Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 97 for “"digital elevation models"”.
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The Robust Compression of Digital Elevation Models
The representation of terrain by a regular grid Digital Elevation Model (DEM) requires a large amount of data which increases with the resolution. The nature of the typical applications of terrain data, for example, aeronautical navigation, dictates that the reliability of the data is of prime …
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Towards extracting artistic sketches and maps from digital elevation models
… extracting artistic sketches from regular grid digital elevation models. The results resemble those drawn by skilled cartographers and artists.The use of cartographic line simplification algorithms, which are usually applied to complex two-dimensional lines such as coastlines, allow a set of …
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Enhancement of digital elevation models using tree-based ensemble machine learning algorithms
… and topographic map revision. Thus, global digital elevation models (DEMs) have gained worldwide prominence due to their free availability; a prime advantage when compared to prohibitively expensive airborne topographic surveys. However, the accuracies of global DEMs are affected by several …
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An automated method for locating sinkholes in Montgomery County, Virginia, using digital elevation models
The prospect of using U.S.G.S. Digital Elevation Models (DEM's) to locate sinkholes has been investigated. Three quadrangle maps, those of Blacksburg, Ironto and Newport, were selected as these areas are dotted with sinkholes. An algorithm was developed to extract sinkholes from DEM's. Sinkholes …
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Comparison of Two Algorithms for Removing Depressions and Delineating Flow Networks From Grid Digital Elevation Models
Digital elevation models (DEMs) and their derivatives such as slope, flow direction and flow accumulation maps, are used frequently as inputs to hydrologic and nonpoint source modeling. The depressions which are frequently present in DEMs may represent the actual topography, but are often the …
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Analysis of Viewshed Accuracy with Variable Resolution LIDAR Digital Surface Models and Photogrammetrically-Derived Digital Elevation Models
… Viewsheds are often generated using "bare-earth" Digital Elevation Models (DEMs) derived from the process of photogrammetry. More detailed models, known as Digital Surface Models (DSMs), are often generated using Light Detection and Ranging (LIDAR) which uses an airborne laser to scan the terrain. …
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An investigation into the design of a satellite based stereo imaging sensor and the use of automatic image matching in the production of digital elevation models
… imaging sensor and the automatic matching of digital stereo images for automatic cartography applications. The two problems are related; they are both components of a stereo vision system. The research was initially motivated by the decision of the Department of Electrical and Electronic …
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Use of the fractal dimension in characterization of terrestrial surfaces
… the resolved surface area and volume of digital elevation models were utilized in evaluating the fractal dimension. Three digital elevation models (DEM) were examined with respect to area and volume. Changes in scale and grid data resolution were simulated by decreasing the grid sampling …
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Análisis de Modelos Digitales de Elevaciones (MDE) generados con imágenes SPOT-HRV y TERRA-ASTER
… space-SPOT HRV and Terra-ASTER, for generating digital elevation models, MDE, using techniques automatic correspondence. To that end, we analyze the variables that influenced in the generation the MDE as: number and distribution of control points, data structure, size of grid, algorithm of …
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LiDAR-Based Analysis of Antebellum-Era Sugar Mill Remains in Brazoria County, Texas: Investigations from Above and Below
… aims to assess the efficacy of LiDAR-derived digital elevation models in identifying historical surficial features, effectively complementing the conventional excavation and geophysical surveying methods employed thus far. The study involves the acquisition and processing of LiDAR data to …
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An Analysis and Critique of DEM Creaion and 3-D Modeling Using Airborne LIDAR and Photogrammetric Techniques
… tool for many engineering projects. Accurate digital representations of terrain and ground features are extremely useful for efficient design, communication and data representation in projects involving land development, transportation planning, hydrologic analysis, environmental impact …
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The Effect of Digital Elevation Model Resolution on Wave Propagation Predictions at 24Ghz
Digital Elevation Models (DEMs) are computer-generated representations of the earth's surface. These surfaces can be used to predicted Line-of-Sight (LOS) radio propagation. DEM resolution can affect the results of this prediction. This study examines the effect of DEM resolution on accuracy by …
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Prediction of stream channel location from drainage basin boundaries
… representations of drainage networks from raster digital elevation models for hydrological and geomorphological applications are similar to a class of image processing methods known as grayscale watershed algorithms. These algorithms partition a field of scalar values into connected regions based …
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Multispectral Remote Sensing of the Earth and Environment Using KHawk Unmanned Aircraft Systems
… generated aerial maps and their corresponding Digital Elevation Models (DEMs) are used for typical application scenarios including prescribed fire monitoring, initial fire line estimation, and tree health monitoring.
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An inventory and mapping of cliffs within the South Cumberland Plateau region of Tennessee
… This study examined the use of LiDAR-derived digital elevation models (DEMs) to (1) create an exhaustive dataset of cliffs throughout a two-county study area within the SCP region and (2) better understand the implications of this quantification on conservation and rock climbing within the …
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