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1.
Estimation of Contamination of ERS-2 and POSEIDON Satellite Radar Altimetry Close to the Coasts of Australia 总被引:4,自引:0,他引:4
It is broadly acknowledged that the precision of satellite-altimeter-measured instantaneous sea surface heights (SSH) is lower in coastal regions than in open oceans, due partly to contamination of the radar return from the coastal sea-surface state and from land topography. This study investigates the behavior of ERS-2 and POSEIDON altimeter waveform data in coastal regions and estimates a boundary around Australia's coasts in which the altimeter range may be poorly estimated by on-satellite tracking software. Over one million 20 Hz ERS-2 (March to April 1999) and POSEIDON (January 1998 to January 1999) radar altimeter waveform data were used over an area extending 350 km offshore Australia. The DS759.2 (5'resolution) ocean depth model and the GSHHS (0.2 km resolution) shoreline model were used together to define the coastal regions. Using the 50% threshold retracking points as the estimates of expected tracking gate, we determined that the sea surface height is contaminated out to maximum distance of between about 8 km and 22 km from the Australian shoreline for ERS-2, depending partly on coastal topography. Using the standard deviation of the mean waveforms as an indication of the general variability of the altimeter returns in the Australian coastal region shows obvious coastal contamination out to about 4 km for both altimeters, and less obvious contamination out to about 8 km for POSEIDON and 10 km for ERS-2. Therefore, ERS-2 and POSEIDON satellite altimeter data should be treated with some caution for distances less than about 22 km from the Australian coast and probably ignored altogether for distances less than 4 km. 相似文献
2.
神舟四号高度计波形数据预处理和信息提取 总被引:1,自引:0,他引:1
神舟四号(SZ-4)高度计在国内首次提供了星载雷达高度计回波波形数据.本文中作者分析了SZ-4高度计回波波形的特点,完成波形数据的预处理,并在此基础上完成初步的信息提取.在数据预处理方面,通过SZ-4高度计水陆边界处波形的特点,提出了波形最大幅度控制的方法,筛选回波波形.在波形归一化处理过程中,发现SZ-4高度计波形中存在双峰现象,并指出第二个峰为异常波形区.在波形信息提取方面,利用波形重新跟踪得到的半功率点计算出SZ-4高度计高度跟踪补偿误差,并根据高度计天线指向角和回波波形下降沿斜率之间的关系,从波形后沿提取天线指向角信息.分析结果表明,SZ-4高度计天线指向比较平稳,而跟踪补偿由于变化较大,在计算海面高度时,应作为一项误差源被考虑到. 相似文献
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抚顺发电厂是一座坑口发电厂,受采煤等多种复杂人为及地质因素的影响,厂区发生一系列的变形和破坏.本文基于观测成果对厂区变形规律进行了分析. 相似文献
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SUN Xiao-jie LI Chao-lin WANG Li-bin REN Ri-chun LI Hai-yan ZHUANG Yi-ming LIU Ying-xin SUN Ke .Daqing Petroleum Institute Daqing Heilongjiang China .Coalfield Geological Geophysical Exploration Company of Jilin Province Changchun China .Coal Field Geology Bureun of Jilin Province Changchun China 《吉林大学学报(地球科学版)》2006,(Z2)
已知勘查区深度范围前提下,最大炮检X和道间距ΔX,不可以太大也不可以太小,施工前能够计算出它的允许值范围。 相似文献
7.
基于车载序列影像的建筑立面纹理的快速重建 总被引:5,自引:0,他引:5
提出了一种基于车载序列影像的建筑立面纹理快速重建的方法。首先进行影像预处理,包括畸变差改正、树木遮挡去除等,然后对影像进行自动纠正,在此基础上,自动选择拼接点对影像进行拼接。实验证明了本文方法的有效性。 相似文献
8.
Effects of laser beam alignment tolerance on lidar accuracy 总被引:2,自引:0,他引:2
One of the major lidar error sources not yet analyzed in the literature is the tolerance of the laser beam alignment with respect to the scanning mirror. In this paper, the problem of quantifying these errors is solved for rotating polygon mirror type lidar systems. An arbitrary deviation of the beam from its design direction–the vector of beam misalignment–can be described by two independent parameters. We choose these as horizontal and vertical components of the misalignment vector in the body frame. Either component affects both, horizontal and vertical lidar accuracy. Horizontal lidar errors appear as scan line distortions—along and across track shifts, rotations and scaling. It is shown that the horizontal component of misalignment results in a scan line first being shifted across the track and then rotated around the vertical at the new center of the scan line. Resulting vertical lidar error, being a linear function of the scan angle, is similar to that produced by a roll bias. The vertical component of the beam misalignment causes scan line scaling and an along track shift. The corresponding vertical error is quadratic with respect to the scan angle. The magnitude of these effects is significant even at tight alignment tolerances and cannot be realistically accounted for in the conventional calibration model, which includes only range, attitude and GPS biases. Therefore, in order to attain better accuracy, this model must be expanded to include the beam misalignment parameters as well. Addition of new parameters into the model raises a question of whether they can be reliably solved for. To give a positive answer to this question, a calibration method must utilize not only ground control information, which is typically very limited, but also the relative accuracy information from the overlapping flight lines. 相似文献
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基于二维直接线性变换的数字相机畸变模型的建立 总被引:10,自引:3,他引:10
提出并论证了基于二维直接线性变换的畸变的校正方法。本方法特别适用于各类固态摄像机(CCD、CID、PSD)的畸变模型的建立,以补偿各类像点系统误差。 相似文献