A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effecti...A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.展开更多
Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of eleva...Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.展开更多
To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwat...To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation（LSE） is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.展开更多
This paper describes the erosion procedure of the natural terrain and deduces the two main physical physical procedures by the hydraulic erosion and thermal weathering. through a large number of iteration calculation ...This paper describes the erosion procedure of the natural terrain and deduces the two main physical physical procedures by the hydraulic erosion and thermal weathering. through a large number of iteration calculation ,the action procedure could be expressed and its realistic graphics could be displayed.展开更多
中国气象局乌鲁木齐沙漠气象研究所自2017年开始推进中亚区域快速更新多尺度分析和预报系统RMAPS-CA的研发工作,并在多源资料联合同化技术、参数化方案优化和动力框架调整方面取得了一定的研究成果。在回顾RMAPS-CA业务研发历程的基础上...中国气象局乌鲁木齐沙漠气象研究所自2017年开始推进中亚区域快速更新多尺度分析和预报系统RMAPS-CA的研发工作,并在多源资料联合同化技术、参数化方案优化和动力框架调整方面取得了一定的研究成果。在回顾RMAPS-CA业务研发历程的基础上,重点对雷达反射率同化、高空次网格地形重力波拖曳与近地层阻塞拖曳分离的次网格物理过程、混合地形追随坐标动力框架以及基于贝叶斯模式平均(Bayesian Model Averaging,BMA)方法订正预报产品等方面所取得的研究成果进行综述。针对中亚地区常规观测稀疏且沙漠下垫面范围广等特点,从卫星地面通道同化等方面提出了加强中亚区域数值天气预报业务研发及应用的建议。展开更多
随着科技的快速发展,无人机(Unmanned Aerial Vehicle,UAV)高精度地形测绘技术已成为现代测绘领域的重要组成部分。该技术融合无人机平台、高精度传感器、图像处理、地理信息系统(Geographic Information Systems,GIS)等多种技术手段,...随着科技的快速发展,无人机(Unmanned Aerial Vehicle,UAV)高精度地形测绘技术已成为现代测绘领域的重要组成部分。该技术融合无人机平台、高精度传感器、图像处理、地理信息系统(Geographic Information Systems,GIS)等多种技术手段,实现对复杂地形地貌的高效精准测绘,具有重要的应用价值。基于此,文章探讨无人机高精度地形测绘的特点、数据处理技术的应用措施,并通过具体案例分析其在实际应用中的效果,为推动相关技术的发展提供参考。展开更多
文摘A new method for constructing contours from complicated terrain elevation grids containing invalid data is put forward. By using this method, the topological consistency of contours in groups can be maintained effectively and the contours can be drawn smoothly based on boundaries pre-searching and local correction. An experimental example is given to demonstrate that the contours constructed by this method are of good quality.
基金Supported by the National Natural Science Foundation of China(61363075)the National High Technology Research and Development Program of China(863 Program)(2012AA12A308)the Yue Qi Young Scholars Program of China University of Mining&Technology,Beijing(800015Z1117)
文摘Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51179035 and 51279221)the Natural Science Foundation of Heilongjiang Province(Grant No.E201121)
文摘To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation（LSE） is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.
文摘This paper describes the erosion procedure of the natural terrain and deduces the two main physical physical procedures by the hydraulic erosion and thermal weathering. through a large number of iteration calculation ,the action procedure could be expressed and its realistic graphics could be displayed.
文摘中国气象局乌鲁木齐沙漠气象研究所自2017年开始推进中亚区域快速更新多尺度分析和预报系统RMAPS-CA的研发工作,并在多源资料联合同化技术、参数化方案优化和动力框架调整方面取得了一定的研究成果。在回顾RMAPS-CA业务研发历程的基础上,重点对雷达反射率同化、高空次网格地形重力波拖曳与近地层阻塞拖曳分离的次网格物理过程、混合地形追随坐标动力框架以及基于贝叶斯模式平均(Bayesian Model Averaging,BMA)方法订正预报产品等方面所取得的研究成果进行综述。针对中亚地区常规观测稀疏且沙漠下垫面范围广等特点,从卫星地面通道同化等方面提出了加强中亚区域数值天气预报业务研发及应用的建议。
文摘探究砒砂岩区的土壤质量状况,对于改善该区生态环境、指导人工林培育及可持续发展具有重要意义。本研究以不同地形的土壤作为研究对象,测定了16项土壤理化性质指标,运用主成分分析法(Principal component analysis,PCA)构建了土壤质量评价的最小数据集(Minimum data set,MDS),通过线性函数法(SL)、非线性函数法(SNL)对全数据集(Total data set,TDS)进行指标归一化处理,分别进行全数据集和最小数据集的土壤质量指数(Soil quality index,SQI)计算,对不同地形的砒砂岩区土壤质量进行了评价。结果表明:(1)砒砂岩的土壤养分含量偏低,其平均水平仅仅达到5级(贫瘠)的水准;(2)砒砂岩区土壤质量评价的最小数据集由土壤厚度、全磷、粉粒、砂粒、含水率和碱解氮构成,可以解释全数据集72.586%的信息;(3)研究区土壤质量指数均值为0.373,处于中等偏低水平,其中阴坡>阳坡,平坡>缓坡>斜坡>陡坡。本研究为砒砂岩区土壤质量诊断及选择合理的管理措施提供理论依据。
文摘随着科技的快速发展,无人机(Unmanned Aerial Vehicle,UAV)高精度地形测绘技术已成为现代测绘领域的重要组成部分。该技术融合无人机平台、高精度传感器、图像处理、地理信息系统(Geographic Information Systems,GIS)等多种技术手段,实现对复杂地形地貌的高效精准测绘,具有重要的应用价值。基于此,文章探讨无人机高精度地形测绘的特点、数据处理技术的应用措施,并通过具体案例分析其在实际应用中的效果,为推动相关技术的发展提供参考。
