NASA will apply its image-processing expertise to
enhance underground radar images of the area around the World
Trade Center in New York, providing a clearer picture of
what’s beneath the surface.

“Our image-processing techniques will provide the first
enhanced subsurface images of the area around ‘ground zero,'”
said Dr. Amir Fijany, principal scientist and supervisor for
the Ultracomputing Technology Research Group at NASA’s Jet
Propulsion Laboratory (JPL), Pasadena, Calif. “Our goal is to
pinpoint utility lines and improve the overall sharpness of
the images.”

Witten Technologies, Inc., of Boston, will supply JPL with
underground images from lower Manhattan created with ground-
penetrating imaging radar in surveys done for Consolidated
Edison Company of New York, Inc. (Con Edison) in August 2001
and January 2002.

Witten used a new technique called underground “radar
tomography,” which resembles satellite radar but rides on the
back of a truck directly over the site, producing a 3-D
picture of what’s below the surface to depths of about 1.8
meters (6 feet). Those images have already proved valuable in
helping reduce the amount of digging needed to maintain dense
underground utility networks.

JPL would add another dimension to the images already
collected by Witten by pinpointing linear features such as
gas and electrical utility lines. “We have a continuous
underground image below about 8 acres of streets in lower
Manhattan, including several streets surveyed before and
after 9/11,” said Michael Oristaglio, chief scientist of
Witten Technologies. “But some of the most important features
are fuzzy; they’re at the limit of resolution of the radar.
We are hoping that JPL’s expertise in advanced radar-image
analysis can bring these features into sharp focus.”

This partnership is possible through JPL’s Technology
Affiliates Program that allows large and small businesses to
work with JPL technologists. It is one of several JPL
technology transfer programs designed to bring the benefits
of the space program to American industry.

Witten is providing JPL with data from around the World Trade
Center area before and after September 11. “Comparing these
two sets of radar images taken from the same area at two
different times may enable the team to detect underground
changes and assess the extent of damage,” said Fijany.

JPL will apply its image-processing and feature-extraction
techniques to these images. The primary goal will be to
pinpoint semi-continuous linear features that could
correspond to buried utility lines such as phone lines, gas
lines, pipes or other infrastructure. A secondary goal is to
improve the overall sharpness and appearance of the raw image
by reducing clutter and enhancing linear features. This
initial phase is expected to take six months.

Additionally, JPL will conduct tests on three other sets of
images with increasing level of complexity from other sites
in Manhattan taken in February and July 2001.

JPL has been conducting remote sensing and image processing
of Earth and other planets for more than four decades. Fijany
led a similar assignment in subsurface imaging to detect
unexploded ordnance for the U.S. Army Corps of Engineers.
During this assignment, radar data collected by high-altitude
airborne ground-penetrating synthetic aperture radar was used
for subsurface imaging. Advanced image-processing techniques
were then applied to the radar images.

The results from that work showed this type of remote sensing
technology could detect very small features below the
surface. Similar subsurface imaging technology will be
applied to the images collected by Witten to enhance their
overall quality.

The California Institute of Technology in Pasadena manages