  While we would like to think that all we need is imagery from two different dates and a press of the Staples Easy Button to get results, the reality is much more complex.  This is particularly true in post-event disaster response.  Automated detection may help highlight areas of change, but chances are you will have to do it the old way to precisely quantify the damage.  No one beats a human when it comes to high-resolution image analysis.
  • Georegistration is a challenge.  Much of the imagery that was acquired post-Irene was done so at rather extreme look angles.  Orthorectificaton did not yield promising results and it was time consuming.  Thus, all the damage mapping was done on the more accurate pre-event imagery through good old fashioned terrain association.  The offset is shown quite clearly in the above graphic.
  • Come up with a damage class domain.  Lots of interpreters may be working on the same project and thus it really helps if you can come up with a list of damage types so that all of the datasets are consistent.
  • Work locally.  The cloud and networks tend not to fare too well during disasters.  Digitizing goes a heck of a lot faster when the imagery is stored locally.

Hazard Data Distribution System (HDDS) tutorial

Geospatial data, particularly imagery, are crucial during disaster response.  The USGS has a wonderful web-based application called the Hazard Data Distribution System (HDDS) that provides the capability to download incident related imagery.  This video provides a short overview of HDDS, demonstrating how to you can use HDDS to locate and download imagery for your area of interest.  Please note that if you are involved in disaster response you will need to request permissions from the USGS to obtain access to the licensed imagery.  For more info on  HDDS please read the help pages.

Tuesday, January 29, 2013

Land Remote Sensing: Now for the iPad

Landspotting (, a recently released game for the iPad, allows players to characterize the landscape into simple and general land cover types (e.g. Urban, Trees, Grass, Water, Snow and Ice, Unknown, etc.) using their fingers to paint on high resolution satellite imagery. It is a tower-defense-game whereby players earn coins to buy new buildings, more warriors, and resources. The better the player paints, the more houses added to your village and the more warriors you have to protect against invaders.
However, the underlying goal of this game is crowd-sourcing the validation of global land cover types in order to improve global satellite-based land cover maps and products. The game was developed in cooperation with the project ( The game can be downloaded from iTunes.

Thursday, January 24, 2013

Host a LDCM / Landsat 8 Launch Party!

Earth’s land cover is changing at an increasingly rapid rate, and these changes have dramatic impacts on our lives whether we know about them or not.  Scientists use a variety of instruments to observe and quantify the changes in an ongoing attempt to better understand their ramifications on society, and on the ecosystems upon which we all depend.

Dating back to 1972 and free to the public, the Landsat series of Earth observing satellites offers the longest and most comprehensive data set of the Earth’s surface from space. The future of the program, the Landsat Data Continuity Mission (LDCM), is a collaboration between NASA and the U.S. Geological Survey (USGS) and is ready to take the next big step.  On February 11th, 2013, Landsat 8 is scheduled to launch from Vandenberg Air Force base in California aboard an Atlas V rocket. To learn more about the LDCM, NASA has developed a video available here.

NASA and the USGS have been working on the LDCM for years. To celebrate the LDCM and raise awareness of the many benefits of this increasingly important civilian land imaging satellite, the Landsat Education and Public Outreach Team has put together a website of materials that people at universities, museums, community centers, or anywhere could use to hold their own launch party. They invite us all to participate in this exciting and historic milestone in humanity's efforts to make our Earth more livable and sustainable. You can join others around the world in celebration of this much-anticipated event by hosting a launch party! Planning and hosting your own launch party with NASA resources is fun and easy, and it's a wonderful way to engage your community in your interests and the work you do.

Everything you need to host a great party and join in the launch fun is at your fingertips, right here.

You will find activities and decorations to make your party fun for all ages. You'll be able to watch the launch and associated events live, including talks from NASA and USGS scientists and engineers.

Enjoy the celebration of the LDCM, and please pass this information on to others.