共查询到20条相似文献,搜索用时 15 毫秒
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Leilei Kou Xiaoqing Wang Maosheng Xiang 《Journal of the Indian Society of Remote Sensing》2014,42(1):1-12
Circular SAR imaging on the geosynchronous orbit is an innovative SAR imaging mode, which can perform high resolution three-dimensional (3D) imaging with continuous observations for a large area. However, for geosynchronous satellites the orbit is severely disturbed by perturbing effects, and the orbit error will be an important factor influencing the SAR imaging on the geosynchronous orbit. In this paper, the effects of the orbit error on performances of 3D geosynchronous circular SAR (GEOCSAR) imaging are analyzed. The error model is firstly made, and then the orbit error propagating into the distance from the radar to the target (range) is derived. Furthermore, the effects of different components of the range error on the quality of focused SAR signals are deduced, based on the 3D GEOCSAR signal model with time-domain correlation algorithm. The analyses and simulations will quantify and verify the required accuracies of GEOCSAR orbit estimation for ensuring the 3D imaging quality. 相似文献
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PRISMS (Portable Remote Imaging System for Multispectral Scanning) is designed for in situ, simultaneous high resolution spectral and 3D topographic imaging of wall paintings and other large surfaces. In particular, it can image at transverse resolutions of tens of microns remotely from distances of tens of metres, making high resolution imaging possible from a fixed position on the ground for areas at heights that is difficult to access. The spectral imaging system is fully automated giving 3D topographic mapping at millimetre accuracy as a by-product of the image focusing process. PRISMS is the first imaging device capable of both 3D mapping and spectral imaging simultaneously without additional distance measuring devices. Examples from applications of PRISMS to wall paintings at a UNESCO site in the Gobi desert are presented to demonstrate the potential of the instrument for large scale 3D spectral imaging, revealing faded writing and material identification. 相似文献
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本文是机器视觉参量下的三维数字摄影测量智能构像基础工作之一:成像系统位置姿态自动跟踪与精密修正,属于摄影测量与机器视觉、数字图像处理等学科交叉的摄像测量领域。针对基于目标3D模型的位姿跟踪问题开展研究,对相关研究的现状进行梳理,并提出系列位姿跟踪与模型修正方法。在完全已知目标3D精确模型的情况下,对于包含丰富直线特征的特殊目标,提出基于直线模型的目标位姿跟踪方法,实现了目标位姿参数的精确跟踪;为处理更为一般目标,利用目标的3D边缘模型,提出法向距离迭代加权最小二乘位姿估计方法及距离图迭代最小二乘位姿跟踪方法。当目标3D直线模型参数不准确时,结合光束法平差思想,提出一种针对序列图像的基于3D直线模型同时位姿跟踪与模型修正方法,联合优化求解目标位姿参数及3D直线模型参数,在模拟空间卫星目标位姿测量的仿真试验中,模型直线朝向、位置误差及目标位姿平均角度、平均位置误差分别为0.3°、3.5 mm及0.12°、20.1 mm。针对包含丰富直线特征的目标,在其3D直线模型完全未知的情况下,提出基于序列图像直线对应的目标结构重建与位姿跟踪方法,利用序列图像信息,在SFM框架下同时优化求解目标直线模型参数及位姿参数,仿真试验条件下,重建模型直线朝向、位置误差及位姿参数平均角度、平均位置误差分别约为0.4°、7.5 mm及0.16°、23.5 mm。 相似文献
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针对监控视频动态目标的空间定位问题,本文在考虑相机畸变的前提下,对监控相机、目标像素坐标和地理场景之间的映射关系进行了研究,提出了基于数字表面模型(DSM)和基于平面约束的目标定位算法。首先,完成相机的标定,确定相机的成像模型;然后,提取畸变校正后的目标像素坐标,并通过目标定位算法计算目标的三维地理坐标;最后,进行了定位精度评定,并分析了两种定位算法的应用特点。本文的定位算法将以像素坐标定位的目标数据解析为以三维坐标定位的空间地理信息,为多摄像头的目标跟踪提供了统一的地理参考框架。 相似文献
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Current research on underwater 3D imaging methods is mainly addressing long range applications like seafloor mapping or surveys of archeological sites and shipwrecks. Recently, there is an increasing need for more accessible and precise close-range 3D acquisition technologies in some application fields like, for example, monitoring the growth of coral reefs or reconstructing underwater archaeological pieces that in most cases cannot be recovered from the seabed. This paper presents the first results of a research project that aims to investigate the possibility of using active optical techniques for the whole-field 3D reconstructions in an underwater environment. In this work we have tested an optical technique, frequently used for in air acquisition, based on the projection of structured lighting patterns acquired by a stereo vision system. We describe the experimental setup used for the underwater tests, which were conducted in a water tank with different turbidity conditions. The tests have evidenced that the quality of 3D reconstruction is acceptable even with high turbidity values, despite the heavy presence of scattering and absorption effects. 相似文献
