It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spati...It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spatial structure unit was generated based on the Delaunay triangulation model(DTM),and the weights were generated using the comprehensive values of the tree diameter at breast height,total height and crown width.The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates.Then,a weighted spatial pattern(WSP)was developed.After weighting,the neighboring trees were replaced,the replacement ratio was 38.3%,and there was 57.4%of the central tree.Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity(r=0.932)and randomness(r=0.711).The DTM method not only considers the spatial distance between trees,but also considers the non-spatial attributes of trees.By changing the spatial topological relation between trees,this method further improves the spatial structure measurement of forest.展开更多
Digital Elevation Models(DEMs)play a crucial role in civil and environmental applications,such as hydrologic and geologic analyses,hazard monitoring,natural resources exploration,etc.Generally,DEMs can be generated fr...Digital Elevation Models(DEMs)play a crucial role in civil and environmental applications,such as hydrologic and geologic analyses,hazard monitoring,natural resources exploration,etc.Generally,DEMs can be generated from various data sources,such as ground surveys,photogrammetric stereo methods,satellite images,laser scanning,and digitized contour lines.Compared with other data sources,contour lines are still the cheapest and more common data source becausethey cover all areas,at different scales,in most countries.Although there are different algorithms and technologies for interpolation in between contour lines,DEMs extracted solely from contours still suffer from poor terrain quality representation,which in turn negatively affects the quality of analytical applications results.In this paper,an approach for improving the digital terrain modeling based on contour line densification and Delaunay triangulation is presented to acquire a more suitable DEM for hydrographic modeling and its applications.The proposed methodology was tested using a variety of terrain patterns in terms of intensity:hilly,undulated,and plain(1:25,000 topographic map,5 m contour interval).The precision of the extracted GRID model increases as the number of added contours increases.Adding four contour lines,the Root Mean Square Error(RMSE)of examining points were 0.26 m,0.29 m,and 0.05 m for hilly,undulated,and plain samples,respectively,and the Mean Absolute Error(MAE)were 0.50 m,0.48 m,and 0.17 m.The convergence probabilities between extracted and original flow lines for the same regions were 96.91%,94.93%,and 84.03%.Applying the methodology,experimental results indicate that the developed approach provides a significant advantage in terrain modeling enhancement,generates DEMs smoothly and effectively from contours,mitigates problems and reduces uncertainties.展开更多
为同时满足覆盖与节能应用需求,本文提出了无线传感器网络中一种最小刚性拓扑控制算法MRTc(Minimal rigid topology control algorithm based on Voronoi coverage and Delaunay triangulation).该算法基于Voronoi覆盖机制,准确控制节...为同时满足覆盖与节能应用需求,本文提出了无线传感器网络中一种最小刚性拓扑控制算法MRTc(Minimal rigid topology control algorithm based on Voronoi coverage and Delaunay triangulation).该算法基于Voronoi覆盖机制,准确控制节点工作状态,实现活动节点对目标区域的完全覆盖.在此基础上,MRTc利用Delaunay三角剖分图的特点,构建出适用于无线传感器网络的最小刚性拓扑结构.该结构有效约束了网络平均节点度,且同时具有容错性、覆盖性和稀疏性.此外,MRTc引入节点功率控制策略,在维持网络完全覆盖的基础上最小化节点能耗.仿真结果进一步验证了本文提出的MRTc算法的有效性.展开更多
基金funded by National Natural Science Foundation of China(31570627)Hunan Forestry Science and Technology Project(XLK201740)+1 种基金Hunan Science and Technology Innovation Platform and Talent Plan(2017TP1022)Hunan Science and Technology Plan Project(2015WK3017)。
文摘It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spatial structure unit was generated based on the Delaunay triangulation model(DTM),and the weights were generated using the comprehensive values of the tree diameter at breast height,total height and crown width.The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates.Then,a weighted spatial pattern(WSP)was developed.After weighting,the neighboring trees were replaced,the replacement ratio was 38.3%,and there was 57.4%of the central tree.Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity(r=0.932)and randomness(r=0.711).The DTM method not only considers the spatial distance between trees,but also considers the non-spatial attributes of trees.By changing the spatial topological relation between trees,this method further improves the spatial structure measurement of forest.
基金funded by the Deanship of Scientific Research(DSR),King Abdulaziz University,Jeddah[Grant No.D 1441-298-137].
文摘Digital Elevation Models(DEMs)play a crucial role in civil and environmental applications,such as hydrologic and geologic analyses,hazard monitoring,natural resources exploration,etc.Generally,DEMs can be generated from various data sources,such as ground surveys,photogrammetric stereo methods,satellite images,laser scanning,and digitized contour lines.Compared with other data sources,contour lines are still the cheapest and more common data source becausethey cover all areas,at different scales,in most countries.Although there are different algorithms and technologies for interpolation in between contour lines,DEMs extracted solely from contours still suffer from poor terrain quality representation,which in turn negatively affects the quality of analytical applications results.In this paper,an approach for improving the digital terrain modeling based on contour line densification and Delaunay triangulation is presented to acquire a more suitable DEM for hydrographic modeling and its applications.The proposed methodology was tested using a variety of terrain patterns in terms of intensity:hilly,undulated,and plain(1:25,000 topographic map,5 m contour interval).The precision of the extracted GRID model increases as the number of added contours increases.Adding four contour lines,the Root Mean Square Error(RMSE)of examining points were 0.26 m,0.29 m,and 0.05 m for hilly,undulated,and plain samples,respectively,and the Mean Absolute Error(MAE)were 0.50 m,0.48 m,and 0.17 m.The convergence probabilities between extracted and original flow lines for the same regions were 96.91%,94.93%,and 84.03%.Applying the methodology,experimental results indicate that the developed approach provides a significant advantage in terrain modeling enhancement,generates DEMs smoothly and effectively from contours,mitigates problems and reduces uncertainties.
文摘为同时满足覆盖与节能应用需求,本文提出了无线传感器网络中一种最小刚性拓扑控制算法MRTc(Minimal rigid topology control algorithm based on Voronoi coverage and Delaunay triangulation).该算法基于Voronoi覆盖机制,准确控制节点工作状态,实现活动节点对目标区域的完全覆盖.在此基础上,MRTc利用Delaunay三角剖分图的特点,构建出适用于无线传感器网络的最小刚性拓扑结构.该结构有效约束了网络平均节点度,且同时具有容错性、覆盖性和稀疏性.此外,MRTc引入节点功率控制策略,在维持网络完全覆盖的基础上最小化节点能耗.仿真结果进一步验证了本文提出的MRTc算法的有效性.
