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212
Extracting topographic structure from digital elevation data for geographic information system analysis. Photogrammetric Engineering and Remote
 Sensing
, 1988
"... ABSTRACT: Software tools have been developed at the U.S. Geological Survey’s EROS Data Center to extract topographic structure and to delineate watersheds and overland flow paths from digital elevation models. The tools are special purpose FORTRAN programs interfaced with generalpurpose raster and ..."
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Cited by 227 (0 self)
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ABSTRACT: Software tools have been developed at the U.S. Geological Survey’s EROS Data Center to extract topographic structure and to delineate watersheds and overland flow paths from digital elevation models. The tools are special purpose FORTRAN programs interfaced with generalpurpose raster and vector spatial analysis and relational data base management packages. The first phase of analysis is a conditioning phase that generates three data sets: the original DEM with depressions filled, a data set indicating the flow direction for each cell, and a flow accumulation data set in which each cell receives a value equal to the number of cells that drain to it. The original DEM and these three derivative data sets can then be processed in a variety of ways to optionally delineate drainage networks, overland paths, watersheds for userspecified locations, subwatersheds for the major tributaries of a drainage network, or pour point linkages between watersheds. The computergenerated drainage lines and watershed polygons and the pour point linkage information can be transferred to vectorbased geographic information systems for further analysis. Comparisons between these computer generated features and their manually delineated counterparts generally show close agreement, indicating that these software tools will save analyst time spent in manual interpretation and digitizing.
A New Method For The Determination Of Flow Directions And Upslope Areas In Grid Digital Elevation Models
 Water Resources Research
, 1997
"... A new procedure for the representation of flow directions and calculation of upslope areas using rectangular grid digital elevation models is presented. The procedure is based on representing flow direction as a single angle taken as the steepest downwards slope on the eight triangular facets center ..."
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Cited by 148 (2 self)
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A new procedure for the representation of flow directions and calculation of upslope areas using rectangular grid digital elevation models is presented. The procedure is based on representing flow direction as a single angle taken as the steepest downwards slope on the eight triangular facets centered at each grid point. Upslope area is then calculated by proportioning flow between two downslope pixels according to how close this flow direction is to the direct angle to the downslope pixel. This procedure offers improvements over prior procedures that have restricted flow to eight possible directions (introducing grid bias) or proportioned flow according to slope (introducing unrealistic dispersion). The new procedure is more robust than prior procedures based on fitting local planes while retaining a simple grid based structure. Detailed algorithms are presented and results are demonstrated through test examples and application to digital elevation data sets. Introduction Flow direct...
Evaluation of Methods for Ridge and Valley Detection
 IEEE PAMI
, 1999
"... Abstract—Ridges and valleys are useful geometric features for image analysis. Different characterizations have been proposed to formalize the intuitive notion of ridge/valley. In this paper, we review their principal characterizations and propose a new one. Subsequently, we evaluate these characteri ..."
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Cited by 50 (3 self)
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Abstract—Ridges and valleys are useful geometric features for image analysis. Different characterizations have been proposed to formalize the intuitive notion of ridge/valley. In this paper, we review their principal characterizations and propose a new one. Subsequently, we evaluate these characterizations with respect to a list of desirable properties and their purpose in the context of representative image analysis tasks. Index Terms—Creases, separatrices, drainage patterns, comparative analysis. ————————— — F ——————————
Sciences Discussions
, 2007
"... Papers published in Hydrology and Earth System Sciences Discussions are under openaccess review for the journal Hydrology and Earth System Sciences Participatory scenario development for integrated assessment of nutrient flows in a Catalan river catchment ..."
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Cited by 34 (1 self)
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Papers published in Hydrology and Earth System Sciences Discussions are under openaccess review for the journal Hydrology and Earth System Sciences Participatory scenario development for integrated assessment of nutrient flows in a Catalan river catchment
On the effect of digital elevation model accuracy on hydrology and geomorphology
 Water Resources Research
, 1999
"... Abstract. This study compares published cartometric and photogrammetric digital elevation models (DEMs) of various grid spacings with a ground truth data set, obtained by ground survey, and studies the implications of these differences on key hydrologic statistics. Inferred catchment sizes and strea ..."
