Peer-Reviewed Articles
423 Automated Photogrammetric Network Design Using
Genetic Algorithms
Gustavo Olague
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This work describes the use of genetic algorithms for automating
the photogrammetric network design process. When planning a photogrammetric
network, the cameras should be placed in order to satisfy a set of
interrelated and competing constraints. Furthermore, when the object
is three-dimensional, a combinatorial problem occurs. Genetic algorithms
are stochastic optimization techniques, which have proved useful
for solving computationally difficult problems with high combinatorial
aspects. A system based on genetic algorithms, EPOCA (Evolving POsitions
of CAmeras), was implemented using a three-dimensional CAD interface.
The system provides the attitude of each camera in the network, taking
into account the imaging geometry, as well as several major constraints
such as visibility, convergence angle, and workspace constraint.
EPOCA reproduces configurations reported in the photogrammetric literature.
Moreover, the system can design networks for several adjoining planes
and complex objects, opening interesting new research avenues.
433 Towards Automating the Selection of Ground
Control Points in Radarsat Images Using a Topographic Database and
Vector-Based Data Matching
I. Couloigner, K.P.B. Thomson, Y. Bédard, B. Moulin, E. LeBlanc,
C. Djima, C. Latouche, and N. Spicher
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Users of Radarsat images need ground control points (GCPs) to
georeference their images, to rectify them, and to fuse these images.
Because the selection
of GCPs is usually done manually, the efficiency of the process depends on
the ability of the operator to select a GCP. The present paper introduces
a new method to automatically identify GCPs in Radarsat images using a topographic
database. First, different strategies are elaborated to fit different contexts
(topography, cost, availability of data, etc.). These strategies are then
grouped in two approaches, i.e., vector-based data matching and raster-based
data matching. Both approaches rely on matching feature classes (in ISO/TC211
parlance), e.g., matching "water bodies'' or matching "roads intersections''
from the image with their equivalent on the topographic database. A user
of this method can easily follow the various steps of the GCPs selection
process with the support of software tools. This paper presents in detail
the method developed to select GCPs with the feature class "water body''
and the vector-based matching approach, and also presents some applications.
441 Automated Procedures with Coded Targets in
Industrial Vision Metrology
Susumu Hattori, Keiichi Akimoto, Clive Fraser, and Harutaka Imoto
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In industrial photogrammetric measurement with CCD cameras, the number
of target images may amount to several hundred when large and complex objects
are involved. It is therefore impractical to use solely manual means to identify
these image points. This paper reports on a further design for coded targets,
which can be automatically located and identified, and also discusses special
arrangements of reference targets called exterior orientation devices. These
can be employed in conjunction with new computational schemes for sensor
orientation to facilitate automated data processing. Procedures adopted to
ensure sufficient speed and reliability in automated off-line digital photogrammetric
measurements employing these developments, which have been found in practice
to reduce data processing time by as much as 93 percent, are discussed and
experimental results are reported.
447 Integration of GPS with Remote Sensing and
GIS: Reality and Prospect
Jay Gao
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The advent of the Global Positioning System (GPS) technology has not
only enhanced the ease and versatility of spatial data acquisition, but has
also diversified the approaches by which it is integrated with remote sensing
and geographic information systems (GISs). In this paper the necessity of
integrating GPS, remote sensing, and GIS is discussed following their definition.
The current status of integration is reviewed under four proposed models:
linear, interactive, hierarchical, and complex. Applications of integration
are reviewed under three categories: resources management and environmental
monitoring, emergency response, and mobile mapping. This paper reveals that
linear integration is the most common. Hierarchical integration has found
applications in precision farming and environmental modeling. The complex
mode of integration is most valuable in diaster mitigation, emergency response,
and mobile mapping. With limited cases in hierarchical and complex models,
the full potential of integration has not been achieved. The prospects of
integration are distributed mobile GISs and location-aware multi-media digital
personal assistants. As mobile communications technologies improve, full
integration will find more applications in many new fields after removal
of the obstacles in integration.
455 Modeling the Potential Distribution of Forests
with a GIS
A.M. Felicísimo, E. Francés, J.M. Fernández, A. González-Diez,
and J. Varas
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One of the objectives of forestry planning is to set out criteria for
a territory's reforestation oriented towards the reduction of fragmentation
and the conservation of biodiversity. This objective may be attained by establishing
for each forest type appropriate suitability models, which express the suitability
of each point of the territory for the growth of each forest formation. The
suitability models may be constructed by utilizing spatial analysis methods,
which relate the current presence/absence of forest type to a set of environmental
variables. On the basis of maps of diverse environmental variables, we elaborated
suitability models for the forests present in the study area using logistic
regression and weights-of-evidence techniques integrated into a geographic
information system. Combining the suitability models for each forest type
using simple comparison operators allowed us to construct a potential vegetation
map to use as an objective orientation to the forestry potential of the territory.
463 Spatial and Temporal Analysis of a Tidal Floodplain
Landscape-Amapá, Brazil- Using Geographic Information
Systems and Remote Sensing
Valeria F.G. Pereira, Russell G. Congalton, and Daniel J. Zarin
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For at least 12,000 years, Amazonian floodplains (va;aarzea) have been
exploited by human populations. Although they represent a small fraction
of the Amazon basin, floodplains contain the most productive ecosystems of
the region. Easy access and the abundance of valuable forest products have
historically led to higher human population densities and higher resource
use than in many interfluvial areas. Recent research has brought attention
to land-use and land-cover change in upland Amazonian forests, but relatively
little research has been conducted on similar dynamics in the floodplains.
In this project, we used photointerpretation of 1970s aerial photographs and digital image classification of Landsat Thematic Mapper (TM) 5 imagery from the 1990s to produce land-cover maps used for change detection analysis. A study area in the tidal floodplains of the State of Amapá, in the northern Brazilian Amazon, was evaluated. The accuracy of the Landsat TM classification and errors inherent to the techniques used were assessed. Several changes in the study site were observed, including increases in the areal extent of secondary growth and palm forests and corresponding decreases in intact várzea forest area.
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