Sphere model is the research hotspot in the GIS domain presently. It has become a strong integrated platform of spatial information with its strong abilities of spatial data management and visualization. Based on Skyl...Sphere model is the research hotspot in the GIS domain presently. It has become a strong integrated platform of spatial information with its strong abilities of spatial data management and visualization. Based on Skyline software, this paper introduces the framework, functions and technical method of realization of visual digital ocean system. The practice proves that the system has a good future in marine information visualization and sharing.展开更多
To solve the inaccuracy problem caused by the two existing methods (averageend-area method and prismoidal method) used for the calculation of roadway earthwork volume, thispaper puts forward a new concept of the 3-dim...To solve the inaccuracy problem caused by the two existing methods (averageend-area method and prismoidal method) used for the calculation of roadway earthwork volume, thispaper puts forward a new concept of the 3-dimensional algorithm that takes all the roadway geometricdesign procedures as a kind of geometrical operation between the ground model (original terrainmodel) and the roadway model (designed model) under certain constraints, and then presents acomplete 3-dimensional algorithm of roadway earthwork volume as well as its executable computerprogram. The algorithm benefits from the re-triangulation technique of constrained delaunaytriangulation (CDT), which can yield a true volume value theoretically. Through a number ofpractical testscovering varied intervals between adjacent cross sections, it is proven to possess ahigher accuracy compared with that of traditional methods. All the work involved in this paperindicates that the 3-dimensional calculation of roadway earthwork volumeis feasible, more accurateand should have further application in practice.展开更多
On the basis of the study on road elements and th e existing three-dimensional road data models, this paper puts forward the transe ct-based road modeling, resolves the modeling of the simplest road with two roa d tra...On the basis of the study on road elements and th e existing three-dimensional road data models, this paper puts forward the transe ct-based road modeling, resolves the modeling of the simplest road with two roa d transects, and fulfils the visualization of the road. OpenGL is applied as the tool of visualization. The map texture technology, LOD algorithm and dynamic mu lti-differentiating texture technology are of benefit to the construction of 3D road GIS, and improve the speed of roaming and effective visualization. This pa per also disusses the combination of 2D digitall road map and 3D road scene, and the dynamic response between them. Finally, on the basis of the research on the transect-based road model, this paper develops the three-dimensional road geo graphic information system called virtual road ( VRoad ), which not only suppli es road designers with a set of tool which can turn the designed 2D road data in to 3D road and the high road assistant function area in computer, but also suppl ies the road management with a set of tool which can realize the road real time and interactive roaming, high-efficiency management.展开更多
A vegetation evolution model influenced by a degeneration of soil ecological functions was set up. Three ideal communities of a) trees, b) shrubs, and c) herbage populations were first simulated. Then numerical simula...A vegetation evolution model influenced by a degeneration of soil ecological functions was set up. Three ideal communities of a) trees, b) shrubs, and c) herbage populations were first simulated. Then numerical simulations of the evolutionary and developmental processes of a natural forest community, which is composed of over 100 species,were conducted. Results of the study showed that a) in all communities, soil degeneration not only drove some weaker species to extinction, but also a few dominant ones; b) there were different response scales with species in an ideal tree metapopulation that could persist as long as a thousand years, with shrubs in an ideal shrub metapopulation that could persevere for several hundred years, and with species in an ideal herbage metapopulation that could become extinct within 10 years; and c) each metapopulation experienced three evolutionary stages during adaptation to the environment: a) the stage of compelled adaptation or resistance, b) the adjusted stage, and c) the stabilized stage.展开更多
Synthetic aperture radar interferometry (InSAR) has been used as an innovative technique for digital elevation model (DEM) and topographic map generation. In this paper, external DEMs are used for InSAR DEM generation...Synthetic aperture radar interferometry (InSAR) has been used as an innovative technique for digital elevation model (DEM) and topographic map generation. In this paper, external DEMs are used for InSAR DEM generation to reduce the errors in data processing. The DEMs generated from repeat-pass InSAR are compared. For steep slopes and severe changes in topography, phase unwrapping quality can be improved by subtracting the phase calculated from an external DEM. It is affirmative that the absolute height accuracy of the InSAR DEM is improved by using external DEM. The data processing was undertaken without the use of ground control points and other manual operation.展开更多
In photogrammetry and remote sensing, image matching is a basic and crucial process for automatic DEM generation. In this paper we presented a image relaxation matching method based on feature points. This method can ...In photogrammetry and remote sensing, image matching is a basic and crucial process for automatic DEM generation. In this paper we presented a image relaxation matching method based on feature points. This method can be considered as an extention of regular grid point based matching. It avoids the shortcome of grid point based matching. For example, with this method, we can avoid low or even no texture area where errors frequently appear in cross correlaton matching. In the mean while, it makes full use of some mature techniques such as probability relaxation, image pyramid and the like which have already been successfully used in grid point matching process. Application of the technique to DEM generaton in different regions proved that it is more reasonable and reliable.展开更多