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Cited by 33 (0 self)
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Abstract. This study compares published cartometric and photogrammetric digital elevation models (DEMs) of various grid spacings with a ground truth data set, obtained by ground survey, and studies the implications of these differences on key hydrologic statistics. Inferred catchment sizes and stream networks from published DEMs were found to be significantly different than those from the ground truth in most instances. Furthermore, the width functions and cumulative area relationships determined from the published DEMs were found to fall consistently outside the 90 % confidence limits determined from the ground truth for more than 60 % of the relationship, suggesting that these hydrologic properties are poorly estimated from published DEMs. However, the slopearea relationships determined from published DEMs were found to be less sensitive to catchment shape, size, and stream network, with the relationship falling outside the 90 % confidence limits for less than 40 % of the relationship for all catchments identified from the published DEMs. A published relationship linking the horizontal resolution with the vertical accuracy of the DEM was tested, predicting a horizontal resolution of about 10 m for the published DEMs tested. 1.
I/OEfficient Algorithms for Problems on Gridbased Terrains (Extended Abstract)
 In Proc. Workshop on Algorithm Engineering and Experimentation
, 2000
"... Lars Arge Laura Toma Jeffrey Scott Vitter Center for Geometric Computing Department of Computer Science Duke University Durham, NC 277080129 Abstract The potential and use of Geographic Information Systems (GIS) is rapidly increasing due to the increasing availability of massive amoun ..."
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Cited by 30 (14 self)
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Lars Arge Laura Toma Jeffrey Scott Vitter Center for Geometric Computing Department of Computer Science Duke University Durham, NC 277080129 Abstract The potential and use of Geographic Information Systems (GIS) is rapidly increasing due to the increasing availability of massive amounts of geospatial data from projects like NASA's Mission to Planet Earth. However, the use of these massive datasets also exposes scalability problems with existing GIS algorithms. These scalability problems are mainly due to the fact that most GIS algorithms have been designed to minimize internal computation time, while I/O communication often is the bottleneck when processing massive amounts of data.
Drainage Queries in TINs: From local to global and back again
 In Proc. 7th Int. Symp. on Spatial Data Handling
, 1996
"... This paper considers the cost of preprocessing a digital terrain model (DTM) represented as a triangulated irregular network (TIN) so that drainage queriese.g., what is the watershed of a query point, or how much water passes through a point given that rain is falling at a known ratecan be ans ..."
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Cited by 29 (6 self)
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This paper considers the cost of preprocessing a digital terrain model (DTM) represented as a triangulated irregular network (TIN) so that drainage queriese.g., what is the watershed of a query point, or how much water passes through a point given that rain is falling at a known ratecan be answered by simply evaluating a summary function. Although the worstcase storage and preprocessing costs are high, the experimentallyobserved costs are reasonable. In order to compute a compact and consistent summary function, the drainage network needs a rigorous definition. This paper, therefore, also surveys some of the previous definitions, extends them, and establishes a number of properties of drainage networks with a focus on TINs. 1 Introduction Terrain drainage characteristics provide important information on water resources, possible flood areas, erosion and other natural processes. In natural resource management, for example, the basic management unit is the watershed, the area a...
Terrain Analysis Using Digital Elevation Models in Hydrology
, 2003
"... This paper describes methods that use digital elevation models (DEMs) in hydrology, implemented as an ArcGIS toolbar using Visual Basic and the ESRI object library. I describe generalized channel network delineation to objectively estimate drainage density and by using terrain curvature accommodate ..."
