共查询到20条相似文献，搜索用时 640 毫秒
1.
An algorithm (differential mode) is presented for the improvement of harmonic tidal analysis along T/P tracks, in which the differences between the observed sea surface heights at adjacent points are taken as observations. Also, the observation equations are constrained with the results of the crossover analysis; the parameter estimations are performed at 0.1° latitude intervals by the least squares. Cycle 10 to 330 T/P altimeter data covering the China Sea and the Northwest Pacific Ocean (2°-50°N,105°-150°E) are adopted for a refined along-track harmonic tidal analysis, and harmonic constants of 12 constituents in 8 474 points are obtained, which indicates that the algorithm can efficiently remove non-tidal effects in the altimeter observations, and improve the precision of tide parameters. Moreover, parameters along altimetry tracks represent a smoother distribution than those obtained by traditional algorithms. The root mean squares of the fitting errors between the tidal height model and the observations reduce from 11 cm to 1.3 cm. 相似文献
2.
A novel filtering algorithm for Lidar point clouds is presented, which can work well for complex cityscapes. Its main features are filtering based on raw Lidar point clouds without previous triangulation or rasterization. 3D topological relations among points are used to search edge points at the top of discontinuities, which are key information to recognize the bare earth points and building points. Experiment results show that the proposed algorithm can preserve discontinuous features in the bare earth and has no impact of size and shape of buildings. 相似文献
3.
YIN Hui 《地球空间信息科学学报》2000,3(3):69-72
The methods of deformation analysis and modeling at single point are realized easily now,but available approaches do not make full use of the information from monitoring points and can not reveal integrated deformation regularity of a deformable body.This paper presents a fuzzy clusetering method to analyze the correlative relations of multiple points in space,and then the spatial model for a practical dangerous rockmass in the area of Three Gorges,Yangtze River is established,in which the correlation of six points in space is analyzed by geological investigation and fuzzy set theory. 相似文献
4.
WANG Yanbing WU Lixin SHI Wenzhong 《地球空间信息科学学报》2007,10(3):208-212
Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point (IDRVP), to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases. 相似文献
5.
An iterative algorithm to calculate mutual correlation using hierarchical key points and the search space mark principle is proposed. An effective algorithm is designed to improve the matching speed. By hierarchical key point algorithm and mutual correlation coefficients of the matching images, the important points can be iteratively calculated in the images hierarchically, and the correlation coefficient can be obtained with satisfactory precision. Massive spots in the parameter space which are impossible to match can be removed by the search space mark principle. Two approximate continuities in the correlation image matching process, the image gray level distribution continuity and the correlation coefficient value in the parameter space continuity, are considered in the method. The experiments show that the new algorithm can greatly enhance matching speed and achieve accurate matching results. 相似文献
6.
Yonghong Yang 《地球空间信息科学学报》2011,14(1):68-72
In this paper,a special geometry case of spaceborne-airborne bistatic SAR(SA-BiSAR) is considered,in which satellite and aircraft flight paths are parallel and their antennas are steering at the strip map.This case is a simple but typical application example,which is applicable for non-cooperative illumination.The integration time of SA-BiSAR system is derived via the motion of transmitter and receiver footprint.In parallel and stripmap mode,Doppler frequency is obtained through the combination be-tween spaceborne and airborne SAR.Other Doppler properties have been envisaged,including Doppler bandwidth and azimuth resolution.The overall simulation experiments are conducted and some characteristics are exhibited.The critical parameters,which have the significant effect on the SA-BiSAR Doppler properties,are extracted by analytical expressions and numerical simulations.In parallel and strip map mode and with reference to ENVISAT-1,SA-BiSAR system possesses the potential of yielding 10 m azi-muth resolution and 0.5 s integration time for C-band via the analysis of simulation results. 相似文献
7.
Algorithm for generating dem based on cone 总被引：1，自引：0，他引：1
JIANG Hongfei 《地球空间信息科学学报》2000,3(3):30-33
Digital elevation model (DEM) has a variety of applications in GIS and CAD.It is the basic model for generating three-dimensional terrain feature.Generally speaking,there are two methods for building DEM.One is based upon the digital terrain model of discrete points,and is characterized by fast speed and low precision.The other is based upon triangular digital terrain model,and slow speed and high precision are the features of the method.Combining the advantages of the two methods,an algorithm for generating DEM with discrete points is presented in this paper.When interpolating elevation,this method can create a triangle which includes interpolating point and the elevation of the interpolating point can be obtained from the triangle.The method has the advantage of fast speed,high precision and less memory. 相似文献
8.
