人卫激光测距望远镜系统的指向修正

利用实测数据分析了人卫激光测距望远镜系统常用的两种指向修正模型(球谐函数模型与Mount Strom lo支架模型)的精度和稳定性。结果表明,两种模型均能达到较好的拟合精度,但Mount Strom lo支架模型系数间大多不相关,其稳定性明显优于球谐函数模型。     

A laser scanning-based method for fast estimation of seismic-induced building deformations

Monitoring damaged buildings in an area where an earthquake has occurred requires the use of techniques which provide rapid and safe measurements even in emergency conditions. In particular, remote sensing techniques like terrestrial laser scanning (TLS) can satisfy these requirements, since they produce very dense point clouds in little time and also allow an accurate geometric modeling of observed buildings. Nevertheless, strong constraints on TLS data acquisition geometry, such as acquisition distance and incidence angles, typically characterize an area in seismic emergency conditions. In order to correctly interpret the data, it is necessary to estimate errors affecting TLS measurements in these critical conditions. A reliable estimation can be achieved by means of experiments and numerical simulations aimed at quantifying a realistic noise level, with emphasis on reduction of artifacts due to data acquisition, registration and modeling. This paper proposes a data analysis strategy in which TLS-based morphological maps computed as point-to-primitive differences are created. The method can be easily used for accurate surveying in emergency conditions. In order to demonstrate the proposed method in very diverse situations, it was applied to rapidly detect deformation traces in the San Giacomo Roncole Campanile (Modena), the Asinelli tower (Bologna) and the Cantalovo Church (Verona), three buildings damaged by the Mw 5.9 Emilia Romagna 2012 earthquake (Italy).     

Single tree biomass modelling using airborne laser scanning

Accurate forest biomass mapping methods would provide the means for e.g. detecting bioenergy potential, biofuel and forest-bound carbon. The demand for practical biomass mapping methods at all forest levels is growing worldwide, and viable options are being developed. Airborne laser scanning (ALS) is a promising forest biomass mapping technique, due to its capability of measuring the three-dimensional forest vegetation structure. The objective of the study was to develop new methods for tree-level biomass estimation using metrics derived from ALS point clouds and to compare the results with field references collected using destructive sampling and with existing biomass models. The study area was located in Evo, southern Finland. ALS data was collected in 2009 with pulse density equalling approximately 10 pulses/m². Linear models were developed for the following tree biomass components: total, stem wood, living branch and total canopy biomass. ALS-derived geometric and statistical point metrics were used as explanatory variables when creating the models. The total and stem biomass root mean square error per cents equalled 26.3% and 28.4% for Scots pine (Pinus sylvestris L.), and 36.8% and 27.6% for Norway spruce (Picea abies (L.) H. Karst.), respectively. The results showed that higher estimation accuracy for all biomass components can be achieved with models created in this study compared to existing allometric biomass models when ALS-derived height and diameter were used as input parameters. Best results were achieved when adding field-measured diameter and height as inputs in the existing biomass models. The only exceptions to this were the canopy and living branch biomass estimations for spruce. The achieved results are encouraging for the use of ALS-derived metrics in biomass mapping and for further development of the models.     

基于3维激光扫描的智能社区建设

数字城市建设风起云涌,智慧城市引领发展潮流。地理信息技术从2维发展到3维把城市的抽象化变为可视化。智能社区只是把智慧城市微缩到社区,变宏观管理为微观管理,变粗犷管理为精细管理。这是未来社区管理的发展趋势,智能化将成为衡量居民幸福指数的重要标志。     

简述利用ALS70机载激光雷达生产数据产品

机载激光雷达（LiDAR）是近10年出现的高新技术之一,能迅速获取密集的地面3维数据,并广泛应用于各个领域。本文主要介绍了我院通过试验,获取及处理ALS70机栽激光雷达点云数据的方法。     

三维激光扫描技术在变形监测中的应用

随着激光扫描硬件设备的升级优化,三维激光扫描仪与其他设备更加易于集成,数据采集简单迅速,可实时处理点云数据,快速构建三维模型.与传统变形监测方法相比,将三维模型用于变形监测更加全面,自动化、智能化强度高,实时性好,且精度高.本文简单介绍了三维激光扫描系统的国内外研究现状、工作原理和分类,与传统变形监测方法作了比较,详细分析了三维激光扫描系统在变形监测中的应用.     

基于地面三维激光扫描技术的滑坡模型监测与预测

地面三维激光扫描技术可以高精度、高密度、高速度、非接触地测量滑坡表面三维空间坐标,从而得到滑坡模型地表的整体变形资料.文章结合滑坡模型试验,利用灰色模型GM(1,1)对模型中提取的两个监测点的三维坐标位移进行预测,经由实测值与预测值比较、误差检验、图形对比等得出结论:灰色模型可以应用于长期的滑坡控制点三维坐标位移预测中.     

先验知识引导的车载激光扫描点云道路信息提取

文章研究利用先验知识从车载激光扫描点云数据中提取道路信息:使用改进的不规则三角网渐进加密滤波方法对点云滤波;将地面点投影到水平面上,利用行车轨迹提取道路主轴线;然后生成高程差分特征图像,以主轴线为基准进行平面生长获得道路面;并根据反射强度,进一步获得道路边界和道路标识线等信息.最后使用两景车载激光扫描点云数据验证了方法的可行性和有效性.     

变窗口均值限差法的点云噪声滤除方法

利用三维点云数据建模的准确与否很大程度上依赖于点云滤波效果的好坏,通过对滤波方法的研究,可以提供尽量准确的地面点云数据.文章利用C#高级编程语言,结合OpenGL三维图形库对三维激光点云数据进行噪声滤波处理;将三维激光点云投影到格网内的拟合平面上,通过变窗口均值限差法对高差、坡度关键参数进行了分析对比,确定出合适滤波参数,模拟表达实际地形的原貌.实验证明,变窗口的均值限差法可以滤除绝大部分噪声,对于紧邻地面的部分噪声,可以通过进一步拟合最小二乘曲面或加入先验信息等方法去除.该方法不仅能够有效去除噪声,而且还能较大程度地保留地形的特征信息.     

基于EIV模型的稳健估计

EIV（error-in-variables）模型同时考虑观测向量和系数矩阵的误差,自提出以来便得到广泛应用。目前针对EIV模型的整体最小二乘解法（TLS）假设观测值仅含有偶然误差,当观测值存在粗差时其解并不是最优的。文中通过选定合适的权函数,结合加权整体最小二乘迭代算法,导出基于EIV模型的稳健整体最小二乘迭代解法（RTLS）。线性拟合实验表明,文中方法能对粗差进行定位,且估计量受粗差影响较小,具有稳健性。