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61.
3D激光扫描应用于开采沉陷相似材料模型观测 总被引:2,自引:1,他引:1
根据开采沉陷相似材料模型实验的特点,采用了三维激光扫描仪对开采沉陷相似材料模型进行观测,得到了测点的拟合与建模两种三维坐标数据,分析了模型的下沉曲线,实现了用三维激光扫描仪对开采沉陷相似材料模型观测新方法的研究. 相似文献
62.
针对地面三维激光扫描技术中多视点云数据配准的问题,提出了一种基于控制测量的点云数据配准新方法。该方法的基本原理是:首先借助人工标志完成水平角度、竖直角度以及斜距测量工作;然后利用闭合导线或者附合导线测量原理,计算闭合差,通过分配闭合差,获取高精度的控制点坐标数据;最后按照定向法原理完成点云数据配准工作。利用地面三维激光扫描仪Riegl PLM321进行辅助法数据配准实验,通过对比公共点配准结果表明:基于控制测量的数据配准方法是可行的,它不仅可以满足建模工作的需要,而且克服了传统串联式配准方法中误差累积的弊端。 相似文献
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S. A. Pisarevsky M. T. D. Wingate M. K. Stevens P. W. Haines 《Australian Journal of Earth Sciences》2013,60(4):561-572
A partial record of the positions of Australia during Middle to Late Neoproterozoic time is provided by palaeomagnetic results for samples from the Lancer 1 stratigraphic drillhole in Western Australia. Lancer 1 was drilled vertically to 1501 m, through essentially horizontal Neoproterozoic strata of the western Officer Basin. We studied 123 samples from 28 intervals of drillcore which were oriented by matching features (fractures, cross-beds, etc.) in the core with oriented acoustic scanner images of the drillhole walls. Three new palaeopoles are reported for red mudstones and sandstones (redbeds) of the Browne (44.5°N, 141.7°E, dp = 5.1°, dm = 9.0°), Hussar (62.2°N, 85.8°E, dp = 7.3°, dm = 14.6°), and Kanpa (74.0°N, 128.8°E, dp = 7.7°, dm = 14.8°) Formations of the ca 830 – 720 Ma Buldya Group (Supersequence 1), which exhibit stable, two-polarity magnetisations carried by fine-grained hematite and magnetite. The overlying ca 610 – 590 Ma Wahlgu Formation glaciogenic diamictite (Supersequence 3) yielded dispersed directions and an imprecise palaeopole that overlaps results from the glaciogenic Elatina Formation and other Late Neoproterozoic rock units. The results help to elaborate the Middle to Late Neoproterozoic apparent polar wander path for Australia and indicate, in agreement with palaeoclimatic data and previous palaeomagnetic studies, that the continent was slow-moving and occupied low latitudes at this time. Assuming that Australia and Laurentia were still joined at ca 780 Ma, comparison of the new Hussar Formation palaeopole with coeval Laurentian data favours AUSMEX, rather than SWEAT or AUSWUS, as the most likely configuration of these two continents in Rodinia. This preliminary study of Lancer 1 demonstrates the utility of acoustic scanner logs for orienting drillcores, as well as the scope for additional sampling and palaeomagnetic studies of Lancer 1, and other oriented drillcores, to yield a more continuous record of Australia's past motions and to provide magnetostratigraphic data for enhancing inter-basin correlations. 相似文献
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Anne‐Lise Montreuil Joanna E. Bullard Jim H. Chandler Jon Millett 《地球表面变化过程与地形》2013,38(15):1851-1868
Embryo dunes are often ephemeral, but can develop to become established coastal foredunes. In 2001 a patch of embryo dunes 13.11 m2 appeared on a beach in north Lincolnshire, UK and had expanded to over 3600 m2 by 2011. The rate of expansion is linked to storm occurrence, where expansion is slowed during years with a higher incidence of storm surges. From July 2009–October 2010 seasonal changes in dune field topography were determined using terrestrial laser scanning (TLS) data. Vegetation is important in the development of embryo dunes, but can cause errors in TLS data. Tests evaluating the impact of vegetation on the TLS data suggest the minimum elevation value from the TLS point cloud within a 0.05 m grid cell gives a good approximation of the ground surface. Digital elevation models (DEMs) of the dunes constructed using filtered data showed the embryo dunes underwent a classic seasonal cycle of erosion during the winter and accretion during the summer. For example from October 2009 to April 2010 over 375 m3 of sediment was eroded from the dunes whereas during spring and summer 2010 the dune field gained over 600 m3 of sand. The overall magnitude of change in dune height and volume from season to season exceeded the errors associated with the construction of the DEM from the TLS data and the vegetation filtering process, which suggests TLS can be useful for documenting topographic change in vegetated dunes. After 10 years, the patch of embryo dunes is still expanding but has not yet merged with more established foredunes to landward. Aeolian process measurements indicate that, at present, the embryo dunes do not prevent sand from reaching the foredunes, however the rate of foredune progradation has slowed concurrently with the expansion of the embryo dune field. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
68.
