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北斗GEO/IGSO/MEO卫星定轨地面站构型影响分析及其优化 被引量:13
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作者 张龙平 党亚民 +3 位作者 成英燕 薛树强 谷守周 韩德强 《测绘学报》 CSCD 北大核心 2016年第S2期82-92,共11页
GNSS卫星定轨精度主要取决于卫星动力学模型精度和GNSS几何观测信息。由于北斗GEO/IGSO卫星静地、高轨特性,以及力学模型不精确等原因,地面几何观测信息对轨道改进至关重要。本文讨论了北斗GEO/IGSO/MEO卫星定轨地面站分布影响及优化改... GNSS卫星定轨精度主要取决于卫星动力学模型精度和GNSS几何观测信息。由于北斗GEO/IGSO卫星静地、高轨特性,以及力学模型不精确等原因,地面几何观测信息对轨道改进至关重要。本文讨论了北斗GEO/IGSO/MEO卫星定轨地面站分布影响及优化改进方法。在简化动力学定轨模型基础上,探讨多历元几何观测信息累积对轨道的改进;研究了北斗导航卫星定轨理想几何构型条件,得到影响定轨精度的几何因子,包括测站数量、覆盖范围、分布密度;利用离散概率密度方法研究地面站构型,分析了3类卫星轨道改进机理和优化方法。通过算例,讨论了增加5个中国区域基准站改善离散概率密度指标,优化全球北斗卫星定轨构型,发现GEO和IGSO卫星精度改善最为明显,MEO卫星改善最小;其中GEO卫星提高了10%,IGSO卫星提高了16%,MEO卫星提高了4%。 展开更多
关键词 虚拟跟踪站 构型优化 离散概率密度 构型叠加
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Robust background subtraction in traffic video sequence 被引量:6
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作者 高韬 刘正光 +3 位作者 岳士弘 张军 梅建强 高文春 《Journal of Central South University》 SCIE EI CAS 2010年第1期187-195,共9页
For intelligent transportation surveillance, a novel background model based on Mart wavelet kernel and a background subtraction technique based on binary discrete wavelet transforms were introduced. The background mod... For intelligent transportation surveillance, a novel background model based on Mart wavelet kernel and a background subtraction technique based on binary discrete wavelet transforms were introduced. The background model kept a sample of intensity values for each pixel in the image and used this sample to estimate the probability density function of the pixel intensity. The density function was estimated using a new Marr wavelet kernel density estimation technique. Since this approach was quite general, the model could approximate any distribution for the pixel intensity without any assumptions about the underlying distribution shape. The background and current frame were transformed in the binary discrete wavelet domain, and background subtraction was performed in each sub-band. After obtaining the foreground, shadow was eliminated by an edge detection method. Experimental results show that the proposed method produces good results with much lower computational complexity and effectively extracts the moving objects with accuracy ratio higher than 90%, indicating that the proposed method is an effective algorithm for intelligent transportation system. 展开更多
关键词 background modeling background subtraction Marr wavelet binary discrete wavelet transform shadow elimination
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