SAR和光学异源遥感图像匹配方法的探讨     

张翰墨  尤红建 《测绘科学》2012,37(6):118-121,129

本文针对SAR和光学遥感图像的异源遥感图像匹配的问题,采用6种基于图像灰度信息的相似性度量方法进行研究和实验。在求得图像间旋转和尺度参数的基础上,重点比较了如何提取平移量。采用了包括归一化互相关、相似率、结构相似性、交互方差、互信息和f散度的方法,并根据SAR图像特性进行了部分改进,得到了不同场景下的实验结果,最后对结果进行了比较和分析。结果表明针对不同场景中匹配方法各有优势,其中归一化互相关方法和f散度方法在场景适应性及精度上表现出了很好的适应性。  相似文献   

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest     

D. Cava  G. G. Katul  A. M. Sempreviva  U. Giostra  A. Scrimieri 《Boundary-Layer Meteorology》2008,128(1):33-57

Within the canopy sub-layer (CSL), variability in scalar sources and sinks are known to affect flux–variance (FV) similarity relationships for water vapour (q) and carbon dioxide (C) concentrations, yet large-scale processes may continue to play a significant role. High frequency time series data for temperature (T), q and C, collected within the CSL of an uneven-aged mixed coniferous forest in Lavarone, Italy, are used to investigate these processes within the context of FV similarity. This dataset suggests that MOST scaling describes the FV similarity function of T even though the observations are collected in the CSL, consistent with other studies. However, the measured FV similarity functions for q and C appear to have higher values than their temperature counterpart. Two hypotheses are proposed to explain the measured anomalous behaviour in the FV similarity functions for q and C when referenced to T. Respired CO₂ from the forest floor leads to large positive excursions in the C time series at the canopy top thereby contributing significantly to both C variance increase and C vertical flux decrease—both leading to an anomalous increase in the FV similarity function. For q, transport of dry air from the outer-layer significantly increases both the variance and the water vapour flux. However, the expected flux increase is much smaller than the variance increase so that the net effect remains an increase in the measured FV similarity function for water vapour above its T counterpart. The hypothesis here is that identifying these events in the temporal and/or in the frequency domain and filtering them from the C and q time series partially recovers a scalar flow field that appears to follow FV similarity theory scaling. Methods for identifying both types of events in the time and frequency domains and their subsequent effects on the FV similarity functions and corollary flow variables, such as the relative transport efficiencies, are also explored.  相似文献   

南京冬季城、郊近地面湍流特征的对比分析   总被引：1，自引：0，他引：1  

彭江良  吴息  江志红  刘红年 《南京气象学院学报》2008,31(6):871-878

利用2006年2月17日—3月2日南京及其郊区的近地层湍流资料,分析了城、郊下垫面的无量纲化风速、温度的湍流特征,验证了Monin-obukhov（M-O）相似理论在城、郊下垫面的适用性,并与其他城市和地区的观测结果进行了比较,结果表明：在市区和郊区无量纲脉动风速标准差随稳定度的变化虽然都符合“1/3”次方律,但城、郊有一定差异,尤其在水平方向更为明显。在非中性时垂直向的变化要比水平向更符合“1/3”次方律;σT/｜T＊｜与Z/L关系在城、郊有一定差异,在不稳定时在市区和郊区分别按“-1/3”次和“-2/3”次方规律变化,而在稳定时市区按“-2/3”次方变化,郊区无普适函数关系。在稳定和不稳定条件下,城、郊σT/｜T＊｜都随着｜Z/L｜的减小而增大。  相似文献   

青藏高原东坡理塘地区近地层湍流特征研究   总被引：7，自引：3，他引：4       下载免费PDF全文

李英  李跃清  赵兴炳 《高原气象》2009,28(4):745-753

利用中国气象局成都高原气象研究所在青藏高原东坡理塘地区建立的大气综合观测站观测资料, 以2006年1月和7月涡旋相关资料分别代表冬季和夏季, 分析和比较了该地区近地层包括风速、 风向、 大气稳定度在内的平均场特征, 以及湍流强度、 无量纲化风脉动方差相似性和地表通量变化特征,结果表明, 1月和7月稳定度基本集中在±0.5和±0.25之间; 湍流在<2 m·s-1的风速环境中发展最为旺盛, 随着风速的增大湍流强度减小迅速; 无量纲化三维风脉动方差符合Monin-Obukhov相似理论的“1/3”定律, 其最佳通用相似函数在稳定和不稳定条件下都可以拟合得到; 地表通量均表现出明显的日变化特征, 1月以感热为主, 潜热很小; 7月以潜热为主, 感热较小。  相似文献   

