山顶点提取方法决定着山体部位划分结果的正确性和微地形自动分类效率.以高程和等高线为参考提取山顶点的方法存在伪山顶点剔除不完全和局部山顶点丢失的问题,依据山顶点邻域坡向呈均匀分布规律,提出了基于坡向分布特征的山顶点提取方法,构建了以山顶点为中心的邻域坡向顺时针逐渐递增模型,并以山脊线拟合和深度优先搜索(depth first search,DFS)算法的递推思想,剔除提取结果中的伪山顶点.顾及实体数字高程模型(digital elevation model,DEM)地形破碎对提取方法的影响,采用了模拟DEM和实体DEM分别进行实验和分析.实验结果表明,坡向分布特征法避免了传统基于封闭等高线提取山顶点时主观选取阈值的不确定性;模拟DEM因其连续、光滑,山顶点提取准确率可达到100％,而实体DEM沿用模拟DEM机制,因其地形破碎导致的不可适性,通过调整坡向分布约束条件可予以改善,实验提取准确率平均可达到96.1％.
Mountain Peak Extraction of Grid DEM Based on Aspect Distribution Feature
Objects:Mountain peak extraction technology determines the accuracy of the hill position classi-fication and the efficiency of automatic classification of micro-landform.Because of the limitations of eleva-tion and contour lines,such as loss of local mountain peaks and incomplete removal of false mountain peaks,other landform factors could be used to express the distribution feature around the mountain peaks.Methods:Based on the uniform distribution feature of the aspect around the mountain peaks,this paper pro-poses an efficient mountain peak extraction model,in which the aspect is centered on the mountain peak and gradually increases clockwise.Moreover,according to the ridge line fitting method and the recursive thought of depth first search algorithm,the false mountain peaks in the extraction results are removed,while the real mountain peaks are retained.Considering the negative influences of the terrain fragmentation of the entity digital elevation model(DEM),this paper experiments and analyzes with simulated DEM and entity DEM respectively.Results:The results show that the method overcomes the uncertainty of subjec-tive threshold based on closed contour lines.The mountain peak extraction accuracy of simulated DEM can achieve 100％due to its continuity and smoothness.Considering the terrain fragmentation of entity DEM will make it ill-posed,we improve it by adjusting the aspect distribution constraint condition and obtain av-erage extraction accuracy of 96.1％.Conclusions:An efficient mountain peak extraction model is proposed based on the digital terrain analysis technology and the uniform distribution feature of the aspect around the mountain peaks,and the topographic feature points are extracted from the perspective of terrain geometry.Compared with the traditional mountain peak extraction methods,the proposed method is relatively accu-rate and simple,and can effectively reduce the false mountain.
digital terrain analysisgrid DEMaspectmountain peakdistribution feature
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