Peer-Reviewed Articles
1245 An Automated Method for Digitizing Color Thematic Maps
Rick L. Lawrence, Joseph E. Means, and William J. Ripple
Abstract
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There is an increasing need for methods of rapidly entering analog data into
geographic information systems. Traditional methods of hand digitizing or
hand tracing followed by scanning are costly and time consuming. The authors
have developed a rapid, easy to use method for digitizing color thematic
maps that makes use of standard image processing techniques. The method uses
a digital camera followed by supervised spectral classification and post-
classification smoothing. Although overall accuracy for an extremely challenging
test map was 93%, results indicate that for most applications expected accuracy
is very high.
1249 Mapping Ecological Land Systems and Classification Uncertainties
from Digital Elevation and Forest-Cover Data Using Neural Networks
P. Gong, R. Pu,and J. Chen
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Emphasizes mainly the technical aspects of the land-systems classification
problem with neural networks. Using digital elevation, its derivatives, and
forest cover data as input, the authors constructed neural networks to classify
27 land- system classes at Duck Mountain, Manitoba, Canada. Training and
testing of those neural networks were done using an existing land-systems
map prepared through airphoto interpretation and field studies. Two types
of data structure were evaluated: polygon and raster forms. Types of data
sets contained the elevation, slope, aspect, dominant forest species and
corresponding crown closures, and more general site information on cover
type, subtype, site, cutting class, and crown closure. Results indicate that
a random sampling strategy for training sample selection led to better classification
results than a contiguous sampling method. Approximately 10% of the total
samples were sufficient for network training. The best overall classification
accuracy was 52.0% when the neural network classification result was compared
with the existing map.
1261 Spatial and Compositional Pattern of Alpine Treeline, Glacier
National Park, Montana
Thomas R. Allen and Stephen J. Walsh
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Quantifies the complex patterns of alpine treeline across an extensive area
of Glacier National Park, Montana. Satellite image classification, digital
terrain modeling, and GIS measurements of landscape structure provided important
tools for the analysis. The study area was topographically partitioned into
watersheds and hillslope units in which to measure treeline patterns. Cluster
analysis of selected spatial and compositional pattern metrics was used to
infer major alpine treeline forms. Six significant treeline types were differentiated
using patch richness, contagion, contrast, number of patches, fractal dimension,
relative edge density, and forest-tundra juxtaposition. Clusters were validated
using split-sample replication and discriminant analysis. Patterns were found
to differ among types of terrain, affirming hypothesized sensitivities to topoclimatic
gradients, natural disturbances, and geologic substrate.
1269 Predicting Rare Orchid (Small Whorled Pogonia) Habitat Using
GIS
Molly B. Sperduto and Russell G. Congalton
Abstract
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Iostria medeoloides (Pursh) Raf., commonly known as the small whorled pogonia,
is the rarest orchid in eastern North America, north of Florida. A geographical
information system (GIS) was used to facilitate locating potential habitat
for Isotria medeoloides in New Hampshire and Maine. Two predictive GIS overlay
models were developed: an equal weight model and a chi-square model. As a
result of the chi-square evaluation, the following general characteristics
were determined to be positively associated with small whorled pogonia sites:
soils with a pan layer, percent slopes between 11 and 17%, and a digital
reflectance greater than 68 for the near infra-red band of Landsat Thematic
Mapper data. Nine previously undiscovered populations of Isotria medeoloides were found. The GIS provided a useful tool for combining ecological habitat
characteristics to successfully predict potential habitat for Isotria
medeoloides.
1281 Application of a Modified Habitat Suitability Index Model for
Moose
Jeffrey A. Hepinstall, LLoyd P. Queen, and Peter
A. Jordan
Abstract
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This paper explores alternative approaches for calculating moose Habitat Suitability
Index (HSI) values using a GIS. We modified an existing moose HSI model and
implemented it using moving windows and various boundary value estimation methods.
The habitat window and boundary analyses indicate that a 50% window overlap
is sufficient to capture variation in the landscape. A mirror data set for
areas outside the study area, used to estimate boundary habitat values from
a sample grid within a vector GIS, is proposed as a useful alternative for
supporting landscape-scale resource management.
1287 Using Genetic Learning Neural Networks for Spatial Decision Making
in GIS
Jiang Zhou and Daniel L. Civco
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Traditional approaches for suitability analysis in GIS are overlay and the
more complicated multicriteria evaluation (MCE). Despite being widely used,
these methods have at least three problems: difficulties in handling spatial
data possessing inaccuracy; multiple measurement scales, and factor interdependency;
requirements of prior knowledge in identifying criteria, assigning scores,
determining criteria preference, and selecting aggregation functions; and typically,
an 'unfriendly' user interface. To solve these problems, in this paper a neural
network approach is presented. The neural network uses a genetic algorithm
as its learning mechanism. A set of experiments revealed that the aforementioned
difficulties are overcome by the evolutionary learning of neural networks.
Genetic learning neural networks can provide an alternative for and improvement
over traditional suitability analysis methods in GIS.
1297 Extending the Applicability of Viewsheds in Landscape Planning
Peter F. Fisher
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The determination of the visible area or viewshed from a viewing point looking
out on a landscape is a widely available function in a GIS. A reconsideration
of the queries which may be made of the viewshed, however, revals that often
the function does not address them correctly. This has led to the specification
of alternative viewshed functions intended to give flexible outcomes which
can be used to respond to the queries directly. The alternatives include the
horizons viewshed, the local offset viewshed, the global offset viewshed, and
reverse viewing versions of all three. Applications of these alternative viewshed
functions to answer queries about the landscape and the view which the binary
viewshed is not able to respond to either precisely or flexibly are examined.
1303 A Comprehensive Managed Areas Spatial Database for the Conterminous
United States
R. Gavin McGhie, Joseph Scepan,and John E.
Estes
Abstract
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The compilation of a comprehensive, spatially referenced, digital database
of managed areas in the conterminous United States is described. As concern
over ecosystem degradation increases, so does the need for accurate, up-to-date
information on the spatial location and aerial extent of currently managed
and protected areas. This need represents the fundamental motivation for creation
of this Managed Areas Database (MAD). MAD includes information on the level
of protection each management designation provides, sources used for compilation,
and a number of additional attributes. MAD can be used with supplementary data
sets for conservation planning, and to determine protection status. The authors
believe that this database can and will support a wide variety of environmental
studies.