224 research outputs found

    Lidar In Coastal Storm Surge Modeling: Modeling Linear Raised Features

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    A method for extracting linear raised features from laser scanned altimetry (LiDAR) datasets is presented. The objective is to automate the method so that elements in a coastal storm surge simulation finite element mesh might have their edges aligned along vertical terrain features. Terrain features of interest are those that are high and long enough to form a hydrodynamic impediment while being narrow enough that the features might be straddled and not modeled if element edges are not purposely aligned. These features are commonly raised roadbeds but may occur due to other manmade alterations to the terrain or natural terrain. The implementation uses the TauDEM watershed delineation software included in the MapWindow open source Geographic Information System to initially extract watershed boundaries. The watershed boundaries are then examined computationally to determine which sections warrant inclusion in the storm surge mesh. Introductory work towards applying image analysis techniques as an alternate means of vertical feature extraction is presented as well. Vertical feature lines extracted from a LiDAR dataset for Manatee County, Florida are included in a limited storm surge finite element mesh for the county and Tampa Bay. Storm surge simulations using the ADCIRC-2DDI model with two meshes, one which includes linear raised features as element edges and one which does not, verify the usefulness of the method

    Analysis and exploitation of landforms for improved optimisation of camera based wildfire detection systems

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    Tower-mounted camera-based wildfire detection systems provide an effective means of early forest fire detection. Historically, tower sites have been identified by foresters and locals with intimate knowledge of the terrain and without the aid of computational optimisation tools. When moving into vast new territories and without the aid of local knowledge, this process becomes cumbersome and daunting. In such instances, the optimisation of final site layouts may be streamlined if a suitable strategy is employed to limit the candidate sites to landforms which offer superior system visibility. A framework for the exploitation of landforms for these purposes is proposed. The landform classifications at 165 existing tower sites from wildfire detection systems in South Africa, Canada and the USA are analysed using the geomorphon technique, and it is noted that towers are located at or near certain landform types

    Tracking Dynamic Features in Image Sequences.

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    This dissertation deals with detecting and tracking dynamic features in image sequences using digital image analysis algorithms. The tracking problem is complicated in oceanographic images due to the dynamic nature of the features. Specifically, the features of interest move, change size and shape. In the first part of the dissertation, the design and development of a new segmentation algorithm, Histogram-based Morphological Edge Detector (HMED), is presented. Mathematical morphology has been used in the past to develop efficient and robust edge detectors. But these morphological edge detectors do not extract weak gradient edge pixels, and they introduce spurious edge pixels. The primary reason for this is due to the fact that the morphological operations are defined in the domain of a pixel\u27s neighborhood. HMED defines new operations, namely H-dilation and H-erosion, which are defined in the domain of the histogram of the pixel\u27s neighborhood. The motivation for incorporating the histogram into the dilation and erosion is primarily due to the rich information content in the histogram compared to the one available in the pixel\u27s neighborhood. As a result, HMED extracts weak gradient pixels while suppressing the spurious edge pixels. An extensive comparison of all morphological edge detectors in the context of oceanographic digital images is also presented. In the second part of the dissertation, a new augmented region and edge segmentation technique for the interpretation of oceanographic features present in the AVHRR image is presented. The augmented technique uses a topography-based method that extracts topolographical labels such as concave, convex and flat pixels from the image. In this technique, first a bicubic polynomial is fitted to a pixel and its neighborhood, and topolographical label is assigned based on the first and second directional derivatives of the polynomial surface. Second, these labeled pixels are grouped and assembled into edges and regions. The augmented technique blends the edge and region information on a proximity based criterion to detect the features. A number of experimental results are also provided to show the significant improvement in tracking the features using the augmented technique over other previously designed techniques

    Digital Elevation Models in Geomorphology

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    This chapter presents place of geomorphometry in contemporary geomorphology. The focus is on discussing digital elevation models (DEMs) that are the primary data source for the analysis. One has described the genesis and definition, main types, data sources and available free global DEMs. Then we focus on landform parameters, starting with primary morphometric parameters, then morphometric indices and at last examples of morphometric tools available in geographic information system (GIS) packages. The last section briefly discusses the landform classification systems which have arisen in recent years

    Investigation of natural environment by space means. Geobotany, Geomorphology, soil sciences, agricultural lands, landscape study

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    Reports given by Soviet specialists at a meeting of Socialist countries on remote sensing of the earth using aerospace methods are presented

    The High Resolution Imaging Science Experiment (HiRISE) during MRO’s Primary Science Phase (PSP)

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    Cornell University remote sensing program

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    The major activities of the program staff from December 1, 1973 to May 31, 1974 are reported and include: (1) communication and instruction; (2) data and facilities; (3) research completed; (4) research in progress; (5) selected correspondence; (6) grant sponsored travel; and (7) seminars and newsletters. Detailed information and maps are given for the following selected projects: (1) ERTS mapping of waterways in the Tug Hill region of New York State; (2) photo-archeological investigation of Great Gully, New York; and (3) evaluation of selected highway impacts using aerial photography

