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http://www.pobonline.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2338,69244,00.html Posted on: 01/01/2002 Mapping Community Aids Areas in Wake of Terrorism The reality of an America touched by terrorism hit Mike Aslaksen, staff cartographer for the Remote Sensing Division of the National Oceanic and Atmospheric Association’s National Geodetic Survey (NOAA NGS), as he traveled toward Ground Zero shortly after the terrorist attacks of Sept. 11, 2001. “Initially, it was shocking,” Aslaksen said. “I had traveled in that area quite a bit, and when heading north on the turnpike you come over a hill and you see the Center towers. When I didn’t see them, it hit hard.” Fortunately, Aslaksen had the comfort of knowing he could do something to help. He was just one of many people in the surveying and mapping profession who utilized his skills to help support recovery and cleanup efforts at the World Trade Center site in New York and at the Pentagon. The NOAA’s NGS aided efforts in New York and at the Pentagon, beginning on Sept. 15, 2001. NGS field survey personnel provided ground support and calibration expertise for airborne imaging sensors. Aslaksen and his team including Ed Carlson, Jason Woolard and Roy Anderson, established GPS base stations and a calibration site using static and kinematic survey techniques at Liberty State Park in New Jersey, across the Hudson River. Additional support was provided by the NGS CORS program. CORS is a network of continuously operating reference stations coordinated by the NGS that provide GPS carrier phase and code range measurements in support of 3-D positioning activities in the United States. CORS provided continuously operating GPS sites in New York to collect data for the remote sensing missions. The NOAA Cessna Citation II jet mapped Ground Zero using aerial photography and LIDAR technology. Flights began on Sept. 23, 2001, and ended Oct. 15, 2001, each flight lasting about four hours. Initial flights over Ground Zero took place on Sept. 23 and 26, 2001, and were followed by three more missions in order to map the entire area of lower Manhattan. The U.S. Army Joint Precision Strike Demonstration coordinated efforts among NOAA, Optech Incorporated (Toronto, Ontario, Canada) and the University of Florida’s Civil and Coastal Engineering department. According to Don Carswell, president of Optech Incorporated, Optech provided Intelligent Laser Ranging System ILRIS-3D LIDAR technology at Ground Zero and ALTM LIDAR technology for the NOAA jet. Optech was also involved in surveying at the Pentagon. The University of Florida provided ground support to aid in manning GPS receivers and to help Optech process data, according to Mike Sartori, a Florida-licensed surveyor and mapper and a research coordinator for the University of Florida’s ALSM lab. LIDAR data created digital surface models and accurate 3-D models of the building structures as well as the surrounding area. This helped to identify the rubble and its stability so that appropriate cranes could remove it. Data collected by the LIDAR equipment also provided building and utility engineers with information to locate original foundation support structures, elevator shafts and basement storage areas, according to Jon Bailey, chief of the NGS remote sensing division. He said LIDAR equipment helped to monitor the seawall surrounding the base of Manhattan, which was a concern because damage could lead to flooding. NOAA’s jet also took high-resolution photos of Ground Zero, detailing the site and allowing recovery crews to see how far debris fell from it. EarthData International also conducted LIDAR missions over Ground Zero under the direction of the New York State Office for Technology. EarthData, based in Washington, D.C., specializes in airborne imaging, mapping and GIS. “They felt our technology would help to manage Ground Zero,” said Linda Harrington Baker, EarthData’s director of marketing and communications. “Within eight to 12 hours we had figured out a strategy for them and went to Albany in a Navajo Chieftain plane.” EarthData conducted three different assignments for the New York State Office for Technology: Aerial LIDAR missions, digital imagery and thermal imagery. The first of several LIDAR missions began on Sept. 15, 2001, according to Bryan Logan, EarthData CEO. Missions continued daily until Oct. 23, 2001, with the exception of two or three days when poor weather suspended operations. The aerial missions were supported by the NOAA’s NGS base stations. LIDAR information helped to show the depth of the rubble and aided civil engineers in determining the stability of surrounding buildings. Thermal imagery collected by EarthData helped firefighters to detect fires at Ground Zero. Aerial flights ran thermal sensors at dawn in order to avoid false positive readings by ground areas heated in the sun, according to Logan. The imagery showed where fires were and helped firefighters to get a clearer picture of where fires were spreading or receding. Digital orthophotography was taken later in the day. Digital orthophotos helped create accurate maps to overlay upon existing New York city maps to help determine where gas and power lines were located. This helped to re-orient the area for rescue workers and firefighters in their cleanup and recovery efforts. “Digital orthophotos showed pathways through the rubble, and they (rescue and recovery workers) could see they were making strides,” Harrington Baker said. Working at Ground Zero stirred emotions, but Aslaksen said everyone stayed focused on the task at hand to aid those in need.