A new method to reconstruct a comparatively complete muscle model of the human lower limb from CT and MRI data is presented. Topological structure of more than fourteen muscles is built and coordinates of origin and i...A new method to reconstruct a comparatively complete muscle model of the human lower limb from CT and MRI data is presented. Topological structure of more than fourteen muscles is built and coordinates of origin and insertion points are given. Based on this model, straight-line model and centroid-line muscle model are acquired. Muscle force prediction is discussed according to the model reconstructed, and a multi-objective optimization method is put forward for evaluating muscle forces of the human lower extremity.展开更多
This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D ...This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D visualization based on GIS, then discusses the method of constructing 3D visual digital model, and then introduces the terrain digital technology, feature modeling technology. Finally, the technical route shows that this method has good practicability.展开更多
This paper develops a method which can be used to assist aerial navigation by determining the spatial position and posture of the aerial photographic plane. After the method, aerial images match known DEM to capture t...This paper develops a method which can be used to assist aerial navigation by determining the spatial position and posture of the aerial photographic plane. After the method, aerial images match known DEM to capture the spatial position and posture. Some aerial images and terrain data are used to testify our method. Compared with those of analytic and stereo mappers, the results by our method are correspondent to real measurements well.展开更多
Sub-tidal barotropic current variations coupled with residual sea level fluctuation in the Bohai and Yellow Seas during wintertime are addressed in this study.The temporal evolution and spatial distribution of current...Sub-tidal barotropic current variations coupled with residual sea level fluctuation in the Bohai and Yellow Seas during wintertime are addressed in this study.The temporal evolution and spatial distribution of current fluctuation are investigated using moored acoustic Doppler current profiler data in a three-dimensional numerical model.It is found that a southward current followed by a northward current occurred in the northern Yellow Sea during the fluctuation,concurrent with a significant outflow followed by inflow through the Bohai Strait.The process is consistent from surface to bottom and is coupled with remarkable residual sea level fluctuation.This quasi three-day fluctuation with amplitude 0.2-0.3 m/s leads to 1 m/1.2 m drawdown in the northern Yellow and Bohai Seas,respectively,strongly influencing water exchange between those seas.Because this a prominent feature in the seas,it is necessary to evaluate its effect on fluctuation during winter in future studies,in particular,the northward current during the recovery phase of sea level in the Bohai and Yellow Seas regarding seasonal variation.展开更多
Climate change will lead to a significant alteration in the temporal and spatial pattern variation in the regional hydrological cycle, and the subsequent lack of water, environmental deterioration, floods and droughts...Climate change will lead to a significant alteration in the temporal and spatial pattern variation in the regional hydrological cycle, and the subsequent lack of water, environmental deterioration, floods and droughts etc. And it is especially remarkable in semi-humid and semi-arid region. In this paper, the impacts of climate change on the hydrological cycle were analyzed for the Hai River Basin, a semi-humid and semi-arid basin and also the water receiving area of the middle route of South-to-North Water Diversion project. Meanwhile it is the most vulnerable to climate change. Firstly, the linear regression and Mann-Kendall non-parametric test methods were used to analyze the change characteristics of the hydrological and meteorological elements for the period from 1960 to 2009. The results show a significant increase in temperature, while precipitation decreases slightly, and runoff decreases drastically over the past 50 years. Secondly, the applicability of SWAT （Soil and Water Assessment Tool） model based on the DEM （Digital Elevation Model）, land use and soil type was verified in the basin. Results show the model performs well in this basin. Furthermore, the water balance model, Fu＇s theory and Koichiro＇s theory were used to calculate the actual evaporation, comparing to the simulated actual evaporation by SWAT model to validate the result for the lack of large-scale observed evaporation datasets. Possible reasons were also analyzed to explore the reasonable factor for the decline of the runoff. Finally the precipitation, temperature, runoff and evaporation response processes based on the IPCC AR4 multi-mode climate models and the verified SWAT model under different GHG emission scenarios （SRES-A2, AIB and B1） in the 21st century were discussed in three time periods： 2020s （2011-2040）, 20S0s （2041-2070）, 2080s （2071-2099）. Results show that there are systematic positive trends for precipitation and temperature while the trends for runoff and evaporation will differ among sub-areas. The results will offer some references for adaptive water management in a changing environment, also including adaptation of a cross-basin water transfer project.展开更多
基金supported by State Oceanic Administration "908" Program (908-03)State Oceanic Administration Funds for Young Scholar (No. 2009609)
文摘Sphere model is the research hotspot in the GIS domain presently. It has become a strong integrated platform of spatial information with its strong abilities of spatial data management and visualization. Based on Skyline software, this paper introduces the framework, functions and technical method of realization of visual digital ocean system. The practice proves that the system has a good future in marine information visualization and sharing.
