Peer-Reviewed Article Abstracts
275 Commercial
High-Altitude Unpiloted Aerial Remote Sensing: Some Legal Considerations
Joanne Irene Gabrynowicz
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Since the 1970s, images and data from remote sensing satellites have been collected
and used in commercial applications ranging from crop management to mineral
exploration. Aerial remote sensing goes back even further. However, it was
not until recently that breakthroughs in workstation and software technology
catalyzed a surge in commercial remote sensing applications and experimentation.
The increased ability to manipulate and mix different kinds of data has,
in turn, spawned an interest in finding innovative data gathering platforms.
One in particular, High-Altitude Unpiloted Aerial Vehicles (HAUAVs), has
become the recent subject of inquiries as to its value for commmercial remote
sensing. This paper addresses some general legal issues raised by using this
particular technology in a commercial remote sensing business that collects,
processes, and sells data and imagery.
279 The Open Skies
Treaty: Qualitative Utility Evaluations of Aircraft Reconnaissance and Commercial
Satellite Imagery
Matthew Heric, Carroll Lucas, and Christopher Devine
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The International Open Skies Treaty provides for the independent collection
of aircraft imagery, in addition to commercially available satellite data,
over selected arms and weapons facilities. This paper compares the joint
and relative utility of commercially available satellite data and aircraft
imagery in an analysis of information content for Open Skies Treaty monitoring
requirements. Thematic Mapper Simulator (TMS), Thermal Infrared Multispectral
Scanner (TIMS), and APD- 10 radar data were used to simulate a range of spatial
resolutions and to determine the utility of each data set. A qualitative
analysis of the simulated aircraft imagery, at progressively improved resolutions,
revealed an exponential increase in treaty-specific information content starting
with 10-m resolution.
285 Film Cameras or
Digital Sensors? The Challenge Ahead for Aerial Imaging
Donald L. Light
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Cartographic aerial cameras continue to play the key role in producing quality
products for the aerial photography business, and specifically for the National
Aerial Photography Program (NAPP). One NAPP photograph taken with cameras
capable of 39 l p/mm system resolution can contain the equivalent of 432
million pixels at 11 mu m spot size, and the cost is less than $75 per photograph
to scan and output the pixels on a magnetic storage medium. On the digital
side, solid state charge coupled device linear and area arrays can yield
quality resolution (7 to 12 mu m detector size) and a broader dynamic range.
If linear arrays are to compete with film cameras, they will require precise
attitude and positioning of the aircraft so that the lines of pixels can
be unscrambled and put into a suitable homogeneous scene that is acceptable
to an interpreter. Area arrays need to be much larger than currently available
to image scenes competitive in size with film cameras. Analysis of the relative
advantages and disadvantages of the two systems show that the analog approach
is more economical at present.
293 The Evaluation
of MEOSS Airborne Three-Line Scanner Imagery: Processing Chain and Results
C. Heipke, W Korn us, and A. Pfannestein
Abstract
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A completely digital processing chain realized for the evaluation of airborne
three-line scanner imagery acquired by the Monocular Electro-Optical Stereo
Scanner (MEOSS) is described. It involves image matching, photogrammetric
point determination, and the generation of a digital terrain model (DTM).
The computations were carried out using image data from one flight path and
from two crossing paths, with and without navigation data as additional observations
for the exterior orientation parameters. The derived results were checked
using independent measurements from medium- scale aerial frame imagery. Whereas
the navigation data turned out to be essential for the processing of one
flight path, they were not necessary for the simultaneous processing of both
paths. Subsequently, a DTM was derived from up to six rays per object point,
thus reducing the effect of gross errors inherent in image matching. The
DTM represents the visible Earth's surface, including houses, vegetation,
etc., rather than being a 'bare earth DTM,' which is usually derived from
interactive measurements.
301 Methods for Computing
Photogrammetric Refraction Corrections for Vertical and Oblique Photographs
Maurice S. Gyer
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Photogrammetric refraction computation methods for high oblique aerial photographs
are derived from Snell's law for rays in a spherically stratified atmosphere.
The methods, based on numerically integrating the refraction integrals, are
applicable for zenith angles between 0 and 90 degrees. The atmospheric index
of refraction is determined from atmospheric models of pressure and temperature.
The models may be adjusted to reflect local pressure and temperature data
when available. Standard aircraft pressurization procedures are used to evaluate
the pressurized camera compartment refraction. Expressions are derived for
the corrections to the image coordinates of photographs with arbitrary obliquity.
The effects of different atmospheric models, geographic location, time of
year, and large zenith angles are illustrated in the form of numerical tables
and graphs. The results are applicable to determining the ground coordinates
of points imaged with high oblique aerial surveillance cameras. A byproduct
of the theory is a unified treatment of atmospheric refraction for arbitrary
zenith angles.
311 Floating Lines
and Cones for Use as a GPS Mission Planning Aid
Michel Boulianne, Rock Santerre, Paul-André Gagnon, and Clement
Nolette
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This paper presents a new method for generating obstruction diagrams as a function
of site obstacles for GPS observations. The proposed method takes advantage
of the human ability for stereoscopic vision. Instead of going on the site
and measuring the azimuth and elevation angle of every obstacle in the vicinity
of a prospective GPS point, the photogrammetric approach proposes using a
visibility cone injected into a stereoscopic model. In this way, the time
consuming and costly phase of site reconnaissance is eliminated. In the presence
of obstructions, the cone rays that are lower than the obstacles are raised
like floating lines. Afterwards, by recording the azimuth and elevation angles
of these rays, obstruction contours can be generated. With this diagram,
superimposed on the satellite track plot, the mission planner can evaluate
the best GPS observation window based, for example, on Geometric Dilution
of Precision (GDOP). A practical test shows the applicability and feasibility
of the method.
317 Forest Canopy,
Terrain, and Distance Effects on Global Positioning System Point Accuracy
Christopher Deckert and Paul V Bolstad
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Tests were conducted to determine the realizable accuracies of the Global Positioning
System under eastern North American forest conditions. The effects of terrain,
forest canopy, number of consecutive position fixes, and PDOP on accuracy
were evaluated. Position accuracies were determined for a total of 27 sites:
three replicate sites selected for all combinations of three canopy (deciduous,
conifer, open) and three terrain (ridge, slope, valley) types. The mean differentially
corrected positional accuracy for all sites was 4.35 metres, with 95% of
the mean positions estimated within 10.2 metres of the true value. The least
accurate differential position data were observed at conifer sites. Positional
accuracy was higher for deciduous sites and highest at open sites. Mean positional
accuracy increased from valley to ridge locations.
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