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Dynamic geospatial complex systems are inherently four‐dimensional (4D) processes and there is a need for spatio‐temporal models that are capable of realistic representation for improved understanding and analysis. Such systems include changes of geological structures, dune formation, landslides, pollutant propagation, forest fires, and urban densification. However, these phenomena are frequently analyzed and represented with modeling approaches that consider only two spatial dimensions and time. Consequently, the main objectives of this study are to design and develop a modeling framework for 4D agent‐based modeling, and to implement the approach to the 4D case study for forest‐fire smoke propagation. The study area is central and southern British Columbia and the western parts of Alberta, Canada for forest fires that occurred in the summer season of 2017. The simulation results produced realistic spatial patterns of the smoke propagation dynamics. 相似文献
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The majority of navigation satellite receivers operate on a single frequency. They compensate for the ionospheric delay using
either an ionospheric model which typically only corrects for 50% of the delay or a thin-shell map of the ionosphere. A 4D
tomographic imaging technique is used to map the free electron density over the full-height of the ionosphere above North
America during autumn 2003. The navigation solutions computed using correction based upon the thin-shell and the full-height
maps are compared in this paper. The maps are used to calculate the excess propagation delay on the L1 frequency experienced
by GPS receivers at selected locations across North America. The excess delay is applied to correct the single-frequency pseudorange
observations at each location, and the improvements to the resulting positioning are calculated. It is shown that the thin-shell
and full-height maps perform almost as well as a dual-frequency carrier-smoothed benchmark and for most receivers better than
the unfiltered dual-frequency benchmark. The full-height corrections perform well and are considerably better than thin-shell
corrections under extreme storm conditions. 相似文献
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《Geoscience and Remote Sensing Letters, IEEE》2009,6(1):82-86
Many realizations of foliage around a hard target are run to obtain the statistical variations of foliage and target responses. This is accomplished by using a hybrid target-foliage model, developed for the investigation of the scattering behavior of metallic targets embedded inside a forest canopy. This model is based on the coherent scattering theory of wave propagation through the foliage and an iterative physical optics approximation of scattering from the target. The model is capable of accounting for the first-order near-field interactions between the hard target and the foliage. Fully polarimetric simulation results of a foliage-camouflaged metallic target having complex geometry are generated at 2 GHz, and a polarization synthesis optimization method for improving signal-to-clutter ratio is carried out by applying genetic algorithms. 相似文献
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现有的室内三维模型重建中,通常将墙等承担空间分隔作用的室内导航元素看作一个整体,通过对墙的提取来实现房间子空间的分割.然而,一面墙的两个墙面形态上的差异会造成室内三维重建过程中房间细节的损失,并且引起门窗提取的困难.针对这一现象,提出了一种细化空间分隔的思想,通过将一面墙细化为两个墙面,利用区域生长算法获取墙面角点,从... 相似文献
