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Generalized Stochastic Subdivision
 ACM Transactions on Graphics
, 1987
"... This paper describes the basis for techniques such as stochastic subdivision in the theory of random processes and estimation theory. The popular stochastic subdivision construction is then generalized to provide control of the autocorrelation and spectral properties of the synthesized random functi ..."
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This paper describes the basis for techniques such as stochastic subdivision in the theory of random processes and estimation theory. The popular stochastic subdivision construction is then generalized to provide control of the autocorrelation and spectral properties of the synthesized random functions. The generalized construction is suitable for generating a variety of perceptually distinct highquality random functions, including those with nonfractal spectra and directional or oscillatory characteristics. It is argued that a spectral modeling approach provides a more powerful and somewhat more intuitive perceptual characterization of random processes than does the fractal model. Synthetic textures and terrains are presented as a means of visually evaluating the generalized subdivision technique. Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image Generation; I.3.7 [Computer Graphics]: Three Dimensional Graphics and Realism <F11.
Mixing in turbulent jets: scalar measures and isosurface geometry
 J. Fluid Mech
, 1996
"... Experiments have been conducted to investigate mixing and the geometry of scalar isosurfaces in turbulent jets. Specifically, we have obtained highresolution, highsignaltonoiseratio images of the jetfluid concentration in the far field of round, liquidphase, turbulent jets, in the Reynolds num ..."
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Cited by 11 (3 self)
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Experiments have been conducted to investigate mixing and the geometry of scalar isosurfaces in turbulent jets. Specifically, we have obtained highresolution, highsignaltonoiseratio images of the jetfluid concentration in the far field of round, liquidphase, turbulent jets, in the Reynolds number range 4.5 x lo3 < Re < 18 x lo3, using laserinducedfluorescence imaging techniques. Analysis of these data indicates that this Reynoldsnumber range spans a mixing transition in the far field of turbulent jets. This is manifested in the probabilitydensity function of the scalar field, as well as in measures of the scalar isosurfaces. Classical as well as fractal measures of these isosurfaces have been computed, from small to large spatial scales, and are found to be functions of both scalar threshold and Reynolds number. The coverage of level sets of jetfluid concentration in the twodimensional images is found to possess a scaledependentfractal dimension that increases continuously with increasing scale, from near unity, at the smallest scales, to 2, at the largest scales. The geometry of the scalar isosurfaces is, therefore, more complex than powerlaw fractal, exhibiting an increasing complexity with increasing scale. This behaviour necessitates a scaledependent generalization of powerlawfractal geometry. A connection between scaledependentfractal geometry and the distribution of scales is established and used to compute the distribution of spatial scales in the flow. 1.
A model of error for choropleth maps, with applications to geographic information systems
 Proceedings, AutoCarto 8
, 1987
"... The precision of geographic information systems is in sharp contrast to the accuracy of much spatial data, and requires a more objective approach than is conventional in cartography. Existing models of the error of cartographic lines are inappropriate for topological data for various reasons. We pro ..."
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The precision of geographic information systems is in sharp contrast to the accuracy of much spatial data, and requires a more objective approach than is conventional in cartography. Existing models of the error of cartographic lines are inappropriate for topological data for various reasons. We propose a model of error in choropleth data, with specific application to the data types found in natural resource inventories. One or more spatially autocorrelated continuous vari ables are generated, and mapped through a number of domains into a choropleth map with nominal attributes. Fractional Brownian surfaces are convenient sources of the continuous variables. The choropleth boundaries are subject to additional smoothing. Although the model is probably too complex to calibrate, it can be used to simulate choropleth images under a wide range of conditions, in order to investigate effects of error and accuracy in a variety of GIS func tions.
Multiscale Terrain Analysis of Multibeam Bathymetry Data for Habitat Mapping on the Continental Slope
 Mar. Geodes
"... Multibeam surveys can provide detailed bathymetry data for the continental slope from which quantitative descriptors of the seabed terrain (e.g., slope) may be obtained. We illustrate the value of these descriptors for benthic habitat mapping, and highlight the advantages of multiscale analysis. We ..."
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Multibeam surveys can provide detailed bathymetry data for the continental slope from which quantitative descriptors of the seabed terrain (e.g., slope) may be obtained. We illustrate the value of these descriptors for benthic habitat mapping, and highlight the advantages of multiscale analysis. We examine the application of these descriptors as predictor variables for species distribution models, which are particularly valuable in the deep sea where opportunities to directly survey the benthic fauna remain limited. Our initial models are encouraging and suggest that wider adoption of these methods may assist the delivery of ecologically relevant information to marine resource managers.
N.: Extraction of surface properties from a high accuracy DEM using multiscale remote sensing techniques
 In: Proc. of the 19th Conf. Informatics for Environmental Protection
, 2005
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The rush to publish
 Science
, 1991
"... can be found at:Progress in Physical GeographyAdditional services and information for ..."
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can be found at:Progress in Physical GeographyAdditional services and information for
Effects of spatial and spectral resolutions on fractal dimensions in forested landscapes. Remote Sens
"... Abstract: Recent work has shown that more research is needed in applying fractal analysis to multiresolution remote sensing data for landscape characterization. The purpose of this study was to closely examine the impacts that spatial and spectral resolutions have on fractal dimensions using realw ..."
