PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
August 2017
527
By Craig Molander and John Boeding (CP, PLS), Surdex Corporation
breaking the over 100 year record by three feet. This was
preceded by a crest of 31.48’ on December 19, 2015 – es-
sentially exhibiting two nearly “100-year” floods within a
16-month period. The Meramec Caverns attraction was
again closed for a period of time, along with several camp-
grounds, boat access areas, etc.
Aerial Image Acquisition
Platform and Sensors
For the Meramec River effort, one of Surdex’s Leica ADS100
large-format pushbroom sensors was used to acquire the
imagery. This sensor simultaneously acquires 4-bands of
imagery (red, green, blue, near-infrared) from nadir, for-
ward-looking, and aft-looking arrays. Pixels in each array are
at full resolution, avoiding artifacting from pan-sharpening
and providing optimal stereoscopic geometry. The push-
broom nature of the sensor provides a maximum amount of
near-nadir aspect down the center of each strip, reducing the
seamline effort and avoiding much of the building lean and
elevated structure issues. In addition, the 20,000 pixel width
(at nadir) reduces the number of swaths required to acquire
large areas, optimizing acquisition times to address narrow
windows afforded by the weather. The Meramec imagery was
acquired at approximately 12,500’ AGL (Above Ground Level)
to achieve a resolution of 1’ (~30cm). Precision ABGPS and
IMU data was acquired to both reconstruct the pushbroom
imagery and to provide absolute position and orientation.
The ADS100 was hosted by one of Surdex’s Cessna 441
(Conquest) aircraft. This twin-turbine aircraft is capable
of operating at up to 37,000’ and is equipped with RVSM
(Reduced Vertical Separation Module) and precision radar to
operate above 28,000’ in airliner airspaces. It can cruise at
speeds above 300 knots with an endurance of over 7 hours on
a single tank of fuel. The Conquests are ideal for quickly fer-
rying at night to projects anywhere within the United States
to acquire imagery under ideal atmospheric conditions.
Leica ADS100 installed in a Surdex Conquest aircraft.
One of Surdex’s four Conquest aircraft.
Photogrammetric Engineering & Remote Sensing
Vol. 83, No. 8, August 2017, pp. 526–532.
0099-1112/17/526–532
© 2017 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.83.8.526
