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721.
Comparison of requirements for modeling snowdrift in the case of outdoor and wind tunnel experiments 总被引:1,自引:0,他引:1
Florence Naaim-Bouvet 《Surveys in Geophysics》1995,16(5-6):711-727
This paper reports on modeling of drifting snow phenomena. It comprises a review of the conditions for a correct simulation of snowdrifting in wind-tunnel or outdoor comparing requirements proposed by four scientists (Kind, 1975, 1985; Iversen, 1979, 1980, 1981, 1982, 1984; Anno, 1984, Tabler, 1980). Comparisons of these requirements were based on full-scale measurements, wind tunnel simulation, outdoor modeling with snow or sand. 相似文献
722.
723.
Pattern based map comparisons 总被引:5,自引:0,他引:5
Roger White 《Journal of Geographical Systems》2006,8(2):145-164
Map comparison techniques based on a pixel-by-pixel comparison are useful for many purposes, but fail to reveal important aspects of map similarities and differences. In contrast, pattern based map comparison techniques address the question of structural similarity, although with these approaches the comparison problem becomes open ended, since there is an unlimited number of ways to characterise a pattern. Two types of pattern based technique are used here to analyse the test sets of maps. The first, a fuzzy polygon based matching technique, focuses on the meso-scale aspects of pattern. It is based on the areal intersection of land use polygons on the two maps being compared. The areal intersection, areal complement, and polygon size values are fuzzified into an appropriate set of categories, a set of fuzzy inference rules is applied to derive memberships in local matching categories, and finally the local matching category memberships are defuzzified to yield local matching values for each land use polygon on the reference map. The second approach, fractal analysis, captures macro-scale or global qualities of the maps. Two measures are calculated here: the radial dimension and the cluster size—frequency dimension. The polygon matching approach provides only limited insight when applied to the case of the map set representing differences in classification. It proves much more effective when applied to the problem of change detection, revealing areas where the pattern has changed and giving local measures of the degree of change. The approach is particularly useful in the case where there is a considerable degree of random change at the pixel level, as changes in the underlying pattern are extracted from the noise, while pixel based approaches largely detect the noise. 相似文献
724.
应用于面状地理实体聚类分析的线段链形状相似性准则 总被引:1,自引:0,他引:1
提出了一种满足旋转与平移不变性的线段链形状相似性评价方法。该方法计算简便,适用于面状地理实体聚类分析,并给出了该评价方法的实现算法,分析了参数对评价方法可能产生的影响及影响程度。 相似文献
725.
基于等高线特性的三维表面重建方法的研究 总被引:5,自引:0,他引:5
黄培之 《武汉大学学报(信息科学版)》2005,30(8):668-672
研究了相邻等高线形状的变化规律,得出相邻等高线形状变化具有相似性的结论,而决定这种相似性的根本因素是相邻等高线之间的三维地形高程起伏变化的自然情况。以该规律为理论依据,研究出了一种基于等高线相似性变化特性的三维表面重建方法。实验结果表明,该方法能够充分利用等高线所含有的地形高程信息,较好地实现三维表面重建。 相似文献
726.
针对地图目标中许多线状要素具有典型统计分形特征的性质,探讨了在理想分形规则基础上通过增加随机因子,从而根据分维数反过来模拟构建地图曲线的方法. 相似文献
727.
在三维激光扫描仪使用过程中,为了减小点云拼接时的误差问题,本文利用同方差多元变量的EIV(Errors In Variables)模型及总体最小二乘的方法解决三维空间点的相似变换,较传统的迭代算法计算空间坐标转换的方法,具有非迭代性、可靠性和计算过程中的简便性。最后,利用实际工程案例对非迭代算法的有效性进行了验证。 相似文献
728.
从灾后机载激光点云自动检测损毁房屋的等高线簇分析方法 总被引:1,自引:0,他引:1
利用灾后机载激光扫描点云的地震损毁房屋检测方法主要针对平面屋顶房屋,从局部分析屋顶的平面特征,导致只能有效检测屋顶严重破碎的损毁房屋。为此本文提出了一种等高线簇相似分析的地震损毁房屋检测方法,充分挖掘房屋等高线簇蕴含的房屋表面形状丰富的二维和三维信息,利用等高线簇形状相似度的归一化信息熵从整体上综合描述损毁房屋的损毁特征,并利用最大熵模型自动检测损毁房屋。采用2010年4月El Mayor-Cucapah地震断裂带激光点云数据进行了试验,证明本文提出的方法能快速、准确、可靠地检测损毁房屋。 相似文献
729.
730.
Mohammad Sharif 《地理信息系统科学与遥感》2017,54(3):426-452
Analyzing the spatial behaviors of moving-point objects (MPOs) and discovering their movement patterns have been of great interest to the geographic information science community recently. These interests can be explored through analyzing similarities in the MPO trajectories. Because movements of objects take place in various contexts, their trajectories are also highly influenced by such contexts. Therefore, it is essential to fully understand the contexts and to realize how they can be incorporated into movement analysis. This article first proposes a taxonomy for contexts. Then, a modified version of dynamic time warping called context-based dynamic time warping (CDTW) is introduced, to contextually assess the multidimensional weighted similarities of trajectories. Ultimately, the results of similarity searches are utilized in discovering the relative movement patterns of the MPOs. To evaluate the performance and effectiveness of our proposed CDTW method, we run several experiments on real datasets that were obtained from commercial airplanes in a constrained Euclidean space, taking into account contextual information. Specifically, these experiments were conducted to explore the role of contexts and their interactions in similarity measures of trajectories. The results yielded the robustness of CDTW method in quantifying the commonalities of trajectories and discovering movement patterns with 80% accuracy. Moreover, the results revealed the importance of exploiting contextual information because it can enhance and restrict movements. 相似文献