    Analyses of Potential Ravine and Bluff Stabilization Sites within the Blue Earth and Le Sueur River Basins

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    The United States Environmental Protection Agency (USEPA) has listed much of the Upper Mississippi River (UMR) basin as impaired waters due to excessive turbidity, sedimentation, and nutrient loading. Of particular importance are the associated environmental problems (e.g. eutrophication, habitat and wetland loss, loss of biodiversity, and changes in water quality) that have developed within Lake Pepin, a popular recreational riverine lake of the UMR. Three major drainages contribute to these issues and empty in to the UMR near Lake Pepin - the Minnesota River Basin (MRB), St. Croix River, and UMR. The MRB makes up approximately one-third of the drainage area above Lake Pepin, but has been found to contribute approximately 85-90% of all sediment entering the lake – both in the past and present. A major tributary system of the MRB, the Blue Earth River Basin (BERB) and its subbasins, contribute as much as half of the sediment exiting the Minnesota River, despite accounting for only one-fifth of the MRB drainage area. The tremendous sediment yields from this basin are a result of both post-glacial landscape evolution and contemporary land-use practices. Recent radioisotopic fingerprinting of these sediments has helped narrow the focus of mitigations strategies as they indicate that the majority of the sediment originates from near-channel sources in the MRB, specifically ravines and bluffs. Significantly, it was also found that the rate of sedimentation has increased ten-fold over the past 150 years. Thus, mitigations strategies to curtail the sediment yields arriving downstream should focus on the near-channel sources of the BERB and its subbasins. Unfortunately, the resolution of radioisotopic methods is inadequate in locating of specific near-channel sources on which to implement mitigation strategies. Therefore, a crucial first step of an effective mitigation strategy to reduce erosion is to develop a methodology that aids in identifying the precise geographic position of ravines and bluffs with high erosion potential. This study uses Geographic Information Systems (GIS) to compile county Light Detection and Ranging (LiDar) and elevation, watershed and stream network, county infrastructure (private and public buildings and roads), county and watershed soil, county and watershed land use data in the BERB and its subbasins, to attempt to locate precise locations of ravines and bluffs with high erosion potential. Using two LiDar data sets taken in 2005 and 2012, and incorporating net sediment loss, slope grade, soil material, soil texture, connectivity to river, distance to river, surrounding adjacent land use, proximity and threat to roads, proximity and threat to public and private buildings, accessibility from roads, visibility from stream, and visibility from roads; 14 ravines and 10 bluffs were identified in the BERB, and 18 ravines and 29 bluffs were identified in the BERB, the Le Sueur River Basin (LSRB). These ravine and bluff sites exhibited an abundant amount of erosion between 2005 and 2012. As a baseline study, a comprehensive review of hydrologic and sediment transport models and stabilization techniques were completed to provide natural resource managers tools to stabilize and effectively manage these erosive sites. Preliminarily, this thesis study provides an effective protocol for identifying potential mitigation/stabilization sites that are not readily accessible with conventional surveying equipment. The models and stabilization techniques reviewed are effective strategies for watershed management in highly geomorphically active regions. Moving forward, a future LiDar dataset is recommended for further temporal and spatial analysis of the identified sites. Moreover, long-term monitoring of selected sites are recommended in order to isolate parameters to model erosion events, determine rates of change, and further understand the evolution of the landscape for effective watershed management

    Towards extracting artistic sketches and maps from digital elevation models

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    The main trend of computer graphics is the creation of photorealistic images however, there is increasing interest in the simulation of artistic and illustrative techniques. This thesis investigates a profile based technique for automatically 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 most important points on the terrain surface to be identified, these form the basis for sketching.This thesis also contains a wide ranging review of terrain representation techniques and suggests a new taxonomy

    Field reconnaissance geologic mapping of the Columbia Hills, Mars, based on Mars Exploration Rover Spirit and MRO HiRISE observations

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    Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geologic history is well exposed, stratigraphic units may be identified and correlated across significant areas on the ground, and outcrops and geologic relationships between materials may be analyzed with techniques commonly employed in terrestrial field geology. Despite their burial during the course of Martian geologic time by widespread epiclastic materials, mobile fines, and fall deposits, the selective exhumation of deep and well-preserved geologic units has exposed undisturbed outcrops, stratigraphic sections, and structural information much as they are preserved and exposed on Earth. A rich geologic record awaits skilled future field investigators on Mars. The correlation of ground observations and orbital images enables construction of a corresponding geologic reconnaissance map. Most of the outcrops visited are interpreted to be pyroclastic, impactite, and epiclastic deposits overlying an unexposed substrate, probably related to a modified Gusev crater central peak. Fluids have altered chemistry and mineralogy of these protoliths in degrees that vary substantially within the same map unit. Examination of the rocks exposed above and below the major unconformity between the plains lavas and the Columbia Hills directly confirms the general conclusion from remote sensing in previous studies over past years that the early history of Mars was a time of more intense deposition and modification of the surface. Although the availability of fluids and the chemical and mineral activity declined from this early period, significant later volcanism and fluid convection enabled additional, if localized, chemical activity
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