Showing posts with label season. Show all posts
Showing posts with label season. Show all posts

Tuesday, July 24, 2012

Forty years of satellite images of our planet

We are celebrating today the 40th anniversary of the Landsat satellite program . This program is the acquisition of satellite images of Earth with the longest continuous operation. Over the years, Landsat has collected petabytes of images, offering a historical perspective of change that our planet has undergone. This information can help researchers and independent nations, make informed decisions about their economic and environmental policies. In conjunction with the USGS and the Carnegie Mellon University , we are working to make parts of this huge collection of publicly available images form of sequential video (taken at time intervals) from the surface of the Earth . With them can travel through time, from 1999 to 2011 to see the transformation that has taken our planet. Will see changes such as deforestation of the Amazon, urban growth in Las Vegas or the difference between the snow country with the change of season. Below are some examples:


http://i.imgur.com/KSrz8.png 
The sequential scan through the Amazon rain forest shows the spread of deforestation between 1999 (left) and 2011 (right). 

http://i.imgur.com/pEv00.png 
The rapid growth of Las Vegas, Nevada between 1999 (left) and 2011 (right) is visible on Landsat sequential scan. 


http://i.imgur.com/3mhoh.png 
A seasonal sequence created using MODIS images , where each video frame represents one week, shows the differences between areas covered by snow in the U.S. between February and August 2002. 


We believe these are the largest video frames that have been created. If you could see the video in full resolution, a single frame would terapixeles 1.78, ie the equivalent of 18 football fields of screens placed edge to edge. In 2008 the USGS opened access to full Landsat archive for free . Google Earth Engine allows access to this information and makes it useful for scientists and people around the world. In the following video may learn more about the history of the Landsat program and how Google Earth Engine was used to process and analyze this huge archive of satellite images of the planet.



Landsat congratulate these 40 years. We are proud to make this coarse file available to the general public, and for deep analysis of scientists and policymakers around the world. Visit the site Google Earth Engine to experience all the interactive tours through the videos sequentially. By Eric Nguyen, a software engineer for Earth Engine, and Randy Sargent, a visiting researcher at Carnegie Mellon University