With continuous expansion of satellite applications,the requirements for satellite communication services,such as communication delay,transmission bandwidth,transmission power consumption,and communication coverage,ar...With continuous expansion of satellite applications,the requirements for satellite communication services,such as communication delay,transmission bandwidth,transmission power consumption,and communication coverage,are becoming higher.This paper first presents an overview of the current development status of Low Earth Orbit(LEO)satellite constellations,and then conducts a demand analysis for multi-satellite data transmission based on LEO satellite constellations.The problem is described,and the challenges and difficulties of the problem are analyzed accordingly.On this basis,a multi-satellite data-transmission mathematical model is then constructed.Combining classical heuristic allocating strategies on the features of the proposed model,with the reinforcement learning algorithm Deep Q-Network(DQN),a two-stage optimization framework based on heuristic and DQN is proposed.Finally,by taking into account the spatial and temporal distribution characteristics of satellite and facility resources,a multi-satellite scheduling instance dataset is generated.Experimental results validate the rationality and correctness of the DQN algorithm in solving the collaborative scheduling problem of multi-satellite data transmission.展开更多
This study proposes a virtual globe-based vector data model named the quaternary quadrangle vector tile model(QQVTM)in order to better manage,visualize,and analyze massive amounts of global multi-scale vector data.The...This study proposes a virtual globe-based vector data model named the quaternary quadrangle vector tile model(QQVTM)in order to better manage,visualize,and analyze massive amounts of global multi-scale vector data.The model integrates the quaternary quadrangle mesh(a discrete global grid system)and global image,terrain,and vector data.A QQVTM-based organization method is presented to organize global multi-scale vector data,including linear and polygonal vector data.In addition,tilebased reconstruction algorithms are designed to search and stitch the vector fragments scattered in tiles to reconstruct and store the entire vector geometries to support vector query and 3D analysis of global datasets.These organized vector data are in turn visualized and queried using a geometry-based approach.Our experimental results demonstrate that the QQVTM can satisfy the requirements for global vector data organization,visualization,and querying.Moreover,the QQVTM performs better than unorganized 2D vectors regarding rendering efficiency and better than the latitude–longitude-based approach regarding data redundancy.展开更多
The scene-rendering mechanism based on binocular vision is one of the key techniques for the VR globe to achieve immersion-type visualization of global 3D scenes.However,this special rendering mechanism also requires ...The scene-rendering mechanism based on binocular vision is one of the key techniques for the VR globe to achieve immersion-type visualization of global 3D scenes.However,this special rendering mechanism also requires that the 3D scene is continuously drawn twice within one frame,which significantly affects the rendering efficiency of VR globes.Therefore,we propose a binocular parallel rendering method.This method first improves the current rendering process of VR globes by assigning the rendering tasks for the left and right camera of VR to be processed on different CPU cores,thereby achieving parallel rendering of binocular scenes.Second,due to the problem of inconsistent resolution of binocular scenes caused by different viewpoints for the left and right cameras,we propose a resolution synchronize algorithm.this algorithm conducts realtime synchronization on the resolution of scene in the rendering process and thus avoids the problem of erroneous binocular stereo matching.Finally,we validate the effectiveness of the method in this paper through experiments.The results of experiments indicate that while the method in this paper can ensure the consistency of binocular scene resolution,it can decrease the frame time of VR globes by approximately 27%on average.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42271391,62006214,and 42101439)the Joint Funds of Equipment Pre-Research and Ministry of Education of China(No.8091B022148)+1 种基金the 14th Five-Year Pre-Research Project of Civil Aerospace of China,the Hubei Excellent Young and Middle-Aged Science and Technology Innovation Team Plan Project(No.T2021031)the Open Research Project of Hubei Key Laboratory of Intelligent GeoInformation Processing(No.KLIGIP-2022-B09).
文摘With continuous expansion of satellite applications,the requirements for satellite communication services,such as communication delay,transmission bandwidth,transmission power consumption,and communication coverage,are becoming higher.This paper first presents an overview of the current development status of Low Earth Orbit(LEO)satellite constellations,and then conducts a demand analysis for multi-satellite data transmission based on LEO satellite constellations.The problem is described,and the challenges and difficulties of the problem are analyzed accordingly.On this basis,a multi-satellite data-transmission mathematical model is then constructed.Combining classical heuristic allocating strategies on the features of the proposed model,with the reinforcement learning algorithm Deep Q-Network(DQN),a two-stage optimization framework based on heuristic and DQN is proposed.Finally,by taking into account the spatial and temporal distribution characteristics of satellite and facility resources,a multi-satellite scheduling instance dataset is generated.Experimental results validate the rationality and correctness of the DQN algorithm in solving the collaborative scheduling problem of multi-satellite data transmission.
基金the National Natural Science Foundation of China[grant number 41171314],[grant number 41023001]the Fundamental Research Funds for the Central Universities[grant number 2014619020203].Comments from the anonymous reviewers and editor are appreciated.
文摘This study proposes a virtual globe-based vector data model named the quaternary quadrangle vector tile model(QQVTM)in order to better manage,visualize,and analyze massive amounts of global multi-scale vector data.The model integrates the quaternary quadrangle mesh(a discrete global grid system)and global image,terrain,and vector data.A QQVTM-based organization method is presented to organize global multi-scale vector data,including linear and polygonal vector data.In addition,tilebased reconstruction algorithms are designed to search and stitch the vector fragments scattered in tiles to reconstruct and store the entire vector geometries to support vector query and 3D analysis of global datasets.These organized vector data are in turn visualized and queried using a geometry-based approach.Our experimental results demonstrate that the QQVTM can satisfy the requirements for global vector data organization,visualization,and querying.Moreover,the QQVTM performs better than unorganized 2D vectors regarding rendering efficiency and better than the latitude–longitude-based approach regarding data redundancy.
基金The Nature Science Foundation Innovation Group Project of Hubei Province,China[grant number 2016CFA003].
文摘The scene-rendering mechanism based on binocular vision is one of the key techniques for the VR globe to achieve immersion-type visualization of global 3D scenes.However,this special rendering mechanism also requires that the 3D scene is continuously drawn twice within one frame,which significantly affects the rendering efficiency of VR globes.Therefore,we propose a binocular parallel rendering method.This method first improves the current rendering process of VR globes by assigning the rendering tasks for the left and right camera of VR to be processed on different CPU cores,thereby achieving parallel rendering of binocular scenes.Second,due to the problem of inconsistent resolution of binocular scenes caused by different viewpoints for the left and right cameras,we propose a resolution synchronize algorithm.this algorithm conducts realtime synchronization on the resolution of scene in the rendering process and thus avoids the problem of erroneous binocular stereo matching.Finally,we validate the effectiveness of the method in this paper through experiments.The results of experiments indicate that while the method in this paper can ensure the consistency of binocular scene resolution,it can decrease the frame time of VR globes by approximately 27%on average.
