stereo photogrammetry stereo photogrammetry - BAE Systems GXP ...

Reprinted from
© Earth Imaging Journal
March/April 2005
The International Air Transport Association
is updating major international airport
maps that don’t conform to current
standards. Here an IKONOS satellite image
of Madeira, Portugal, illustrates a typical
training scenario. The red line indicates the
optimal flight path that a pilot would use
to avoid hitting any obstacles.
Stereo Photogram
Making 21st Century
Air Transportation Safer
Techniques rooted in the 1950s form the
basis for modern airport analysis.
By Carolyn Gordon, BAE Systems (www.socetgxp.com),
San Diego, and Dejan Damjanovic, Space Imaging
(www.spaceimaging.com), Denver.
On April 3, 1996, in Dubrovnik, Croatia, a plane crash
resulted in the deaths of U.S. Secretary of Commerce
Ronald H. Brown and 33 other passengers and crew.
The deadly accident was attributed to poor weather
conditions, a lack of knowledge of the airfield environment
and an off-course approach. As a result of the tragedy, Congress
passed the Ron Brown Airfield Initiative in 2000 to improve
airfield navigation information. Since then, using conventional
land surveying techniques and modern digital photogrammetry,
many airport operators are taking advantage of today’s geospatial
and satellite sensor technology to ensure safer flight paths.
Arrival and departure paths to and from airports must be kept
free of significant man-made and natural obstacles, including trees,
buildings and other features. The Federal Aviation Administration
(FAA) defines the formal requirements in the United States, as does
the International Civil Aviation Organization (ICAO) for the rest
of the world. In each case, the regulations define a virtual polygon
centered around the ends of the runway, as well as a series
of ever-larger polygons that must be kept free of any obstacle
that an airplane could hit when flying in that space.
As shown in the image at the top of page 38, these virtual
polygons, or “surfaces,” are defined in 3-D space sloping up
from the end and sides of each runway until reaching the edge
of the surface. There are different surfaces for take-off, landing,
landing on nonprecision instruments, landing on precision
instruments and day/night operations. Prior to the Global
Positioning System (GPS) satellite constellation, information
regarding obstacles in the vicinity of each airport could only
be collected by extensive ground survey, with some degree of
validation possible with conventional stereo photogrammetry.
© 2005 Earthwide Communications LLC, www.eijournal.com