Researchers have brought photonics technology to bear on the sites of the Sept. 11 terrorist attacks in New York and Washington. A team at the University of Florida in Gainesville is imaging the buildings surrounding the World Trade Center in New York to assess the structural damage using airborne laser-swath mapping and ground-based scanning laser systems. In related work, a team from the National Oceanic and Atmospheric Administration's National Geodetic Survey in Silver Spring, Md., and its Aircraft Operations Center at MacDill Air Force Base in Florida has employed aerial lidar to map both sites.The National Science Foundation has awarded the university team a $45,000 grant to perform the survey. The researchers will study the maps they have constructed, such as the one above, to determine if the walls of the surrounding structures are vertical and if there are signs of bulging.The NOAA researchers outfitted a Citation jet with a lidar system from Optech Inc. of Toronto to produce maps with a relative accuracy of 0.3 m. The maps will be used in cleanup and recovery efforts to locate support structures and utility connections and to determine the risk of flooding. The US Army's Topological Engineering Center in Alexandria, Va., coordinated the project, and the University of Florida and Optech assisted in the work.