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991.
近年来,随着地面3维激光扫描技术的迅速发展,该技术在历史风貌保护工作中的应用越来越广泛。本文以表面复杂的优秀历史建筑为主要研究对象,重点研究海量点云数据管理方法以及激光扫描建模数据制作流程,并以"上海市不可移动文物管理地理信息系统"为例,介绍了针对激光扫描建模数据的管理系统与应用平台。 相似文献
992.
刘金辉 《测绘与空间地理信息》2013,(12):142-145
地面3维激光扫描仪是一种可进行全自动高精度立体扫描的先进仪器。其特点是可大面积高分辨率地快速获取被测对象表面的3维坐标数据,且所获取的数据具有实时、动态、高密度、高精度等优点。因而,激光扫描测量仪器的精度对工程应用的影响以及对3维点云模型的建立和精度影响至关重要。文章针对瑞格公司所生产的VZ400扫描仪在测量时,距离、入射角度、目标颜色几个因素对精度产生的影响进行研究。利用平面拟合的方法分析精度,得出了随着距离的增加,入射角的增大,会导致地面3维激光扫描仪测量精度降低的定性分析结论. 相似文献
993.
Recent research has started to focus on how prolonged periods of sub‐threshold flows may be capable of imparting structural changes that contribute to increased bed stability. To date, this effect (termed ‘stress history’) has been found to be significant in acting to increase a bed's critical shear stress at entrainment threshold. However, it is supported by only limited, qualitative and often speculative information on the mechanisms of this stabilization process in grade‐specific studies. As such, this paper uses high resolution laser scanning to quantitatively ascertain the granular mechanics underpinning the relationship between stress history and entrainment threshold for beds of a range of grain size distributions. Employing a bed slope of 1/200, three grain size distributions with median grain sizes (D50) of 4·8 mm [uniform (σg = (D84/D16)0.5 = 1·13; bimodal (σg = 2·08); and, unimodal (σg = 1·63)] were exposed to antecedent stress histories of 60 and 960 minutes duration. Antecedent shear stress magnitude was set at 50% of the critical shear stress for the D50 when no stress history period was employed. Two laser displacement scans of the bed surface (approximate area 100 mm × 117 mm) were taken, one prior to the antecedent period and one after this period, so that changes to surface topography could be quantified (resolution of x = 0·10 mm, y = 0·13 mm and z = 0·24 mm). Rearrangement of bed surface structure is described using statistical analysis and two‐dimensional (2D) semi‐variograms to analyse scaling behaviour. Results reveal vertical settlement, changes to bed roughness and particle repositioning. However, the bed grain size distribution influences the relative importance of each mechanism in determining stress history induced bed stability; this is the focus of discussion in this paper. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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地面3维激光扫描仪是通过高速激光扫描测量的方法,大面积、高分辨率地快速获取被测对象表面的3维坐标数据,根据3维数据可以构建3维模型,为古建筑保护等提供数据依据。本文对地面3维激光扫描技术进行了简单探讨,通过具体实例研究分析其在古建筑保护中的应用。 相似文献
997.
In this paper the development of the technology of the laser scanning is summarized. The principles of laser range scanning are introduced. Based on the laser scanning technology and methods, which are investigated by the authors to survey deposit volume, a surveying system is developed and a practical application is performed. It is shown that the laser-scanning technology has obvious advantages such as measurement precision, automation and visualization of observed data in comparison with the traditional methods. As a result, labor intensity is relieved obviously and work efficiency is promoted. 相似文献
998.
Methods for feature detection in laser scanning data have been studied for decades ever since the emergence of the technology. However, it is still one of the unsolved problems in LiDAR data processing due to difficulty of texture and structure information extraction in unevenly sampled points. The paper analyzes the characteristics of Laplacian of Gaussian (LoG) Filter and its potential use for structure detection in LiDAR data. A feature detection method based on LoG filtering is presented and experimented on the unstructured points. The method filters the elevation value (namely, z coordinate value) of each point by convolution using LoG kernel within its local area and derives patterns suggesting the existence of certain types of ground objects/features. The experiments are carried on a point cloud dataset acquired from a neighborhood area. The results demonstrate patterns detected at different scales and the relationship between standard deviation that defines LoG kernel and neighborhood size, which specifies the local area that is analyzed. 相似文献
999.
Luca Carturan Giovanni A. Baldassi Aldino Bondesan Simone Calligaro Alberto Carton Federico Cazorzi Giancarlo Dalla Fontana Roberto Francese Alberto Guarnieri Nicola Milan Daniele Moro Paolo Tarolli 《Geografiska Annaler: Series A, Physical Geography》2013,95(1):79-96
Smaller glaciers (<0.5 km2) react quickly to environmental changes and typically show a large scatter in their individual response. Accounting for these ice bodies is essential for assessing regional glacier change, given their high number and contribution to the total loss of glacier area in mountain regions. However, studying small glaciers using traditional techniques may be difficult or not feasible, and assessing their current activity and dynamics may be problematic. In this paper, we present an integrated approach for characterizing the current behaviour of a small, avalanche‐fed glacier at low altitude in the Italian Alps, combining geomorphological, geophysical and high‐resolution geodetic surveying with a terrestrial laser scanner. The glacier is still active and shows a detectable mass transfer from the accumulation area to the lower ablation area, which is covered by a thick debris mantle. The glacier owes its existence to the local topo‐climatic conditions, ensured by high rock walls which enhance accumulation by delivering avalanche snow and reduce ablation by providing topographic shading and regulating the debris budget of the glacier catchment. In the last several years the glacier has displayed peculiar behaviour compared with most glaciers of the European Alps, being close to equilibrium conditions in spite of warm ablation seasons. Proportionally small relative changes have also occurred since the Little Ice Age maximum. Compared with the majority of other Alpine glaciers, we infer for this glacier a lower sensitivity to air temperature and a higher sensitivity to precipitation, associated with important feedback from increasing debris cover during unfavourable periods. 相似文献
1000.
Michael Wiedenbeck Roxana Bugoi M. John M. Duke Tibor Dunai Jacinta Enzweiler Mary Horan Klaus Peter Jochum Kathryn Linge Jan Košler Silke Merchel Luiz F.G. Morales Lutz Nasdala Roland Stalder Paul Sylvester Ulrike Weis Arnaud Zoubir 《Geostandards and Geoanalytical Research》2012,36(4):337-398
Advances in the chemical and isotopic characterisation of geological and environmental materials can often be ascribed to technological improvements in analytical hardware. Equally, the creation of novel methods of data acquisition and interpretation, including access to better reference materials, can also be crucial components enabling important breakthroughs. This biennial review highlights key advances in either instrumentation or data acquisition and treatment, which have appeared since January 2010. This review is based on the assessments by scientists prominent in each of the given analytical fields; it is not intended as an exhaustive summary, but rather provides insight from experts of the most significant advances and trends in their given field of expertise. In contrast to earlier reviews, this presentation has been formulated into a unified work, providing a single source covering a broad spectrum of geoanalytical techniques. Additionally, some themes that were not previously emphasised, in particular thermal ionisation mass spectrometry, accelerator‐based methods and vibrational spectroscopy, are also presented in detail. 相似文献