FriedrichAckermann 《地球空间信息科学学报》1998,(1)
A geo-reference is a global or regional geographical or geodetic coor-dinate system to which sensors or spatial object data are related.Hence,geo-ref-erencing is close to the well known photogrammetric concept of exterior or abso-lute orientation,the common execution of which is indirect,via the use of groundcontrol point.GPS and INS technologies have changed the situation,permittingdirect measurement of position and attitude parameters and making exterior orien-tation feasible without ground control at all,in principle.The analysis of accuracyand reliability performance discloses,however,that especially INS does not yetmeet the high demands of photogrammetry.Moreover,control of systematic er-rors,the problem of datum transformation,and reliability conditions make theuse of some ground control points still mandatory,at least for any high perfor-mance geo-referencing. 相似文献
9.
HUANGPeizhi Poh－ChinLai 《地球空间信息科学学报》2002,5(2):68-73
The geometric and physical analysis methods are conventional methods for the derivation of skeleton lines in the fields of cartography,digital photogrammetry,and related areas.this paper proposes a stepwise approach that uses the physical analysis method in the first stage and the geometric analysis method in the subsequent stage.The physical analysis method analyses the terrain globally to obtain a rough set of skeleton lines for a terrain surface.The rough skeleton lines help to structure the ordering of feature points by the geometric analysis method. 相似文献
10.
基于经验模态分解的高分辨率影像融合(英文) 总被引：3，自引：0，他引：3
High resolution image fusion is a significant focus in the field of image processing. A new image fusion model is presented based on the characteristic level of empirical mode decomposition （EMD）. The intensity hue saturation （IHS） transform of the multi-spectral image first gives the intensity image. Thereafter, the 2D EMD in terms of row-column extension of the 1D EMD model is used to decompose the detailed scale image and coarse scale image from the high-resolution band image and the intensity image. Finally, a fused intensity image is obtained by reconstruction with high frequency of the high-resolution image and low frequency of the intensity image and IHS inverse transform result in the fused image. After presenting the EMD principle, a multi-scale decomposition and reconstruction algorithm of 2D EMD is defined and a fusion technique scheme is advanced based on EMD. Panchromatic band and multi-spectral band 3,2,1 of Quickbird are used to assess the quality of the fusion algorithm. After selecting the appropriate intrinsic mode function （IMF） for the merger on the basis of EMD analysis on specific row （column） pixel gray value series, the fusion scheme gives a fused image, which is compared with generally used fusion algorithms （wavelet, IHS, Brovey）. The objectives of image fusion include enhancing the visibility of the image and improving the spatial resolution and the spectral information of the original images. To assess quality of an image after fusion, information entropy and standard deviation are applied to assess spatial details of the fused images and correlation coefficient, bias index and warping degree for measuring distortion between the original image and fused image in terms of spectral information. For the proposed fusion algorithm, better results are obtained when EMD algorithm is used to perform the fusion experience. 相似文献
11.
以相邻点海面高度差为观测量的沿迹调和分析新方法 总被引：2，自引：0，他引：2
采用TOPEX/POSEIDON卫星轨迹上相邻点的海面高差作为观测量,在交叉点分析结果的控制下构成同一弧段上观测量在两相邻交叉点间的综合观测方程,以轨迹上纬差0.1°的正常点的潮汐参数构成总体待估参数系列,实施最小二乘综合解算。分析结果表明,这种差分模式可以基本消除非潮汐因素的影响,提高潮汐参数估计的精度和可靠性,可比一般沿迹逐点分析给出更为平滑的沿迹参数分布,更符合海洋潮汐运动的物理背景。 相似文献
12.
On the basis of the characteristic of the perfect spatial distribution of the T/P altimeter data, a spatial harmonic tidal analysis is performed, which transfers tidal harmonic constantsH andg of each constituent into a pair of parameters: the cosine part U and sine partV. And each part is expanded into a polynomial. The polynomial coefficients are estimated with altimeter data upon the least squares criteria. Thus the models of principal tidal waves in the South China Sea are established. 72 cycles of T/P data from cycle 11 through 82 are included in the calculation. The models are evaluated with different approaches and data set. The conclusions are that the tide modes can provide partial tide amplitudes with 3 cm accuracy, and that phase lags deviation of those tides with amplitude large than 10 cm are within ±10°. 相似文献
13.
