54,799 research outputs found

    Seafloor characterization using airborne hyperspectral co-registration procedures independent from attitude and positioning sensors

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    The advance of remote-sensing technology and data-storage capabilities has progressed in the last decade to commercial multi-sensor data collection. There is a constant need to characterize, quantify and monitor the coastal areas for habitat research and coastal management. In this paper, we present work on seafloor characterization that uses hyperspectral imagery (HSI). The HSI data allows the operator to extend seafloor characterization from multibeam backscatter towards land and thus creates a seamless ocean-to-land characterization of the littoral zone

    A Preliminary Assessment of Tidal Flooding along the New Hampshire Coast: Past, Present and Future

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    This report presents the results of a preliminary study that examines several critical coastal issues for New Hampshire including sea level fluctuations (past, present and future), shoreline migrations, and tidal flooding. Included are: 1) an analysis of sea level changes over the Holocene and resulting shoreline migrations, 2) an assessment of low-lying areas with elevations below selected tidal flooding datums in coastal areas, and 3) an assessment of increases in low-lying areas that are potentially at risk to tidal flooding over the next century due to sea level rise

    Comparison of free high resolution digital elevation data sets (ASTER GDEM2, SRTM v2.1/v4.1) and validation against accurate heights from the Australian National Gravity Database

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    Today, several global digital elevation models (DEMs) are freely available on the web. This study compares and evaluates the latest release of the Advanced Spaceborne Thermal Emission Reflectometer DEM (ASTER GDEM2) and two DEMs based on the Shuttle Radar Topography Mission (SRTM) as released by the United States Geological Survey (SRTM3 USGS version 2.1) and by the Consortium for Spatial Information (SRTM CGIAR-CSI version 4.1) over the Australian continent. The comparison generally shows a very good agreement between both SRTM DEMs; however, data voids contained in the USGS model over steep topographic relief are filled in the CGIAR-CSI model. ASTER GDEM2 has a northeast- to southwest-aligned striping error at the 10 m level and shows an average height bias of –5 m relative to SRTM models. The root-mean square (RMS) height error obtained from the differences between ASTER GDEM2 and SRTM over Australia is found to be around 9.5 m. An external validation of the models with over 228 000 accurate station heights from the Australian National Gravity Database allows estimating each models’ elevation accuracies over Australia: ASTER GDEM2 ~ 8.5 m, SRTM3 USGS ~ 6 m, SRTM CGIAR-CSI ~ 4.5 m (RMS). In addition, the dependence of the DEM accuracy on terrain type and land cover is analysed. Applying a cross-correlation image co-registration technique to 529 1 × 1 degree tiles and 138 2 × 2 degree tiles reveals a mean relative shift of ASTER GDEM2 compared with SRTM of –0.007 and –0.042 arc-seconds in north–south and –0.100 and –0.136 arc-seconds in east–west direction over Australia, respectively

    Web-Based Roadway Geometry Design Software for Transportation Education

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    Traditionally, students use pencil and ruler to lay out lines and curves over contour maps for roadway geometry design. Numerous calculations of stopping sight distance, minimum turning radius, and curve alignments are required during the roadway design process in order to ensure safety, to minimize economic and environmental impacts, as well as to reduce construction costs. Iterative computations during the design process are usually performed manually by the students in order to meet any given design criteria and environmental constraints. The traditional design process of roadway geometry design is often cumbersome and time consuming. It limits students from taking a broader perspective on the overall roadway design process. An Internet-based roadway design tool (ROAD: Roadway Online Application for Design) was developed to enhance the learning experience for transportation engineering students. This tool allows students to efficiently design and to easily modify the roadway design with given economic and environmental parameters. A 3D roadway geometry model can be generated by the software at final design to allow students immerse themselves in the driver’s seat and drive through the designed roadway at maximum design speed. This roadway geometry design tool was deployed and tested in a civil engineering undergraduate class in spring 2006 at University of Minnesota, Department of Civil Engineering. Feedback was collected from instructors and students that will lead to additional enhancements of the roadway design software.

    Applied surveying education : documenting cultural heritage in 3D in the city of Ghent (Belgium) using laser scanning and photo modelling

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    For several years the city of Ghent (Belgium) and the Ghent University, Department of Geography have been working together to document and measure important cultural heritage sites in 3D. The partnership enables master students in Geomatics and Surveying at the Ghent University to take part in a project driven measuring campaign. During the project, students use and compare several 3D data acquisition methods. This allows the students to implement their theoretical knowledge in the field. The used methods are analysed and critically compared by the students. Through this hands-on-training, students are encouraged to think “outside the box”. When problems occur, they are stimulated to think how these problems could have happened and most importantly how they can solve them. The documentation of these historic monuments in Ghent will be used during future renovation works and archaeological research. This paper will discuss the measurements in the Ghent City Museum (Stadsmuseum or STAM). The following methods are applied during the extensive field work: engineering surveying using total station and GNSS, photo modelling and laser scanning. The deliverables are created in a CAD or GIS environment. After successful completion of the course, students have gained a significant expertise concerning the processing of topographic data, 3D point clouds and imagery in an integrated way. This knowledge can be used after their studies to assess which equipment is most suitable for any given survey project. The final products of the photo modelling and the laser scanning process is a 3D model. Furthermore, digital elevation models and orthorectified images of the historic monument can be created. The orthorectified images are visualised and processed into high resolution orthophoto plans, in a CAD or GIS environment

    Geographically Referenced Data for Social Science

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    An estimated 80% of all information has a spatial reference. Information about households as well as environmental data can be linked to precise locations in the real world. This offers benefits for combining different datasets via the spatial location and, furthermore, spatial indicators such as distance and accessibility can be included in analyses and models. HSpatial patterns of real-world social phenomena can be identified and described and possible interrelationships between datasets can be studied. Michael F. GOODCHILD, a Professor of Geography at the University of California, Santa Barbara and principal investigator at the Center for Spatially Integrated Social Science (CSISS), summarizes the growing significance of space, spatiality, location, and place in social science research as follows: "(...) for many social scientists, location is just another attribute in a table and not a very important one at that. After all, the processes that lead to social deprivation, crime, or family dysfunction are more or less the same everywhere, and, in the minds of social scientists, many other variables, such as education, unemployment, or age, are far more interesting as explanatory factors of social phenomena than geographic location. Geographers have been almost alone among social scientists in their concern for space; to economists, sociologists, political scientists, demographers, and anthropologists, space has been a minor issue and one that these disciplines have often been happy to leave to geographers. But that situation is changing, and many social scientists have begun to talk about a "spatial turn," a new interest in location, and a new "spatial social science" that crosses the traditional boundaries between disciplines. Interest is rising in GIS (Geographic Information Systems) and in what GIS makes possible: mapping, spatial analysis, and spatial modelling. At the same time, new tools are becoming available that give GIS users access to some of the big ideas of social science."
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