Witness and Response: September 11 Acquisitions at the Library of Congress
Geography and Map Division

Witness and Response: September 11 Acquisitions at the Library of Congress
Ground Zero Aerial Imagery, September 15, 2001

Ground Zero Aerial Imagery, September 15, 2001. New York State, Office for Technology (Copyright 2001) and EarthData International. Geography and Map Division

In collecting cartographic materials relating to the events of 9/11, the Library's Geography and Map Division is concentrating on documenting the role maps played in managing the recovery effort. Traditional surveying and mapping techniques as well as modern electronic and remote sensing technologies were employed to aid the rescue and recovery operations, including remote sensing and aerial imagery, digital orthophotography, cutting-edge laser (light detection and ranging--LIDAR) technology with the capability of producing accurate elevation data, and thermal imagery for mapping hot spots in the rubble.

These mapping initiatives directed at the federal, state, and municipal levels--sometimes in association with the private-sector--provided important geographic and cartographic resources to help officials evaluate damage, monitor the progress of recovery, and provide for the safe deployment of personnel.

Aerial Views and Maps of the WTC - Thermal Imagery

A thermal sensor flown at 5,000 feet over Ground Zero, provided imagery to track the underground fires that burned for weeks. The hottest areas of the rubble appear in shades of purple. The thermal imagery was overlaid on a map database that shows the footprints of the destroyed buildings in red lines. The standing buildings are indicated by green lines.

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Aerial Views and Maps of the WTC - LIDAR

A laser-based imaging instrument, known as LIDAR (light detection and ranging), provided elevation data of the Ground Zero site. It enabled emergency managers to assess damage through the smoke. The LIDAR data was used to determine changes in the rubble pile and to create 3-D digital elevation models that demonstrated the extent of the destruction.

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    WTC – LIDAR Three Dimensional Model, July 2001. New York State, Office for Technology (c2001) and EarthData International. Geography and Map Division

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    WTC – LIDAR Three Dimensional Model, September 15, 2001. New York State, Office for Technology (c2001) and EarthData International. Geography and Map Division

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    WTC – LIDAR Three Dimensional Model, September 17, 2001. New York State, Office for Technology (c2001) and EarthData International. Geography and Map Division

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    WTC – LIDAR Three Dimensional Model, September 17, 2001. New York State, Office for Technology (c2001) and EarthData International. Geography and Map Division

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Flythrough Visualizations

Two flythrough visualizations are part of this exhibit: the visualization of Lower Manhattan before September 11, 2001 was created for a traveling exhibition entitled Charting Ground Zero: Before and After which originally opened at the Woodward Gallery in New York City, while the visualization of the devastation at the World Trade Center is based on both digital aerial imagery and LIDAR elevation data collected after the September 11 attacks.

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    Flythrough of Lower Manhattan Before September 11, 2001. Courtesy of Woodward Gallery, Dr. Sean Ahearn, Center for the Analysis and Research of Spatial Information (CARSI), Hunter College, and Sanborne Colorado and Co., Inc. Geography and Map Division

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    Flyover of Ground Zero, September 26, 2001. New York State, Office for Technology (c2001) and EarthData International. Geography and Map Division

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Aerial Views and Maps of the WTC - Digital Imagery

Digital aerial imagery was collected daily over the WTC site. Converted to digital orthophotography, the resulting images provided an accurate and up-to-date depiction of the situation at Ground Zero, enabling emergency managers to safely direct equipment and personnel during the rescue and recovery effort.

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