Surface-Layer Fluxes in Stable Conditions   总被引：2，自引：2，他引：0  

J. F. Howell  J. Sun 《Boundary-Layer Meteorology》1999,90(3):495-520

Micrometeorological tower data from the Microfronts experiment are analyzed. Scale-dependencies of the flux and flux sampling error are combined to automatically determine Reynolds turbulence cut-off time scales for computing fluxes from time series. The computed downward heat flux at the 3 m height averaged over nine nights with 7.3 hours each night is 20% greater than the downward heat flux computed at the 10 m height. In contrast, there is only a 1.2% difference between 3 m and 10 m heat fluxes averaged over daytime periods, and there is less than a 2% difference between 3 m and 10 m momentum fluxes whether averaged over nighttime or daytime periods.Stability functions, M(z/L) and H(z/L) are extended to z/L up to 10, where z is the observational height and L is the Obukhov length. For 0.01 < z/L < 1 the estimated functions generally agree with Businger-Dyer formulations, though the H estimates include more scatter compared to the M estimates. For 1 < z/L < 10, the flux intermittency increases, the flux Richardson number exceeds 0.2, and the number of flux samples decreases. Nonetheless the estimates of the stability function M based on 3-m fluxes are closer to the formula proposed by Beljaars and Holtslag in 1991 while the M functions based on 10-m fluxes appears to be closer to the formula proposed by Businger et al. in 1971. The stability function H levels off at z/L = 0.5.  相似文献   

用户GPS轨迹数据支持下的出行安全分析     

张勇  朱大明  冯宇  代德成 《测绘通报》2020,(5):73-79

安全是每次出行的重要因素之一，传统方法大多基于人力或视频协同才能完成安全监控，缺少以轨迹数据度量出行的方法。定位和跟踪系统的技术进步，GPS卫星定位技术的不断发展与普及，使利用车载导航装置、手持GPS装置收集及使用GPS数据点成为可能。本文提出了一种基于用户GPS轨迹数据评价安全的方法，并以校区内宿舍与实验室间的轨迹数据为研究对象，验证了方法的有效性。研究表明：用户轨迹在离开安全轨迹处，获得较低的安全得分。反之，用户轨迹如果与安全轨迹极为相似，则获得很高的安全得分。该方法在检验用户轨迹是否与安全轨迹相似极为高效，同时以轨迹数据的形式反映用户的出行安全。  相似文献   

Turbulence Structure of the Unstable Atmospheric Surface Layer and Transition to the Outer Layer   总被引：4，自引：4，他引：0  

K.G. McNaughton 《Boundary-Layer Meteorology》2004,112(2):199-221

We present a new model of the structure of turbulence in the unstable atmospheric surface layer, and of the structural transition between this and the outer layer. The archetypal element of wall-bounded shear turbulence is the Theodorsen ejection amplifier (TEA) structure, in which an initial ejection of air from near the ground into an ideal laminar and logarithmic flow induces vortical motion about a hairpin-shaped core, which then creates a second ejection that is similar to, but larger than, the first. A series of TEA structures form a TEA cascade. In real turbulent flows TEA structures occur in distorted forms as TEA-like (TEAL) structures. Distortion terminates many TEAL cascades and only the best-formed TEAL structures initiate new cycles. In an extended log layer the resulting shear turbulence is a complex, self-organizing, dissipative system exhibiting self-similar behaviour under inner scaling. Spectral results show that this structure is insensitive to instability. This is contrary to the fundamental hypothesis of Monin--Obukhov similarity theory. All TEAL cascades terminate at the top of the surface layer where they encounter, and are severely distorted by, powerful eddies of similar size from the outer layer. These eddies are products of the breakdown of the large eddies produced by buoyancy in the outer layer. When the outer layer is much deeper than the surface layer the interacting eddies are from the inertial subrange of the outer Richardson cascade. The scale height of the surface layer, z _s, is then found by matching the powers delivered to the creation of emerging TEAL structures to the power passing down the Richardson cascade in the outer layer. It is z _s = u _* ³ /k_s, where u _* is friction velocity, k is the von Kármán constant and _s is the rate of dissipation of turbulence kinetic energy in the outer layer immediately above the surface layer. This height is comparable to the Obukhov length in the fully convective boundary layer. Aircraft and tower observations confirm a strong qualitative change in the structure of the turbulence at about that height. The tallest eddies within the surface layer have height z _s, so z _s is a new basis parameter for similarity models of the surface layer.  相似文献   

