Peer-Reviewed Article Abstracts
155 Recomputation of the Global Mars Control-Point Network
W. Zeitler, T. Ohlhof, and H. Ebner
Abstract
Download
Full Article
This paper deals with the recomputation of the global control point
network of the planet Mars. The existing Mars control point net is
based on Viking data and consists of a large number of ground points,
which can be easily identified in the imagery and whose three-dimensional
(3D) object coordinates (e.g., latitude, longitude, and height with
respect to a reference ellipsoid) are known. These coordinates were
redetermined in order to eliminate several disadvantages of the former
computations and to include the currently best available input data
such as improved Viking trajectory information, the Viking occultation
data, present rotational parameters, and the Mars Pathfinder lander
data. Within a simultaneous 3D bundle block triangulation, seven
interior orientation parameters, the position and attitude parameters
of 1140 images, and the ground coordinates of 3739 tie points and
one control point were estimated. The RMS values uX, uY, uZ
of the theoretical standard deviations of the adjusted object coordinates
amount to 750 m, 770 m, and 710 m, respectively, which is a significant
improvement compared with former results (1 to 5 km). The accuracy
of the ground point coordinates is close to the theoretical accuracy
limit of 520 m in X, Y, and Z, where error-free orientation parameters
are assumed. This new set of orientation parameters and ground points
may now be used for local, regional, and global DTM generation; for
the determination of reference bodies; for mapping purposes; as well
as for current (Mars Global Surveyor 1996) and future (e.g., Mars
Surveyor 1998 and 2001, Mars Express 2003) missions to Mars.
163 Continuous Piecewise Geometric Rectification for Airborne
Multispectral
Scanner Imagery
Minhe Ji and John R. Jensen
Abstract
Download
Full Article
Geometric rectification of airborne multispectral scanner image data using
traditional polynomial functions often cannot provide satisfactory RMSE accuracy
due to the complex nature of geometric distortions in the data. The discrete
approach to rectifying these data generates segmented pieces that may cause
edge-matching problems after they are reassembled. To improve the rectification
accuracy while retaining the continuity of the rectified strip, a continuous
piecewise geometric rectification approach is introduced. Using logical divisions
of a strip and the concept of overlapping area anchor ground control points,
the approach localizes the complex distortion and greatly improves the edge-match
between pieces. A description of the procedure is presented along with two
case studies, each having a different set of sensor and terrain characteristics,
to illustrate the advantages of this approach versus traditional techniques.
173 A Standardized Radiometric Normalization Method for Change Detection
Using Remotely Sensed Imagery
Joon Heo and Thomas W. FitzHugh
Abstract
Download
Full Article
The image normalization process aims to remove radiometric differences between
multitemporal images that are due to non surface factors. Accurate normalization
is essential for image processing procedures that use multi-date imagery,
such as change detection. Linear regression using temporally invariant targets
is a widely accepted method for normalization. However, except for the criteria
for selecting target points, there is no standard method for conducting this
important procedure. This paper proposes a standardized radiometric normalization
method for detecting and deleting outliers and obtaining the optimal linear
equation for a given set of target points. The method consists of a linear
regression model and a studentized residual method for outlier determination.
Standardized decision criteria such as R2 and confidence range for t-test
are discussed and investigated, as are the issues of band selection and normalization
target size. Four variants of the method are tested here, using a pair of
Landsat TM images 10 years apart and corresponding training sets and accuracy
assessment data. As a result, a standardized computation procedure is proposed,
which uses band-by-band linear regression, single pixel targets, and a very
conservative 99 percent confidence interval for determining outliers.