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Cited by 27 (1 self)
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This paper describes methods that use digital elevation models (DEMs) in hydrology, implemented as an ArcGIS toolbar using Visual Basic and the ESRI object library. I describe generalized channel network delineation to objectively estimate drainage density and by using terrain curvature accommodate spatially variable drainage density. The multiple flow direction field determined from a DEM also serves as a basis for routing overland and topographically driven subsurface flow useful in water quality, erosion and terrain stability modeling. New DEM derived quantities, such as downslope influence, upslope dependence, decayed accumulation, downslope accumulation and transport limited accumulation are illustrated.
2000: Multilocal creaseness based on the levelset extrinsic curvature. Computer Vision and Image Understanding 77(2
"... Creases are a type of ridge/valley structures of an image characterized by local conditions. As creases tend to be at the center of anisotropic greylevel shapes, creaseness can be considered a measure of medialness, and therefore as useful in many image analysis problems. Among the several possibil ..."
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Cited by 24 (8 self)
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Creases are a type of ridge/valley structures of an image characterized by local conditions. As creases tend to be at the center of anisotropic greylevel shapes, creaseness can be considered a measure of medialness, and therefore as useful in many image analysis problems. Among the several possibilities, a priori the creaseness based on the levelset extrinsic curvature (LSEC) is especially interesting due to its invariance properties. However, in practice, it produces a discontinuous response with a badly dynamic range. The same problems arise with other related creaseness measures proposed in the literature. In this paper, we argue that these problems are due to the very local definition of the LSEC. Therefore, rather than designing an ad hoc solution, we propose two new multilocal creaseness measures that we will show to be free of discontinuities and to have a meaningful dynamic range of response. Still, these measures are based on the LSEC idea, to preserve its invariance properties. We demonstrate the usefulness of the new creaseness measures in the context of two applications that we are currently developing in the field of 3D medical image analysis, the rigid registration of CT and MR head volumes and the orientation analysis of trabecular bone patterns. c ○ 2000 Academic Press Key Words: creases; curvature; divergence; structure tensor; trabecular bone; registration.
I/Oefficient batched unionfind and its applications to terrain analysis
 IN PROC. 22ND ANNUAL SYMPOSIUM ON COMPUTATIONAL GEOMETRY
, 2006
"... Despite extensive study over the last four decades and numerous applications, no I/Oefficient algorithm is known for the unionfind problem. In this paper we present an I/Oefficient algorithm for the batched (offline) version of the unionfind problem. Given any sequence of N union and find opera ..."
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Cited by 24 (9 self)
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Despite extensive study over the last four decades and numerous applications, no I/Oefficient algorithm is known for the unionfind problem. In this paper we present an I/Oefficient algorithm for the batched (offline) version of the unionfind problem. Given any sequence of N union and find operations, where each union operation joins two distinct sets, our algorithm uses O(SORT(N)) = O ( N B log M/B N I/Os, where M is the memory size and B is the disk block size. This bound is asymptotically optimal in the worst case. If there are union operations that join a set with itself, our algorithm uses O(SORT(N) + MST(N)) I/Os, where MST(N) is the number of I/Os needed to compute the minimum spanning tree of a graph with N edges. We also describe a simple and practical O(SORT(N) log ( N M))I/O algorithm for this problem, which we have implemented. We are interested in the unionfind problem because of its applications in terrain analysis. A terrain can be abstracted as a height function defined over R2, and many problems that deal with such functions require a unionfind data structure. With the emergence of modern mapping technologies, huge amount of elevation data is being generated that is too large to fit in memory, thus I/Oefficient algorithms are needed to process this data efficiently. In this paper, we study two terrainanalysis problems that benefit from a unionfind data structure: (i) computing topological persistence and (ii) constructing the contour tree. We give the first O(SORT(N))I/O algorithms for these two problems, assuming that the input terrain is represented as a triangular mesh with N vertices. Finally, we report some preliminary experimental results, showing that our algorithms give orderofmagnitude improvement over previous methods on large data sets that do not fit in memory.