文摘To solve the inaccuracy problem caused by the two existing methods (averageend-area method and prismoidal method) used for the calculation of roadway earthwork volume, thispaper puts forward a new concept of the 3-dimensional algorithm that takes all the roadway geometricdesign procedures as a kind of geometrical operation between the ground model (original terrainmodel) and the roadway model (designed model) under certain constraints, and then presents acomplete 3-dimensional algorithm of roadway earthwork volume as well as its executable computerprogram. The algorithm benefits from the re-triangulation technique of constrained delaunaytriangulation (CDT), which can yield a true volume value theoretically. Through a number ofpractical testscovering varied intervals between adjacent cross sections, it is proven to possess ahigher accuracy compared with that of traditional methods. All the work involved in this paperindicates that the 3-dimensional calculation of roadway earthwork volumeis feasible, more accurateand should have further application in practice.
基金FundedbythegrantsfromHubeiprovincetechnologyprojectoftacklekeyproblem (No .2 0 0 1AA1 0 4A01)andJilinprovinceacademyofroadsurveyinganddesign
文摘On the basis of the study on road elements and th e existing three-dimensional road data models, this paper puts forward the transe ct-based road modeling, resolves the modeling of the simplest road with two roa d transects, and fulfils the visualization of the road. OpenGL is applied as the tool of visualization. The map texture technology, LOD algorithm and dynamic mu lti-differentiating texture technology are of benefit to the construction of 3D road GIS, and improve the speed of roaming and effective visualization. This pa per also disusses the combination of 2D digitall road map and 3D road scene, and the dynamic response between them. Finally, on the basis of the research on the transect-based road model, this paper develops the three-dimensional road geo graphic information system called virtual road ( VRoad ), which not only suppli es road designers with a set of tool which can turn the designed 2D road data in to 3D road and the high road assistant function area in computer, but also suppl ies the road management with a set of tool which can realize the road real time and interactive roaming, high-efficiency management.
基金Project supported by the National Natural Science Foundation of China (No. 40371108) the National "211" Key Project of China: The environmental evolution and ecological construction on multi-spatio-temporal scales.
文摘A vegetation evolution model influenced by a degeneration of soil ecological functions was set up. Three ideal communities of a) trees, b) shrubs, and c) herbage populations were first simulated. Then numerical simulations of the evolutionary and developmental processes of a natural forest community, which is composed of over 100 species,were conducted. Results of the study showed that a) in all communities, soil degeneration not only drove some weaker species to extinction, but also a few dominant ones; b) there were different response scales with species in an ideal tree metapopulation that could persist as long as a thousand years, with shrubs in an ideal shrub metapopulation that could persevere for several hundred years, and with species in an ideal herbage metapopulation that could become extinct within 10 years; and c) each metapopulation experienced three evolutionary stages during adaptation to the environment: a) the stage of compelled adaptation or resistance, b) the adjusted stage, and c) the stabilized stage.
基金Funded by the Key Tenth five Project of State Bureau of Surveying and Mapping (No. 1469990324236 04 06) and the Faculty Research Grant of Uni versity of New South Wales (No. PS03283).
文摘Synthetic aperture radar interferometry (InSAR) has been used as an innovative technique for digital elevation model (DEM) and topographic map generation. In this paper, external DEMs are used for InSAR DEM generation to reduce the errors in data processing. The DEMs generated from repeat-pass InSAR are compared. For steep slopes and severe changes in topography, phase unwrapping quality can be improved by subtracting the phase calculated from an external DEM. It is affirmative that the absolute height accuracy of the InSAR DEM is improved by using external DEM. The data processing was undertaken without the use of ground control points and other manual operation.
