Research And Application For Algorithm For Buffer Creation In Spatial Analysis

Space Analysis is the core and one of the key functions of Spatial Information System, also an important indicator to evaluate its function performance. Buffer analysis is the basis upon which many spatial analysis methods are built; as a basic spatial analysis function, buffer analysis serves to create a width of zone surrounding some geographic entity or spatial entity so as to identify the entity's proximity or influence over its boundary. Based on the current research in Buffer Analysis, and backed by theoretical and technological advance in computer graphics, computational geometry and spatial information systems, this thesis conducts a tentative research and analysis of buffer boundary creation algorithm; aided by Angular Bisector Algorithm and Salient Arc Algorithm, the paper presents an segmental buffer generation algorithm featuring planar scanning and applies the algorithm to the project "Dongguan Three-prevention Decision-making Support Systems".The segmental buffer generation algorithm featuring planar scanning is illustrated with the example of line object. To analyze and realize this algorithm, the thesis mainly covers:First, analyze traditional buffer generation algorithms and some recent algorithms, and review the problems when implementing those algorithms.Second, present the segmental buffer generation algorithm featuring planar scanning which is dealt with in following aspects: dispersing a continuous entity boundary line curve to line segments sets; representing the buffer boundary with the arc and the line segments in the process, at turning point , a direct use of arc rather than folding simulation arc segment significantly reduces the number of boundary line, thus speeding up intersection calculation process among buffer lines; applying the symmetric, dissymmetrical and half buffer processing of buffer radius, and flat head and round head processing at starting point and end-point; introducing planar scanning into plane curve intersection; improving the procedures in the removal of redundant points; and verifying the algorithm through emulated experiment.Third, apply the segmental buffer generation algorithm featuring planar scanning to the project "Dongguan Three-prevention Decision-making Support Systems", provide a reliable basis for other analysis and enhance the system's spatial analysis functions.