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3D coseismic Displacement of 2010 Darfield, New Zealand earthquake estimated from multi-aperture InSAR and D-InSAR measurements 总被引:2,自引:1,他引:1
Differential interferometric synthetic aperture radar (D-InSAR) measures ground deformation only along the line-of-sight (LOS) of the radar, which limits the capability of D-InSAR in investigating the surface damages and the focus mechanisms of earthquakes. We do a three-dimensional (3D) decomposition of the coseismic displacement of the Darfield, New Zealand earthquake that occurred on 3 September 2010 by exploiting the Multi-Aperture InSAR (MAI) and D-InSAR measurements from both ascending and descending L-band PALSAR data. Due to the dispersive nature of the ionosphere and the slight Doppler shift between the forward- and backward-looking interferograms, the ionospheric effects can be more serious in MAI measurements than in D-InSAR. We propose mitigating the ionospheric effects in the MAI processing with the directional filtering and interpolation procedure that has been applied in Offset-tracking. The rupture revealed by the 3D surface displacement fits closely to the Greendale fault, which is believed to be responsible for the earthquake. The horizontal ground motions, mostly eastwards in the hanging wall and westwards in the footwall, reached up to 2.5 m and are anti-symmetric with respect to the Greendale fault. Up to 2.5 m subsidence occurred in the hanging wall, while uplift is found in the footwall with an extreme case of 1.6 m in the far left of the fault. This makes us conclude that the Greendale fault is a normal and dextral strike-slip. It is seen that the MAI measurements are very helpful in the derivation of 3D coseismic displacement fields as it provides more accurate displacement estimation in the north–south direction. 相似文献
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三维激光扫描技术是近年来兴起的一种测量技术,并且正在飞速地拓展其应用领域。笔者尝试将三维激光扫描仪用于玻璃幕墙的设计和安装,阐述了其工作流程和测量的方法,取得了较好的效果,尤其对于异形结构大范围玻璃幕墙设计及安装,明显具有工作效率高、测量精度高的优点,同时还可以提供三维可视化图形,对于同类工程的设计和施工,具有较好的借鉴意义。 相似文献
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按照国家关于文物信息化的有关要求,以及测绘、地理信息相关规范标准,通过采购硬件设备与基础软硬件,搭建文物信息基础运行环境,同时通过遥感影像数据采购、无人机航摄、数据资料整理等方式建立长城资源综合数据库,构建二三维一体化长城资源"一张图"模式.在此基础上,搭建二三维一体化GIS平台,为长城资源三维地理信息应用系统提供数据管理、处理、应用平台接口.并基于基础GIS开发平台,搭建面向吐鲁番长城资源管理的三维地理信息管理平台和面向社会公众的长城资源信息发布系统,为长城资源管理者与社会公众提供信息化管理与宣传展示平台.本文对吐鲁番境内62处军事设施遗址、13条古道、5处重要城址等开展的三维地理信息管理系统建设,为后期研究、保护、展示、考古资源管理及公众教育奠定了坚实的基础. 相似文献
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H. P. Meinzer M. Thorn M. Vetter P. Hassenpflug M. Hastenteufel I. Wolf 《ISPRS Journal of Photogrammetry and Remote Sensing》2002,56(5-6)
Clinical routine is currently producing a multitude of diagnostic digital images but only a few are used in therapy planning and treatment. Medical imaging is involved in both diagnosis and therapy. Using a computer, existing 2D images can be transformed into interactive 3D volumes and results from different modalities can be merged. Furthermore, it is possible to calculate functional areas that were not visible in the primary images. This paper presents examples of clinical applications that are integrated into clinical routine and are based on medical imaging fundamentals. In liver surgery, the importance of virtual planning is increasing because surgery is still the only possible curative procedure. Visualisation and analysis of heart defects are also gaining in significance due to improved surgery techniques. Finally, an outlook is provided on future developments in medical imaging using navigation to support the surgeon's work. The paper intends to give an impression of the wide range of medical imaging that goes beyond the mere calculation of medical images. 相似文献
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圆形标志已广泛应用于近景摄影测量,但由于影像平面与目标平面不能完全平行,所以圆形标志的数字影像一般为椭圆。如果圆形标志点较大,以至于圆形标志中心与其椭圆构像中心的偏差不可忽略。故本文从摄影测量共线条件方程式出发,采用一种基于最小二乘的椭圆拟合算法,推导出偏差计算公式,本文的真正目的在于分析偏差分布规律及偏差间的关系,尽可能降低偏差的影响。 相似文献