C. Legout F. Darboux Y. Nédélec A. Hauet M. Esteves B. Renaux H. Denis S. Cordier 《地球表面变化过程与地形》2012,37(9):984-993
Point measurements of flow rate, depth or velocity are not sufficient to validate overland flow models, particularly when the interaction of the water with the soil surface creates a complex flow geometry. In this study, we present the coupling of two techniques obtaining spatial data of flow depths and surface velocity measurements for water depths as low as 1 mm. Overland flow experiments were performed in the laboratory at various flow rates and slopes on two surfaces. The first surface was 120 cm by 120 cm showing three undulations of sinusoidal shape with an amplitude of 1 cm and a wavelength of 20 cm, while the second was a 60 cm by 60 cm moulded reproduction of a seedbed with aggregates up to 2 cm in size. Large scale particle image velocimetry (LSPIV) was used for velocity measurements with a sub‐centimetre spatial resolution. An instantaneous‐profile laser scanner was used to map flow depths with a sub‐millimetre spatial resolution. A sensitivity analysis of the image processing of the LSPIV showed good robustness of the method. Comparison with measurements performed with hot film anemometer and salt velocity gauge showed that LSPIV surface velocities were representative of the flow. Water depths measured with the laser scanner were also in good agreement with single‐point measurements performed with a dial indicator. Spatially‐distributed flow rates could be computed by combining both presented techniques with a mean relative error less than 20%. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
69.
Characterization of landslide ground surface kinematics from terrestrial laser scanning and strain field computation 总被引:1,自引:0,他引:1
Assessment and mitigation of the risk induced by landslide activation need an appropriate phenomenon investigation, to obtain useful information about the failure processes. The first step is the complete kinematics characterization of the landslide ground surface, by evaluating the involved displacement and deformation patterns. A dense displacement field can be obtained from comparison of a series of multi-temporal observations performed by means of terrestrial laser scanning. Subsequently, the strain field can be computed from displacement vectors. In this paper, a modified least square technique is employed to compute the strain on the nodes of a regular grid (2D approach) or on the points of a digital terrain model (3D approach). Such a computation takes into account the displacements, their spatial distribution, as well as the measurement and modelling errors. A scale factor is introduced in order to emphasize the contributions of the experimental points on the basis of their distance from each computation point, and to recognize possible scale-depending behaviours. This method has been implemented in Matlab and applied on two landslides located in the northeastern Italian Alps (Lamosano and Perarolo di Cadore). The experiments show that different kinematics can be recognized, and the presence and influence of eventual discontinuities can be revealed. 相似文献
70.
应用X射线源的航天器姿态测量 总被引:1,自引:0,他引:1
在介绍X射线源和X射线探测器、准直器的基础上,重点描述了应用X射线源测量航天器姿态参数的原理和方法。对X射线星扫描仪的结构、扫描观测X射线源方法和矩形准直器响应函数等做了介绍,较详细地论述了应用单准直器X射线星扫描仪和差分准直器X射线星扫描仪确定航天器姿态参数的测量模型,并进行了二者间的比较和分析。简单讨论了X射线星扫描仪测量建模和应用测量模型拟合航天器姿态参数的算法问题。最后,对采用编码孔径系统确定航天器姿态参数的方法做了概括性介绍。 相似文献