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Abstract: Recent work has shown that more research is needed in applying fractal analysis to multiresolution remote sensing data for landscape characterization. The purpose of this study was to closely examine the impacts that spatial and spectral resolutions have on fractal dimensions using realworld multiresolution remotely sensed data as opposed to the more conventional single resolution and aggregation approach. The study focused on fractal analysis of forested landscapes in the southeastern United States and Central America. Initially, the effects of spatial resolution on the computed fractal dimensions were examined using data from three instruments with different spatial resolutions. Based on the criteria of mean value and variation within the accepted ranges of fractal dimensions, it was determined that 30m Landsat TM data were best able to capture the complexity of a forested landscape in Central America compared to 4m IKONOS data and 250m MODIS data. Also, among the spectral bands of Landsat TM images of four national forests in the southeastern United States, tests showed that the spatial indices of fractal dimensions are much more distinguishable in the visible bands than they are in the nearmid infrared bands. Thus, based solely on the fractal analysis, the fractal dimensions could have relatively
Fractal interrelationships between topography and structure
 Earth Surf. Processes Landforms
, 1998
"... Abstract—Regional and local characteristics of active fault patterns and elevation variation throughout Honshu, Japan are characterized in terms of their fractal dimensions; this allows variation in these complex variables to be compared directly to the scalar properties of net Quaternary vertical d ..."
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Abstract—Regional and local characteristics of active fault patterns and elevation variation throughout Honshu, Japan are characterized in terms of their fractal dimensions; this allows variation in these complex variables to be compared directly to the scalar properties of net Quaternary vertical displacement, elevation and 10 and 110year horizontal strains. The comparisons reveal that, throughout Honshu as a whole, there is significant correlation (hri 0:75) between Quaternary vertical displacement, elevation, and its fractal properties. There is poor correlation, however, of elevation and its fractal properties to horizontal crustal strain, and also between Quaternary vertical displacement and horizontal crustal strain. A slight negative correlation is observed between the fractal properties of the active fault system and horizontal crustal strain measured over 10and 110year time periods ()0.43 and)0.26, respectively). The correlation between the 10year (1985– 1994) and 110year (1883–1994) area strains, 0.48, reveals the occurrence of considerable change in the distribution of regional strain over these short time frames. Local computations of the correlation between data sets made for overlapping 160 km length windows of data spaced every 20 km along analysis lines reveal internal fluctuations in the correlation between variables. The local correlation between Quaternary vertical displacement and elevation is highest through
A Science of Topography: Bridging the QualitativeQuantitative Divide
"... The shape of the Earth's surface, its topography, is a fundamental dimension of the environment, shaping or mediating many other environmental flows or functions. But there is a major divergence in the way that topography is conceptualized in different domains. Topographic cartographers, inf ..."
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The shape of the Earth's surface, its topography, is a fundamental dimension of the environment, shaping or mediating many other environmental flows or functions. But there is a major divergence in the way that topography is conceptualized in different domains. Topographic cartographers, information scientists, geomorphologists and environmental modelers typically conceptualize topographic variability as a continuous field of elevations or as some discrete approximation to such a field. Pilots, explorers, anthropologists, ecologists, hikers, and archeologists, on the other hand, typically conceptualize this same variability in terms of hills and valleys, mountains and plains, barrows and trenches, that is, as (special sorts of) objects, with locations, shapes, and often names of their own. In this chapter, we sketch an approach to bridging this fundamental gap in geographic information infrastructure.
A method for detecting objects using Legendre transform
 in RFAI team publication, Maghrebian Conference on Computer Science MCSEAI, Annaba (Algeria
, 2002
"... Dans cet article nous allons présenter une méthode de détection d’objets basée sur l’analyse multifractale. La détection d’objets est particulièrement difficile lorsque l’on ne connaît pas les caractéristiques des objets pouvant être présents dans l’image. Contrairement aux méthodes le plus souvent ..."
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Dans cet article nous allons présenter une méthode de détection d’objets basée sur l’analyse multifractale. La détection d’objets est particulièrement difficile lorsque l’on ne connaît pas les caractéristiques des objets pouvant être présents dans l’image. Contrairement aux méthodes le plus souvent proposées, cette méthode est destinée à détecter des objets artificiels dans des images photographiques prises depuis le sol. Cette méthode peut trouver des applications dans le domaine de la robotique en evironnement inconnu ou hostile. Parmi de nombreux exemples d’applications potentielles, on peut imaginer d’utiliser cette méthode pour trouver des détritus sur une plage. Cette méthode est basée sur un calcul de spectre multifractal en utilisant la transformée de Legendre. Elle tire profit de la capacité du spectre multifractal de Legendre d’opérer une discrimination entre les textures. La méthode d’analyse d’image consiste à diviser l’image en imagettes et à calculer le spectre multifractal de Legendre de chaque imagette en utilisant une approche par comptage de rectangles. Des critères de détection sont ensuite évalués pour déterminer la position des objets, en se basant sur le fait que le spectre multifractal de Legendre a une forme différente selon la texture. La méthode utilisée pour le calcul du spectre multifractal de Legendre sera présentée dans cet article, ainsi que son application pour la détection d’objets, et enfin on interprétera les résultats expérimentaux. Motsclé: Reconnaissance d’objet, spectre multifractal, transformée de Legendre, détection d’objet, groupement et segmentation