文摘In photogrammetry and remote sensing, image matching is a basic and crucial process for automatic DEM generation. In this paper we presented a image relaxation matching method based on feature points. This method can be considered as an extention of regular grid point based matching. It avoids the shortcome of grid point based matching. For example, with this method, we can avoid low or even no texture area where errors frequently appear in cross correlaton matching. In the mean while, it makes full use of some mature techniques such as probability relaxation, image pyramid and the like which have already been successfully used in grid point matching process. Application of the technique to DEM generaton in different regions proved that it is more reasonable and reliable.
文摘A new method to reconstruct a comparatively complete muscle model of the human lower limb from CT and MRI data is presented. Topological structure of more than fourteen muscles is built and coordinates of origin and insertion points are given. Based on this model, straight-line model and centroid-line muscle model are acquired. Muscle force prediction is discussed according to the model reconstructed, and a multi-objective optimization method is put forward for evaluating muscle forces of the human lower extremity.
文摘This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D visualization based on GIS, then discusses the method of constructing 3D visual digital model, and then introduces the terrain digital technology, feature modeling technology. Finally, the technical route shows that this method has good practicability.
基金uisition of Directional Funded by the National 973 Project (No.2003CB415205).
文摘This paper develops a method which can be used to assist aerial navigation by determining the spatial position and posture of the aerial photographic plane. After the method, aerial images match known DEM to capture the spatial position and posture. Some aerial images and terrain data are used to testify our method. Compared with those of analytic and stereo mappers, the results by our method are correspondent to real measurements well.
基金Supported by the National Natural Science Foundation of China(Nos.41430963,41276013)
文摘Sub-tidal barotropic current variations coupled with residual sea level fluctuation in the Bohai and Yellow Seas during wintertime are addressed in this study.The temporal evolution and spatial distribution of current fluctuation are investigated using moored acoustic Doppler current profiler data in a three-dimensional numerical model.It is found that a southward current followed by a northward current occurred in the northern Yellow Sea during the fluctuation,concurrent with a significant outflow followed by inflow through the Bohai Strait.The process is consistent from surface to bottom and is coupled with remarkable residual sea level fluctuation.This quasi three-day fluctuation with amplitude 0.2-0.3 m/s leads to 1 m/1.2 m drawdown in the northern Yellow and Bohai Seas,respectively,strongly influencing water exchange between those seas.Because this a prominent feature in the seas,it is necessary to evaluate its effect on fluctuation during winter in future studies,in particular,the northward current during the recovery phase of sea level in the Bohai and Yellow Seas regarding seasonal variation.
基金supported by National Basic Research Program of China(2010CB428406)the National Natural Science Foundation of China (No. 41071025/40730632)MWR Commonweal Project (200801001)
文摘Climate change will lead to a significant alteration in the temporal and spatial pattern variation in the regional hydrological cycle, and the subsequent lack of water, environmental deterioration, floods and droughts etc. And it is especially remarkable in semi-humid and semi-arid region. In this paper, the impacts of climate change on the hydrological cycle were analyzed for the Hai River Basin, a semi-humid and semi-arid basin and also the water receiving area of the middle route of South-to-North Water Diversion project. Meanwhile it is the most vulnerable to climate change. Firstly, the linear regression and Mann-Kendall non-parametric test methods were used to analyze the change characteristics of the hydrological and meteorological elements for the period from 1960 to 2009. The results show a significant increase in temperature, while precipitation decreases slightly, and runoff decreases drastically over the past 50 years. Secondly, the applicability of SWAT （Soil and Water Assessment Tool） model based on the DEM （Digital Elevation Model）, land use and soil type was verified in the basin. Results show the model performs well in this basin. Furthermore, the water balance model, Fu＇s theory and Koichiro＇s theory were used to calculate the actual evaporation, comparing to the simulated actual evaporation by SWAT model to validate the result for the lack of large-scale observed evaporation datasets. Possible reasons were also analyzed to explore the reasonable factor for the decline of the runoff. Finally the precipitation, temperature, runoff and evaporation response processes based on the IPCC AR4 multi-mode climate models and the verified SWAT model under different GHG emission scenarios （SRES-A2, AIB and B1） in the 21st century were discussed in three time periods： 2020s （2011-2040）, 20S0s （2041-2070）, 2080s （2071-2099）. Results show that there are systematic positive trends for precipitation and temperature while the trends for runoff and evaporation will differ among sub-areas. The results will offer some references for adaptive water management in a changing environment, also including adaptation of a cross-basin water transfer project.
