为了模拟河道洪水的淹没过程,开发了淹没信息的综合表达式。以哈尔滨城市防洪为例,建立了河道地形三角网的和网格拓扑关系,提出了堤防工程模拟的网格修正方法。运用水动力学模型计算水面线。采用左右三角形算法,实现淹没面搜索。基于三...为了模拟河道洪水的淹没过程,开发了淹没信息的综合表达式。以哈尔滨城市防洪为例,建立了河道地形三角网的和网格拓扑关系,提出了堤防工程模拟的网格修正方法。运用水动力学模型计算水面线。采用左右三角形算法,实现淹没面搜索。基于三维图形引擎Open Scene Graph,建立了研究区域的三维虚拟环境。实现了将地理环境、洪水淹没区域、淹没程度与水深分布等多种信息的三维虚拟环境的综合表现。因而,该成果可用于洪水预报。展开更多
The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data o...The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data originating from Change＇E-1 CCD stereo camera, three automatic extraction methods for the impact craters are implemented in two research areas： direct extraction from flooded DEM data （the Flooded method）, object-oriented extraction from DEM data by using ENVI ZOOM function （the Object-Oriented method） and novel object-oriented extraction from flooded DEM data （the Flooded Object-Oriented method）. Accuracy assessment, extracted degree computation, cumulative frequency analysis, shape and age analysis of the extracted craters combined display the following results. （1） The Flooded Object-Oriented method yields better accuracy than the other two methods in the two research areas; the extraction result of the Flooded method offers the similar accuracy to that of the Object-Oriented method. （2） The cumulative frequency curves for the extracted craters and the confirmed craters share a simi- lar change trajectory. （3） The number of the impact craters extracted by the three methods in the Imbrian period is the largest and is of various types; as to their age earlier than lmbrain, it is difficult to extract because they could have been destroyed.展开更多
文摘为了模拟河道洪水的淹没过程,开发了淹没信息的综合表达式。以哈尔滨城市防洪为例,建立了河道地形三角网的和网格拓扑关系,提出了堤防工程模拟的网格修正方法。运用水动力学模型计算水面线。采用左右三角形算法,实现淹没面搜索。基于三维图形引擎Open Scene Graph,建立了研究区域的三维虚拟环境。实现了将地理环境、洪水淹没区域、淹没程度与水深分布等多种信息的三维虚拟环境的综合表现。因而,该成果可用于洪水预报。
基金supported by the National Natural Science Foundation of China (Grant Nos. 40871177 and 41171332)the Knowledge Innovation Project of the Institute of Geographic and Natural Resources Research, the Chinese Academy of Sci-ences (Grant No. 201001005)
文摘The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data originating from Change＇E-1 CCD stereo camera, three automatic extraction methods for the impact craters are implemented in two research areas： direct extraction from flooded DEM data （the Flooded method）, object-oriented extraction from DEM data by using ENVI ZOOM function （the Object-Oriented method） and novel object-oriented extraction from flooded DEM data （the Flooded Object-Oriented method）. Accuracy assessment, extracted degree computation, cumulative frequency analysis, shape and age analysis of the extracted craters combined display the following results. （1） The Flooded Object-Oriented method yields better accuracy than the other two methods in the two research areas; the extraction result of the Flooded method offers the similar accuracy to that of the Object-Oriented method. （2） The cumulative frequency curves for the extracted craters and the confirmed craters share a simi- lar change trajectory. （3） The number of the impact craters extracted by the three methods in the Imbrian period is the largest and is of various types; as to their age earlier than lmbrain, it is difficult to extract because they could have been destroyed.
