substantially help co-registration of different image
channels too. The introduction of INS systems has had a
dramatic impact on the overall performance of the
georeferencing process. INS systems work with a much
higher data acquisition rate, typically two orders higher
than GPS, providing position and attitude data
simultaneously and almost continuously. These high-
precision integrated GPS/INS systems have been
studied extensively in the academic community
recently, and they are believed to be ready to enter the
commercial production market, see (Lithopoulos ef al.,
1996).
2. AIRBORNE INTEGRATED MAPPING
SYSTEM
The Center for Mapping at The Ohio State University
has developed a GSP/INS integrated positioning system
to support the primarily digital sensor-based image data
collection for the Airborne Integrated Mapping System
(AIMS™). The AIMS™ project goal is to acquire
position and orientation of an aerial platform with
accuracy of 4-7 centimeters and below 10 arcsec,
respectively, over long baselines, which will eliminate
the need for the ground control. The orientation and
positioning accuracies should allow post-processing of
digital imagery to extract feature coordinates at
submeter accuracy, see (Bossler and Schmidley, 1997).
Navigation
Solution —
Optimal Position,
Velocity and
Attitude
Estimates
Rover GPS | Tightly
Control Signal
EO Data
HosuSlave
Communication
Figure 1. AIMS™ conceptual architecture.
The overview of AIMS™, as shown in Figure 1, is a
hardware and software integration of GPS, INS, and
digital imaging technologies in a mobile platform. The
flexible AIMS™ architecture enables the augmentation
of a variety of sensors beyond the high-resolution CCD.
cameras, including infrared cameras, radar, or laser
ranging devices. AIMS™ currently operates in a post-
processing mode, although the ultimate goal is to build
a real- or near real-time system.
The AIMS™ modular architecture will allow
component replacement as technology evolves,
resulting in increased performance without affecting
basic system design. State-of-the-art technology,
especially rapidly advancing processor and storage
technology, can be introduced incrementally into the
system, as it becomes available. The prototype system
has been designed to employ commercial off-the-shelf
products to ensure the most cost-effective
implementation, provided this does not compromise
system performance.
Main Power
Switch
aan aR
j
4 HOVAC
Figure 2. AIMS™ hardware structure.
The main hardware components (Figure 2) currently
employed in AIMS™ are two dual-frequency Trimble
4000SSI GPS receivers, a medium-accuracy and high-
reliability strapdown Litton LN-100 inertial navigation
system, and a 4,096 by 4,096 BigShot™/ Hasselblad
CCD camera. The LN-100 internal software was
modified to provide raw IMU measurements, e.g., the
velocity and angular rates measured by accelerometers
and gyros in the IMU coordinate system. The GPS/INS
data processing is based on a tight integration model,
see (Grejner-Brzezinska, 1997 and Toth, 1997). Besides
these sensors, generic high-end Pentium PCs equipped
with a few special interface boards and running
Windows NT provide the normal computer platform for
the data acquisition and processing tasks.
3. AIMS™ IMAGING COMPONENT
The heart of the AIMS™ High-Resolution Digital
Camera System is a 4K by 4K area CCD sensor with
15-micron pitch (i.e., 60 mm by 60 mm imaging area),
manufactured by Lockheed Martin Fairchild
Semiconductors. The imaging sensor with a supporting
data acquisition interface is integrated into a camera-
back, called BigShot™, mechanically compatible with
an analog film magazine and thus, easily attachable to
regular Hasselblad camera body; see Figure 3.
The Hasselblad 553 ELX camera body features an
electronic control system providing the necessary
apparatus for a fully digital — computer-controlled —
camera operation. Zeiss CF lenses with 50 and 80 mm
focal lengths supplement the experimental camera
system, offering wide and normal angle configurations.
Building the 4K by 4K AIMS™ digital camera and data
48 Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
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