BAO JingyangCHAO DingboLI Jiancheng 《地球空间信息科学学报》2001,4(4):19-24
1 ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅ 1 96 0’ｓ ,ｅｓｐｅｃｉａｌｌｙｄｕｒｉｎｇｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ,ｍａｎｙｔｉｄａｌｉｓｔｓｈａｖｅｓｔｕｄｉｅｄｏｎｔｈｅｔｉｄａｌｗａｖｅｓｙｓｔｅｍｓｏｆｔｈｅＳｏｕｔｈＣｈｉｎａＳｅａ .ＹｅＡｎｌｅ ,ｅｔａｌ.(1 983 ) ,ＳｈｅｎＹｕｊｉａｎｇ ,ｅｔａｌ.(1 985 ) ,ＦａｎｇＧｕｏｈｏｎｇ,ｅｔａｌ.(1 994) ,ａｎｄＣａｏＤｅｍｉｎｇ ,ｅｔａｌ.(1 997)ｓｉｍｕｌａｔｅｄｔｈｅｔｉｄａｌｆｉｅｌｄｉｎｔｈｉｓａｒｅａｂａｓｅｄｏｎｔｈｅｎｕｍｅｒｉ… 相似文献
14.
联合TOPEX/Poseidon与Geosat/ERM测高资料建立区域潮汐模型的研究 总被引：2，自引：1，他引：2
利用近十年的T/P测高数据来反演南海(8°~23°N,109°~120°E)九个主要分潮的潮汐参数,并计算了Geosat/ERM卫星对应的各主分潮的混叠周期及Rayleigh周期。根据潮汐参数提取的要求,选取了7个主分潮,为了克服混叠影响,将T/P沿迹点处的主要分潮间的5组差比关系引入到Geosat沿迹点处,并利用T/P提供的Sa模型去除Sa对M2的扰动影响。精度估计的结果表明,Geosat/ERM反演的潮汐参数的精度与传统的月分析结果的精度相近;因差比关系的捆绑,整个全日和半日潮族迟角偏差相近,这主要和Geosat/ERM的轨道设计有关。本文的方法可以应用于利用轨道调整后的T/P卫星的测高数据提取潮汐参数。 相似文献
15.
选取4种不同潮汐类型的验潮站实测潮位资料,对验潮零点在一定范围内变动对调和分析结果的影响进行分析,结果表明,一年的潮位数据中若后续6个月的数据发生10 cm、20 cm、30 cm零点漂移,各分潮振幅最大变化量为0.47 cm,迟角为0.16°。采用1~12个月不同中期尺度的实测数据,对调和结果的精度进行分析,结果表明,当潮位观测数据时间尺度小于6个月时,其4个主要分潮O_1、K_1、M_2、S_2振幅综合中误差在2 cm以上,迟角中误差在2°以上,具有显著的不稳定性;相同时间尺度的不同潮汐类型的潮位站潮位资料调和分析得到的主要分潮的振幅精度差异较大,迟角分布相似。当潮位观测数据时间尺度达到或多于6个月时,澳门站、汕尾站的分潮综合中误差分别为1.16 cm、0.61 cm,厦门站、北海站分别为2.90 cm和2.51 cm;各分潮迟角中误差均在2°内。当时间尺度超过9个月后,4个验潮站分潮振幅综合中误差均在2 cm以内,各分潮迟角中误差均在1°左右。 相似文献
16.
LUO Jia LI Jiancheng CHAO Dingbo 《地球空间信息科学学报》2003,6(1):19-23
1 ＩｎｔｒｏｄｕｃｔｉｏｎＴｏｄｅｖｅｌｏｐｔｈｅｏｃｅａｎｗｉｄｅｌｙａｎｄｄｅｅｐｌｙ ,ｗｅｎｅｅｄａｂｕｎｄａｎｔｏｃｅａｎｉｎｆｏｒｍａｔｉｏｎ .Ａｓａｎｅｓｓｅｎｔｉａｌｐａｒｔｏｆｓｕｃｈｉｎｆｏｒｍａｔｉｏｎ ,ｓｅａｆｌｏｏｒｔｏｐｏｇｒａｐｈｙｐｌａｙｓａｖｅｒｙｉｍｐｏｒｔａｎｔｒｏｌｅｉｎａｖａｒｉｅｔｙｏｆｍａｒｉｎｅａｃｔｉｖｉｔｉｅｓ .Ｈｏｗｅｖｅｒ,ｔｈｅｈｉｇｈｃｏｓｔｆｏｒｏｃｅａｎｂａｔｈｙｍｅｔｒｉｃｓｕｒｖｅｙｉｎｇｌｉｍｉｔｓｔｈｅａｐｐｌｉｃａｔｉｏｎｏ… 相似文献
17.
