Wavelet transform is an important pretreatment tool to extract texture information, which can decompose
image as different level and provide rich detail information. But the tool is fit to any size spatial resolution image? The
paper gives several tests and extracts texture information from high and medium spatial resolution images, compares the
texture information; what's more, image classification is tested too. The result shows that wavelet transform cannot provide effective texture information for medium spatial resolution image.
Viewshed analysis is a method and technology, which manages geometry principles and computer graphic technology to
resolve the problem of geographic aggregation of monitoring points. This paper analyses the forest resources and its main
fire prevention factors, such as forest types, forest ages and forest shade density etc., within the scope of the visible
monitoring points, and discusses how to maximize the area under forest fire monitoring without increasing the number of
monitoring points and changing equipments performance. With the target of maximuming monitoring area, the paper
studies on the best monitoring position within certain area, and to convert it into how to optimize the visible area so as to
make locating monitoring points much more scientific, reasonable and efficient.
Contour line is a closed curve that joined by points of the same elevation. This paper puts forward a new algorithm of creating contour line based on DEM, which uses the method of tracking the same elevation point to study the algorithm based on regular grid. This paper will be divided the algorithm of creating contour line into four sub-algorithms, namely: the algorithm of elevation comparison; the algorithm of calculating the same elevation point coordinates; the algorithm of tracking next point of the same elevation, the algorithm of tracking contour line. The algorithm of elevation
comparison is mainly used in judging whether a contour line with appointed elevation passes through a side of the grid; the algorithm of calculating the same elevation point coordinates is used to calculate coordinates of contour lines across the grid's side; function of the algorithm of tracking next point of the same elevation is to track next point of the same elevation by following the trend of contour lines; the algorithm of tracking contour line aims in tracking coordinates of the point which has the equal value of elevation with the point in row x and column y.
Based on GIS technology, this paper mainly focuses on the application of disaster assessment algorithm after forest fire and studies on the design and realization of disaster assessment based on GIS. After forest fire through the analysis and processing of multi-sources and heterogeneous data, this paper integrates the foundation that the domestic and foreign scholars laid of the research on assessment for forest fire loss with the related knowledge of assessment, accounting and forest resources appraisal so as to study and approach the theory framework and assessment index of the research on assessment for forest fire loss. The technologies of extracting boundary, overlay analysis, and division processing of multi-sources spatial data are available to realize the application of the investigation method of the burnt forest area and the computation of the fire area. The assessment provides evidence for fire cleaning in burnt areas and new policy making on restoration in terms of the direct and the indirect economic loss and ecological and environmental damage caused by forest fire under the condition of different fire danger classes and different amounts of forest accumulation, thus makes forest resources protection operated in a faster, more efficient and more economical way. Finally, this paper takes Lin'an city of Zhejiang province as a test area to confirm the method mentioned in the paper in terms of key technologies.
Contour line is a closed curve that joined by points of the same elevation. This paper puts forward a new algorithm of
creating contour line based on DEM, which uses the method of tracking the same elevation point to study the algorithm
based on regular grid. This paper will be divided the algorithm of creating contour line into four sub-algorithms, namely:
the algorithm of elevation comparison, the algorithm of calculating the same elevation point coordinates, the algorithm
of tracking next point of the same elevation, the algorithm of tracking contour line. The algorithm of elevation
comparison is mainly used in judging whether a contour line with appointed elevation passes through a side of the grid;
the algorithm of calculating the same elevation point coordinates is used to calculate coordinates of contour lines across
the grid's side; function of the algorithm of tracking next point of the same elevation is to track next point of the same
elevation by following the trend of contour lines; the algorithm of tracking contour line aims in tracking coordinates of
the point which has the equal value of elevation with the point in row x and column y.
KEYWORDS: Particles, Computer simulations, Data modeling, Visual process modeling, Visualization, Associative arrays, 3D modeling, OpenGL, Atmospheric modeling, C++
This paper uses the McArthur forest fire spread model, takes Visual C++ and OpenGL(Open Graphics Library) development kit, and experiments on the region of the Zhejiang Province Linan by using this city 1: 50000 DEM(Digital Elevation Model) data, investigations data of forest resources, unifies the real-time meteorological data, and researches the method of forest-fire spread simulation based on the 3D(three-dimension), which studies Forest fire production and the spread simulator method with its related algorithm in emphasis. The paper takes the forest fire production and spread method as the foundation to propose and design six algorithms to successively simulate the forest fire spread. Respectively: The fire that spreads in different directions algorithm, distributed fire points algorithm, scene of a fire region computation algorithm, mapping fire particle algorithm, flame production algorithm, and billboard technology application algorithm.
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