低空摄影测量立体影像匹配的现状与展望

影像匹配是在两幅或多幅具有重叠度的影像中通过特定的算法提取影像间同名点的过程,是低空摄影测量数据处理中最为关键的步骤,匹配质量与效率直接影响到后续数据处理的成功与否,关系到测绘产品生成质量。本文系统阐述了低空摄影测量影像匹配的研究现状与展望。对影像匹配的分类进行总结和归纳,大体上,影像匹配可划分为两大类,即基于灰度和基于特征的匹配。重点针对基于特征的影像匹配,从点、线、面等特征提取算法及特征描述符和相似性测度与策略等方面进行了详细阐述。此外,列举最新的基于深度学习的影像匹配算法,对低空平台搭载的多样化传感器数据融合可能涉及的影像匹配方法进行了展望。     

指导工程测量竞赛经验探讨

技能竞赛的蓬勃发展为加强技能人才培养、选拔和促进优秀人才脱颖而出发挥了重要作用。通过对全国和北京市测绘地理信息行业职业技能竞赛工程测量赛项设置、技术要求、竞赛特点的归纳分析,从参赛队员的选拔、竞赛训练方案、技战术、比赛注意事项等方面对竞赛工作进行探讨,为今后的备赛以及参赛提供借鉴。     

基于正交匹配追踪的声层析方法

声速剖面的变化会对声传播产生较大的影响,经验正交函数模型经常用来实现对声速剖面数据的简化描述。然而在内波、湍流等海水不均匀性存在时,这种正则化操作会造成声速重构精度的大幅降低。本文利用字典学习生成声速剖面的非正交原子,在稀疏编码时采用正交匹配追踪（OMP,Orthogonal Matching Pursuit）算法,更新字典则使用KSVD （Kernel Singular Value Decomposition）的字典更新算法。由于字典学习不需要强制使用正交条件,对于训练数据更加灵活,从而可以使用少数的原子组合达到更高的重构精度。利用一次浅海声学实验多次测量的声速剖面研究了海水声速剖面的经验正交函数表示和字典学习,研究表明：相比于正交函数表示,学习字典可以利用少数原子（甚至一个原子）更好的解释声速剖面扰动。字典学习可以提高声速剖面的稀疏性,从而提高声速剖面的反演精度。     

利用半参数模型估计确定验潮组网的深度基准面

深度基准面的确定是进行海洋测量的基础,准确确定深度基准面是进行海洋测量的有效前提。提出了一种将CORS技术与验潮组网技术进行结合的新传递深度基准面的方法,实现长、短期验潮站同步验潮实现深度基准面的增强传递;提出了采用半参数模型理论来求取潮差比的计算方法;具体阐述了验潮组网通过间接平差求取短期验潮站的深度基准面的计算方法,减少了验潮测量的人力投入,计算潮差比时考虑了系统误差的影响,计算短期验潮站时考虑了观测误差对深度基准面传递的影响。     

基于PS-InSAR技术的深圳北站表面位移监测研究

利用2015-01-2018-08的40景COSMO-SKyMed HIMAGE雷达影像,采用永久散射体合成孔径雷达干涉测量(permanent scatterers interferometric synthetic aperture radar,PS-InSAR)技术获得了深圳北站时序形变信息,并基于GIS空间分析...     

利用浮标资料初步评估NCEP再分析湍通量

通过与浮标观测资料的对比分析,指出NCEP动量通量、再计算NCEP热通量更能够代表NCEP再分析数据库的数值模拟效果。当风速大于20m/s时,数值模拟的湍通量低于浮标块体湍通量,当风速在10～20m/s时,数值模拟的湍通量高于浮标块体湍通量。同时还发现数值模拟结果的延迟现象,以及不能反映大风过后快速的海气温差变化而引起的感热通量变化。     

Urban three-dimensional expansion and its driving forces —A case study of Shanghai, China

Urban expansion is a phenomenon of urban space increase, and an important measuring index of the process of urbanization. Taking Shanghai as an example, the changes of urban average height and built-up area were studied to represent city’s vertical and horizontal increases respectively, and statistical methods were used to analyze the driving forces of urban expansion. The research drew following conclusions: 1) The urban expansion process of Shanghai from 1985 to 2006 had a clear periodic feature, and could be divided into three stages: vertical expansion in dominance, coordinated vertical and horizontal expansion, and horizontal expansion in dominance. 2) The average height and quantity of buildings in core city were significantly bigger than those in suburbs, but the changing speed of the latter was faster. And 3) urbanization process was the major driving force for the city’s horizontal expansion, while industrial structure improvement was the key driving factor for the vertical expansion. Those two driving forces were simultaneously affected by city’s political factors.     

Experimenta l study on ultrasonic propagation in water-based bentonite slurry

Drilling fluid is a common flushingmedium used in pile foundation, geological drilling and petroleum drilling. Study on ultrasonic propagation properties in drilling fluid is of vital importance, not only for developing equipments to non-contact measuring concrete casting level for bored pile, but also for developing equipments considering drilling fluid as signal channel. The existence of clay particlesmakes the ultrasonic propagation and attenuation in drilling fluid much different from pure water. In order to know the relation among ultrasound frequency, slurry density and depth, a series of laboratory experiments about ultrasound propagation in water-based bentonite slurry were finished. Wavelet method was adopted to process the gained original waves of ultrasonic propagation in slurry, so we knew the velocity and attenuation coefficient of ultrasound propagated in different drilling fluids with different density. The first group experiments shows that with density of drilling fluid increase, ultrasonic velocity will decrease but attenuation coefficient will increase if ultrasonic frequency keep constant. The second group experiments shows that the power of ultrasound will intensify in small bore hole, the attenuation coefficient ismuch smaller than theoretical value.     

长江口外海域三维水动力模拟结果及与观测的比较

Base on ECOMSED model, a theree-dimensional hydrodynamic model is developed in the offshore area near the Changjing Estuary in the East China Sea. This model in driven by tide and wind,as well as inflow and outflowcurrents such as Kuroshio,Changjing runoff. The horizontal resolution is 1/20_°. There have 11 layers on the verticaldirection. The numerical results of 4 main constituents of tide(M²,S²,K¹,O¹)and currents are in good agreement with observation data. Compared with 20 gauge stations,the mean absolute erroe between the caluclated M² tidal amplitude and the observed oned is only 6.72cm; the mean absolute error of phased-lag is 5.23_°.For S²,the mean absolute errors of amplitude and phased-lag are 3.67cm and 7.21_°,respectively. The mean absolute errors of amplitude and phased-lag for K¹ are 3.25cm and 6.63_° For O¹,the mean absolute error of calculation and observation is relatively small, amwith observation data measured during Aug., 2006 in the East China Sea.The correlation coeffiients of current between simulation and observation are greater than 0.75 generally. The three-dimensional hydrodynamic model develiped by this paper can well describe the characters of elevation and current in the offshore near the Changjiang Estuary and can be used as hydrodynamic background to simulate the suspend sediment transport in this sea area.     

RTK技术在南阳市全国土地二次调查中的应用

实时动态（Real Time Kinematic）测量技术,简称RTK技术已风靡全球,它具有全球、全天候工作、定位精度高等优点,在当今测绘界已经得到广泛应用。RTK技术在南阳市全国土地二次调查中起到了关键的作用,大大提高了工程进度,降低了成本。