183 Estimation
of Canopy-Average Surface-Specific Leaf Area
Using Landsat TM Data
Leo Lymburner, Paul J. Beggs, and Carol R. Jacobson
Abstract
Download
Full Article
Specific leaf area (SLA) is an important ecological variable because of its
links with plant ecophysiology and leaf biochemistry. Variations in SLA are
associated with variations in leaf optical properties, and these changes
in leaf optical properties have been found to result in changes in canopy
reflectance. This paper utilizes these changes to explore the potential of
estimating SLA using Landsat TM data. Fourteen sites with varying vegetation
were sampled on the Lambert Peninsula in Ku-ring-gai Chase National Park
to the north of Sydney, Australia. A sampling strategy that facilitated the
calculation of canopy-average surface SLA (SLACS) was developed. The relationship
between SLACS, reflectance in Landsat TM bands, and a number of vegetation
indices, were explored using univariate regression. The observed relationships
between SLACS and canopy reflectance are also discussed in terms of trends
observed in a pre-existing leaf optical properties dataset (LOPEX 93).
Field data indicate that there is a strong correlation between SLACS and
red, near-infrared, and the second mid infrared bands of Landsat TM data.
A strong correlation between SLACS and the following vegetation indices:
Soil and Atmosphere Resistant Vegetation Index (SARVI2), Normalized Difference
Vegetation Index (NDVI), and Ratio Vegetation Index (RVI), suggests that
these vegetation indices could be used to estimate SLACS using Landsat TM
data.
193 Radiation-Vegetation Relationships in Eucalyptus Forest
Lalit Kumar and Andrew K. Skidmore
Abstract
Download
Full Article
Radiation-vegetation relationships for 12 species of Eucalyptus from the south
coast of New South Wales showed that the mean radiation values differed significantly
between species. Confidence intervals around the mean radiation values, based
on pooled standard deviation, were used as an index of species generality.
There were differences in the size of the confidence intervals between species.
While E. bosistoana and E. maidenii had large confidence
intervals over all seasons, E. sieberi, E. muellerana, and E.
globoidea had very small confidence intervals. The species also exhibit
a shift in the relative positions of their confidence intervals according
to season. Clearly, radiation data are an important variable for eucalypt
species delineation, and may be included as an explanatory variable when
modeling the distribution of eucalypts. Solar radiation was calculated for
the different seasons of the year using a model developed within a geographic
information system (GIS); the input to the model is simply a digital elevation
model (DEM) and the latitude of the site.
205 Detecting Wetland
Change: A Rule-Based Approach Using NWI and
SPOT-XS Data
Paula F. Houhoulis and William K. Michener
Abstract
Download
Full Article
Spectral similarities among wetlands and agricultural fields and forests can
create difficulties in satellite image classification. Utilizing ancillary
information, such as National Wetlands Inventory (NWI) data available from
the U.S. Fish and Wildlife Service, to define wetlands provides a practical
solution to this problem. However, NWI data are at least a decade old for
many areas. In this study, data derived from SPOT-XS imagery were used to
create a rule-based model to detect wetland change and update NWI data. First,
the pixel vector modulus was calculated (sqrt(b21 + b22 + b23/N)), and a
coarse land-cover layer was developed from SPOT-XS imagery. Second,
combinations of the mean modulus value, the majority land-cover value, and
the NWI system class for each polygon were used to develop logic rules to
indicate areas of potential wetland change. Logic rules and change-detection
accuracy varied according to wetland type. At least 8 percent of the wetlands
in the study area had undergone land-cover change since the mid-1980s; however,
most such wetlands were small (<1 ha).
213 Quantification of Chlorophyll in Reservoirs of the Little Washita
River Watershed Using Airborne Video
M.M. Avard, F.R. Schiebe, and J.H. Everitt
Abstract
Download
Full Article
Airborne video cameras equipped with narrow-band filters were used to assess
chlorophyll-a concentration in flood control reservoirs of the Little Washita
River Watershed in central Oklahoma. This study utilizes airborne video cameras
equipped with narrow 10-nm band filters centered at the critical wavelengths
to assess chlorophyll-a concentration.The video cameras were calibrated using
a series of panels and a hand-held spectroradiometer to convert digital numbers
into radiance values (?W/cm2/sr). This was then processed into reflectance
values by the incorporation of solar irradiance data. Results indicate that
the relationship between emergent radiance and chlorophyll concentration
is best described by the model y = a0(1 - e-x/c), and that the ability to
estimate chlorophyll-a concentration in reservoirs using airborne video imagery
has a great deal of potential.
| Top | Home |