Shape analysis and multispectral classification in geological remote sensing     

Andrea G. Fabbri  Freek D. van der Meer  Carlos R. Valenzuela  Cornelius A. Kushigbor 《Mathematical Geology》1993,25(7):773-793

This paper discusses the usage of mathematical morphology in image processing of remotely-sensed data for geologic interpretation. Particular attention is given to noise-reducing transformations of spectral bands before and after different methods of classification, and to the usage of textural context. The development of a viable processing strategy requires a multidisciplinary approach and expert knowledge in different areas: (a) geology, geomorphology, and vegetation in a study area, (b) properties of the sensor for imagery photointerpretation, (c) spectral/spatial properties of the digital data within an integrated dataset (remote sensing and ancillary data), and (d) data-processing tools including mathematical morphology theory. Examples of geometric characterization of Canadian LANDSAT scenes are described in which shape measurements are obtained using a PC-based hybrid image-processing and geographic information system, termed ILWIS, which was developed at ITC, in the Netherlands. Classes from supervised and unsupervised classification are compared to guide in geological mapping. Classes over individual occurrences of broad vegetation-landform units are studied to aid in environmental mapping. Field knowledge is the context necessary to construct expert procedures to drive sequences of data-processing steps toward a target result such as optimal classification, enhancement, or feature extraction. The interaction between expert rules and the image-processing steps can be based on synthetic measurements of shape to quantize the information either spatially or spectrally. Many useful geometrical transformations of spatially-distributed data are extensions or generalizations of spatial analysis functions typical of geographic information systems.  相似文献   

太阳辐射和电池电压对Eppley大气辐射表测值的影响     

周允华  项月琴 《高原气象》1993,12(1):102-110

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用数字测高仪漂移测量研究电离层声重波扰动   总被引：8，自引：1，他引：8  

万卫星  张兆明 《地球物理学报》1993,36(5):561-569

数字测高仪Digisonde中的漂移测量,常用来研究小尺度电离层扰动,如电离层小不均匀体的漂移。文中提出一种新的分析方法,利用漂移测量数据中多普勒频移和到达角参量的最大熵动态功率谱,估算声重波一类大尺度电离层扰动的水平传播速度和传播方向。作为实例,研究了Millstone Hill测高仪站的漂移观测资料,并对处理结果进行了初步分析。分析结果表明,从数字测高仪漂移测量数据中,可有效地提取声重波一类大尺度电离层扰动的传播参量,在电离层动力过程的研究中很有意义。  相似文献   

Observations of geomagnetic pulsations and variations with a new borehole magnetometer down to depths of 3000 m   总被引：1，自引：0，他引：1  

K. Spitzer 《Geophysical Journal International》1993,115(3):839-848

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A triaxial magnetometer has been developed for investigating the in situ skin effect of horizontal geomagnetic pulsations and variations in deep boreholes. The observations were carried out in the pilot borehole of the Continental Deep Drilling Program of Germany (KTB) down to depths of 3000 m and up to temperature of 90 C. A weak skin effect, due to the known very low conductivity of the penetrated crystalline rocks, of 90 to 95 per cent in amplitude and -5 to -10 rotation in phase has been observed at periods of 10 s and magnetometer depth of 2400 m.
An essential prerequisite for all calculations is the accurate determination of the orientation of the downhole magnetometer. It is demonstrated how oriented record samples of temporal variations at depth correlate precisely with those from the surface.
Results from surface magnetotelluric (MT) investigations show strong local distortions of the telluric field. The distortion of the MT tensor response has been determined by means of newly introduced skin-effect transfer functions, which are assumed to be undistorted.  相似文献   

不等周期断层形变测量环境因子影响的研究     

刘文义  李建新等 《华南地震》1991,11(1):65-69

本文在研究和分析环境因子对断层测量年周变和季节性变化影响的基础上，归纳出断层形变测量年周变的变化规律，并针对不等周期观测资料，建立了形变测量的准线性动态数学模型，最后，对门源地震有异常的扁都口资料用上述模型进行了处理，结果是比较满意的。  相似文献   

Fast-changing processes in a medium subject to loading as detected by resistivity measurements     

Wojciech Stopiński  Gienadiy A. Sobolev  Aleksandr W. Ponomaryov  Vladimir Los 《Pure and Applied Geophysics》1991,136(1):49-58

Making measurements of electric resistivity at 16 s intervals, the authors noticed fast changes of this parameter prior to the occurrence of the main fracture. The changes are superposed on bay pulsations of increasing amplitude and decreasing period. This finding opens prospects for a wider use of an electric resistivity method and proves the high quality of automatic instruments, in particular their high resolution. It also gives evidence for the occurrence of short-period precursors in the fracture zone while the main fracture is being formed.  相似文献   

钻孔伽玛场理论及形态系数计算的进一步研究     

段波 《铀矿地质》1991,7(1):49-58

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苏北平原井下摆观测效果的讨论     

徐元耀 《地震地磁观测与研究》1994,15(6):31-35

文章以江苏省大丰台、盐城台、淮阴台、海安台，射阳台井下摆观测为例。比较它们的观测结果，分析认为井下摆的观测效果不仅与地面复盖层的厚度有关，而且与井下摆周围的环境干扰，观测用井的质量有关。为了提高井下摆观测效果，应尽量减少环境干扰，并注意井的垂直度和固井，文章还指出，沿海地区井下摆受海浪干扰相当显著的。  相似文献   

磁纬20°以下地区哨声多台宽带定向观测及其初步结果   总被引：1，自引：0，他引：1  

徐继生  田茂 《地球物理学报》1989,32(2):125-134

武汉大学哨声组与日本名古屋大学空电研究所合作于1988年1月在我国南方进行了哨声多台宽带定向测量。利用近两年研制的宽带数字化频率追踪定向分析系统,首次获得了磁纬20°以下地区哨声波出口区与偏振状态的实验结果。初步分析发现,在湛江附近（磁纬约10°N）存在一个比较稳定的哨声路径出口区,三台同时接收到的哨声大多从这同一出口区透射出来;有时存在两个出口区,一个仍位于湛江附近,另一个位于桂林和武昌之间;沿两条不同路径传播的同源哨声具有几乎相同的色散。本文所做的非导管射线追踪计算能比较满意地解释定向实验结果。另外,此次观测中还发现一些新的有意义的现象,如记录到近百例两跳、三跳及五跳回波等,这在低纬地区是非常少见的。  相似文献   

NOAA WP-3D instrumentation and flight operations on AGASP-II     

R. C. Schnell  T. B. Watson  B. A. Bodhaine 《Journal of Atmospheric Chemistry》1989,9(1-3):3-16

The second Arctic Gas and Aerosol Sampling Program (AGASP-II) was conducted across the non-Soviet Arctic in March and April 1986, to study the aerosol, gaseous, chemical, and optical properties of Arctic haze. One component of the program was supported with an instrumented NOAA WP-3D atmospheric research aircraft. Measurements of wind, temperature, ozone, water vapor, condensation nucleus concentration, and aerosol scattering extinction coefficient were used to determine the locations and properties of haze layers. The first three NOAA WP-3D research flights were conducted north of Barrow, Alaska, and over the Beaufort Sea northeast of Barter Island, Alaska. The next three sampled conditions in the high Arctic near Alert, Northwest Territories, Canada. All basic meteorological, gas, and aerosol systems are described. The WP-3D flight tracks and operations are presented.  相似文献