Peer Reviewed Articles
589 Emerging Legal and Ethical Issues in Advanced Remote Sensing
Technology
E. Terrence Slonecker, Denice M. Shaw, and Thomas M. Lillesand
Abstract
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Fundamental changes are taking place in the world of remote
sensing with respect to three primary developments.
First, a new generation of space-borne sensors will be able to
deliver high spatial and spectral resolution imagery on a
global basis. Technical advances are making previous restrictions
on data scale, resolution, location, and availability
largely irrelevant. Second, economic restructuring of the remote
sensing community will transform the control and
distribution of imagery and imagery-derived information generally
away from government and into the private sector.
Third, the development of a digital, global information infrastructure,
such as the Internet. will allow for rapid global
distribution of information to a worldwide user community.
The combined effects of these developments could have significant
legal and ethical consequences for all remote sensing
professionals. For example, remote sensing technology
could soon develop the capability to generate and deliver a
level of information detail that could violate common societal
perceptions of individual privacy. and a number of direct
legal and ethical consequences could result.
This paper reviews the legal background of remote sensing
and current developments in satellite surveillance and
information technology, and outlines a number of legal and
ethical issues that could be of future concern to the remote
sensing community. Self regulation of the profession is central
to maintaining the appropriate balance between the
rights of the individual and the economic interests of the remote
sensing community and the nation as a whole.
597 Bias and Precision of Different Sampling Methods for GPS Positions
Michel Arnaud and Albert Flori
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Based on GPS readings taken four mornings running, this article
uses statistical methods, taking account of observation
dependence, to study bias and variance of errors. It is shown
that with or without filtering based on criteria such as the
number of satellites or PDOP, mean longitude and latitude
values are unbiased. In the experiment carried out, filtering
was used to improve the precision of longitude readings, but
had a lesser effect on latitude. However, filtering can cause
long delays before obtaining a reading. Replicating readings
can increase their precision, provided certain operating conditions
are respected.
601 Mosaicking Airborne Scanner Data with the Multiquadric Rectification
Technique
Kenneth C. McGwire
Abstract
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A new multiquadric image rectification technique is shown
to provide superior results for mosaicking nine flight lines of
airborne scanner data covering 200 km² of hilly terrain with
limited ground control. The multiquadric technique provided
excellent edge matching and less than half the absolute geometric
error of polynomial-based techniques.
607 Satellite Monitoring of Lake Ice Breakup on the Laurentian Shield
(1980-1994)
Randolph H. Wynne, Thomas M. Lillesand, Murray K. Clayton, and John J.
Magnuson
Abstract
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Lake ice breakup dates from 1980 to 1994 for 81 selected
lakes and reservoirs in the U.S. upper Midwest and portions
of Canada (6O°N, 105°W to 40°N, 85°W) were determined employing
analysis of 1,830 archival images from the visible
band (0.54 to 0.70µm) of the GOES-VISSR.The objectives
were to investigate the utility of monitoring ice phenology as
a climate indicator and to assess regional trends in lake ice
breakup dates. The dates of imagery represented the range
available in the national archive at the time of this study.
Comparison of satellite-derived breakup dates with available
ground reference data revealed a mean absolute difference of±3.2 days and a mean difference of -0.4 days, well within
the natural variability in lake ice breakup dates ( σ ≈ 12
days) for a single lake over time. The predominant spatial
trends of mean ice breakup dates can be attributed to latitude
and snowfall (R² = 93 percent). Analysis of the pooled
data for all 81 lakes revealed a significant (p < 0.001) trend
toward earlier ice breakup dates. All of the individual lakes
exhibiting significant trends toward earlier ice breakup from
1980 to 1994 are located in southern Wisconsin.
619 Accuracy Assessment of a Land-Cover Map of the Kuparuk River Basin,
Alaska: Considerations for Remote Regions
S.V. Muller, D.A. Walker, F.E. Nelson, N.A. Auerback, J.G. Bockheim. S.
Guyer, and D. Sherba
Abstract
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An accuracy assessment of e Landsat MSS-derived land-cover
map of the Kuparuk River basin, Alaska was preformed. We
used a stratified systematic transect-based sampling design
with a homogeneous 3- by 3-pixel block sampling unit. The
ramifications of the sampling strategy are discussed. Sample
sites were located using a helicopter and a Y-Code GPS receiver.
Estimates of overall classification accuracy (P), Tau
(Te), producer's accuracy, and user's accuracy were calculated
from an error matrix. Assessment methods based on
fuzzy sets theory was used to supplement the error matrix.
The accuracy estimates indicate a classification with high
accuracy. However, they are likely to have a fair degree of
optimistic bias and can only be applied reliably to homogeneous
3 by 3 blocks of pixels. The combined use of an error
matrix and fuzzy sets allowed for a more precise analysis of
errors. Based on this analysis, changes were made to the final
map. Several methodological advantages contributed to
the high classification accuracy.
629 Map-Guided Approach for the Automatic Detection on Landsat TM
Images of Forest Stands Damaged by the Spruce Budworm
Stéphane Chalifoux, François Cavayas, and James T. Gray
Abstract
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A map-guided approach was followed in order to identify
forest stands damaged by the spruce budworm on Landsat
TM images. Pixels included in each forest polygon as indicated
on the map are extracted and their values in TM4 and
TM5 spectral bands, transformed to reflectance units, are analyzed
using a set of numeric rules. These rules are based on
the frequencies of occurrence of pixel values in pre-defined
intervals. The change-detection/identification accuracy varies
according to the stand type. Thus, for coniferous stands with
defoliation and/or light mortality, the accuracy was 95 percent
whereas, for mixed stands, an accuracy lower than 80
percent was obtained. These results indicate that the proposed
method behaves well as a fast detection technique in a
complex forest environment. It has a definite advantage over
all standard methods, by permitting the characterization as
damaged or not of an entire stand, instead of the individual
image pixel. Ways to further improve its performance, especially
in the case of mixed stands, are also discussed.
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