中国沿岸主要验潮站海图深度基准面的计算与分析 总被引：9，自引：0，他引：9
对中国沿岸有代表性的15个验潮站的多年潮位观测资料，以年序列进行调和分析并据调和常数计算验潮站的海图深度基准面，分析了由年观测序列求得的调和常数和海图深度基准面的稳定性，研究和更新了理论上可能最低潮面计算中的浅水分潮和长周期分潮订正算法。计算结果表明，中国沿岸不同验潮站的海图深度基准面定义和算法存在差异，新的订正算法计算的可能最低潮面和最低天文潮面具有意义一致性，研究成果能够用来精化和重新构建中国沿岸海图深度基准面。 相似文献
18.
Aliasing of the diurnal and semi-diurnal tides is a major problem when estimating the ocean tides from satellite altimetry.
As a result of aliasing, the tides become correlated and many years of altimeter observations may be needed to seperate them.
For the three major satellite altimetry missions to date i.e., GEOSAT, ERS-1, and TOPEX/POSEIDON (T/P), the alias periods
as well as the Rayleigh periods over which the tides decorrelate can be identified. Especially in case of GEOSAT and ERS-1,
severe correlation problems arise. However, it is shown by means of covariance analyses that the tidal phase advance differences
on crossing satellite groundtracks can significantly reduce the correlations among the diurnal and semi-diurnal tides and
among these tides and the seasonal cycles of ocean variability. Therefore, it has been attempted to solve a multi-satellite
response tidal solution for the diurnal and semi-diurnal bands from a total of 7 years of altimetry. Unfortunately, it could
be shown that the GEOSAT and ERS-1 orbit errors are too large to improve a 3-year T/P tidal solution with about 2 years of
GEOSAT and 2 years of ERS-1 altimeter observations. However, these results are preliminary and it is expected that more accurate
orbits, which have become available recently for ERS-1, and additional altimeter data from ERS-2 and the GEOSAT Follow-On
(GFO) should lead to an improved T/P tidal model.
Received: 4 May 1999 / Accepted: 24 January 2000 相似文献
19.
P. Moore 《Journal of Geodesy》1987,61(3):223-234
Starlette was launched in 1975 in order to study temporal variations in the Earth’s gravity field; in particular, tidal and
Earth rotation effects. For the period April 1983 to April 1984 over12,700 normal points of laser ranging data to Starlette have been sub-divided into49 near consecutive 5–6 day arcs. Normal equations for each arc as obtained from a least-squares data reduction procedure, were
solved for ocean tidal parameters along with other geodetic and geodynamic parameters. The tidal parameters are defined relative
to Wahr’s body tides and Wahr’s nutation model and show fair agreement with other satellite derived results and those obtained
from spherical harmonic decomposition of global ocean tidal models. 相似文献
20.
A. J. E. Smith B. A. C. Ambrosius K. F. Wakker P. L. Woodworth J. M. Vassie 《Journal of Geodesy》1997,71(11):695-703
Three years of TOPEX/POSEIDON altimeter data have been processed at Delft Institute for Earth-Oriented Space Research (DEOS)
to solve the major diurnal and semi-diurnal constituents of the global ocean tide using the two classical methods of tidal
analysis, i.e. the harmonic and response analyses. Some experiments with the parameters in the response formalism show that the tidal admittance
in both the diurnal and semi-diurnal band can be adequately described with a lag interval of 2 days and a number of lags of
three. Results of both methods are evaluated from the differences with the most recent Grenoble hydrodynamic model (FES95.2)
and from the fit with the harmonic constants of a globally distributed set of tide gauges. It was found that the solutions
of the two methods differ at the millimeter level and are thus fully equivalent, which is confirmed by the tide gauges and
the differences with FES95.2. From the comparisons with the Grenoble model it was found that the M
2 and S
2 solutions of that model likely contain bathymetric errors which are of the order of 1–2 cm for M
2 and 0.5 cm for S
2.
Received: 18 December 1996 / Accepted: 12 May 1997 相似文献