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
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.
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
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.
Flythrough of Lower
Before September 11, 2001 [still image]
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
before September 11th [video]
Flyover of Ground
September 26, 2001 [still image]
New York State, Office for Technology
Geography and Map
after September 11th [video]
|The videos are presented in RealPlayer format.
To view them, you must have the Real Player installed and
at least a 14.4 K-bps (kilobits per second)
Internet connection for your computer. The RealPlayer software
may be downloaded, free of charge,
the RealNetwork Web site.
Aerial Views and Maps of the WTC - Digital
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.