基于栅格数据的面状目标空间方向相似性研究     

郭庆胜  丁虹 《武汉大学学报(信息科学版)》2004,29(5):447-450,465

提出了基于栅格数据的面状目标之间的两种空间方向相似性的计算方法：利用栅格数据的特征和方向关系矩阵计算空间方向相似性；基于单个栅格单元与参考目标之间角度的变化计算面状目标之间空间方向相似性。这两种方法简化了由Goyal提出的基于方向关系矩阵模型计算空间方向相似性的方法，克服了方向产生某些细微变化时的限制，在计算面状目标空间方向相似性时具有更广泛的适用性。  相似文献   

Unravelling the microfacies signatures of parasequences using computer-optimized similarity matrices     

Guy H. Spence  Annie Arnaud-Vanneau†  Hubert Arnaud†  Maurice E. Tucker‡ 《Sedimentology》2004,51(6):1243-1271

The microfacies of a Lower Cretaceous carbonate drillcore from Oman are characterized using optimizing matrices of Jaccard's similarity coefficients of community. Other than systems tract boundaries, there is no obvious evidence of individual parasequences in the core. However, diagnostic patterns in microfossil distribution identify environmental gradients recording changes in water depth. These gradients are used to define individual parasequences, parasequence sets, stacking patterns and key surfaces. The patterns suggest that deposition was controlled by successive fourth‐ to fifth‐order (high‐frequency) relative sea‐level cycles superimposed on an underlying third‐order relative sea‐level rise. Although the correlation of these depositional subunits to systematic changes in water depth and the rate of carbonate accumulation alone is not incontrovertible proof of such a sea‐level control, concurrent multiorder relative sea‐level cyclicity provides by far the most likely explanation. A microfacies deposited when the water depth was shallowing is characterized by a relay of microfossils with affinities that shallow upwards. Conversely, a microfacies that records a gradual increase in water depth has a relay of microfossils with affinities that deepen upwards. Microfacies characterized by an assemblage of microfossils with similar affinities record deposition when the benthic environmental conditions remained stable, either because of an equilibrium between shallow water carbonate deposition and rising sea level, or in deeper water where sediment composition was relatively insensitive to changes of water depth. Microfacies characterized by mixed affinity assemblages record syndepositional reworking. During periods of embedded multiorder sea‐level changes, individual parasequences within systems tracts are shown to record more complex environmental gradients than simply the repetition of successive shallowing‐up units as traditionally represented in carbonate sequence stratigraphic models. The microfacies of an individual parasequence may shallow up, or may record both deepening‐up and shallowing‐up depositional phases, as well as periods of sedimentation when benthic environments remained stable. Individual parasequence boundaries may be submarine or subaerial unconformities, or be conformable, as part of a predictable stratigraphic pattern related to the temporal position of an individual parasequence within the underlying third‐order cycle of relative sea‐level change. The hitherto ubiquitous use of assemblages to describe carbonate microfacies, coupled with the widespread use of the metre‐scale shallowing‐up template to identify parasequences, may have led to such complexities previously being overlooked.  相似文献   

大气边界层热量输送的非局地多尺度湍流理论及试验研究   总被引：4，自引：1，他引：4       下载免费PDF全文

朱蓉  徐大海 《应用气象学报》2005,16(3):273-282

该文在大气边界层多尺度湍流理论和湍流穿越理论的基础上，建立了大气边界层感热通量的非局地多尺度湍流计算方法，并选用1998年5～8月份第二次青藏高原大气科学试验（TIPEX）的大气边界层综合观测基地昌都站观测资料，分别用感热通量的非局地多尺度湍流计算方法和经典相似理论计算感热通量。对计算结果的对比分析表明，用感热通量的非局地多尺度湍流计算方法能计算出感热通量的逆梯度输送，也能计算出青藏高原近中性层结条件下明显的感热通量。此外，多尺度湍流理论还有待进一步发展完善，提高感热通量的计算精度。  相似文献