The images above show data from NASA's MODIS instrument, received and processed at the University of South Florida's Institute f

The images above show data from NASA's MODIS instrument, received and processed at the University of South Florida's Institute for Marine Remote Sensing (IMaRS). In the color scheme in the images, red normally indicates dry land, while blue indicates water. The top image shows the same area before Katrina hit, showing red throughout New Orleans, meaning dry land. The second image was captured on August 31, 2005, showing large areas of New Orleans and the adjacent Gulf Coast inundated with water. Credit: NASA/USF/IMaRS