Building Extraction from LIDAR Based Semantic Analysis

IntroductionThanks to a large number of applications ,suchas map updating, urban planning or land useanalysis ,extraction of artificial objects ,such asbuildings ,roads fromthei mages has been an ac-tive research field for many years . Since build-ings ar…     

基于梯度互信息的光学影像和LIDAR强度图配准

LIDAR(激光雷达)数据与其相应的光学影像数据具有诸多互补性,通过配准将这两种影像数据纳入到统一的坐标系下,是实现多源数据融合处理的前提。提出一种顾及两影像空间梯度信息的互信息配准方法。利用高斯核函数构成梯度向量,并结合互信息作为相似性测度,使用粒子群优化算法作为搜索策略;设计在相同投影方式下的LIDAR强度图和航空光学影像的局部配准试验,验证了配准方法的有效性。     

基于等高线表面估计法的LIDAR数据DEM提取

本文采用了一种新的利用LIDAR数据提取数字高程模型(DEM)的方法。该方法首先由原始LIDAR数据内插生成数字表面模型(DSM),然后根据DSM等高线闭合及相交情况,将等高线分为非地面等高线和地面等高线,最后内插地面等高线生成当前DEM,并采用迭代逼近的方法进行精化,生成最终的DEM。实验证明该方法可以适用于有一定起伏的地形表面,而且该方法原理简单,计算量小,切实可行。     

基于激光雷达波形数据的点云生产

随着数据存储能力和处理速度的提高,小光斑机载激光雷达系统现在已经可以通过数字化采样来存储整个反射波形,而不仅仅是由系统提取出来的3维坐标(即离散点云).分析波形数据最重要的优点之一是可以在后处理过程中让使用者自己来提取3维坐标.一般的分解方法基于波形的局部最大值和波形的重心,或者有设备厂商提供的简单阈值法,无法获得高精度的分解结果.本文使用改进的EM脉冲检测算法来得到回波脉冲的位置和宽度,并能得到高质量的点云数据,为DSM(Digital Surface Model)和DTM(Digital Terrain Model)生产提供优质数据源.     

Automatic extraction of building roofs using LIDAR data and multispectral imagery

Automatic 3D extraction of building roofs from remotely sensed data is important for many applications including city modelling. This paper proposes a new method for automatic 3D roof extraction through an effective integration of LIDAR (Light Detection And Ranging) data and multispectral orthoimagery. Using the ground height from a DEM (Digital Elevation Model), the raw LIDAR points are separated into two groups. The first group contains the ground points that are exploited to constitute a ‘ground mask’. The second group contains the non-ground points which are segmented using an innovative image line guided segmentation technique to extract the roof planes. The image lines are extracted from the grey-scale version of the orthoimage and then classified into several classes such as ‘ground’, ‘tree’, ‘roof edge’ and ‘roof ridge’ using the ground mask and colour and texture information from the orthoimagery. During segmentation of the non-ground LIDAR points, the lines from the latter two classes are used as baselines to locate the nearby LIDAR points of the neighbouring planes. For each plane a robust seed region is thereby defined using the nearby non-ground LIDAR points of a baseline and this region is iteratively grown to extract the complete roof plane. Finally, a newly proposed rule-based procedure is applied to remove planes constructed on trees. Experimental results show that the proposed method can successfully remove vegetation and so offers high extraction rates.     

LIDAR的技术原理以及在测绘中的应用

LIDAR是一种集激光、全球定位系统（GPS）和惯性导航系统（INS）三种新技术于一身的系统，用于获得高精度、高密度的三维坐标数据，并构建目标物的三维立体模型。该技术在基础测绘DEM、DOM、DLG生产、精密工程测量、数字城市建设等领域具有广泛的应用前景，它代表了测绘技术又一个新时代的到来。     

A GIS-Based Model to Determine Site Suitability of Emergency Evacuation Shelters

In recent years, the increase in the number of hurricanes and other costal hazards in the US pose a tremendous threat to the residents of coastal states. According to the National Hurricane Center, Florida is the most vulnerable coastal state to hurricanes. Mitigation policies have been formulated to reduce mortality and provide emergency services by evacuating people from the hazard zone. Many of these evacuees, particularly the elderly or lower income populations, rely on evacuation shelters for temporary housing. Because of the cost and limited use, evacuation shelters are almost exclusively dual use shelters where the primary purpose of the facility is for some other public function (e.g. school, hospital, etc.). In 2000, the estimated shortage of public shelter spaces in Florida was about 1.5 million. The purpose of this study was to rank the existing and candidate shelters (schools, colleges, churches and community centers) available in the state based on their site suitability. The research questions examined in this study include: (1) How many candidate shelters are located in physically suitable areas (e.g. not in a flood prone area, not near hazardous facilities, etc.)?; (2) How many existing shelters are located in physically un suitable areas, but in socially suitable areas (situated in areas with demand)?; (3) How many alternative existing and/or candidate shelters with high/very high physical suitability are located near physically un suitable existing shelters and thus, may be better choices for a shelter?; and (4) How many existing shelters located in physically un suitable areas are not near alternative existing and/or candidate shelters? A Geographic Information System‐based suitability model integrating Weighted Linear Combination (WLC) with a Pass/Fail screening technique was implemented for the 17 counties of Southern Florida. It was found that 48% of the existing shelters are located in physically unsuitable areas. Out of all the candidate shelters, 57% are located in physically unsuitable areas. For 15 of the existing shelters in unsuitable locations, no alternative candidate or existing shelter with medium to high physical suitability exists within 10 miles (16.1 km).     

基于航飞LIDAR数据制作数字线划图方法探索

一些大型的工程项目在前期使用航飞LIDAR系统采集地面数据,获取了大量的三维点云数据和DOM影像数据,要制作该项目全区域的线划图,使用传统的制图方法,不仅效率低,而是几乎不可能完成该项工作。因为海量数据已经让传统的AutoCAD平台制图软件不堪重负,基于此原因,必须研究探索新的方法,就是使用GIS方法来生产线划图。     

摄影测量与遥感新技术在工程建设中的应用初探

结合摄影测量与遥感技术的发展及现状,回顾了摄影测量与遥感技术在工程建设各个方面的应用情况,并分析了近年来LIDAR,InSAR等新技术的发展趋势及其未来在我国工程勘查建设与维护中的应用潜力。     

A network‐index‐based version of TOPMODEL for use with high‐resolution digital topographic data

This paper describes the preliminary development of a network‐index approach to modify and to extend the classic TOPMODEL. Application of the basic Beven and Kirkby form of TOPMODEL to high‐resolution (2·0 m) laser altimetric data (based upon the UK Environment Agency's light detection and ranging (LIDAR) system) to a 13·8 km² catchment in an upland environment identified many saturated areas that remained unconnected from the drainage network even during an extreme flood event. This is shown to be a particular problem with using high‐resolution topographic data, especially over large appreciable areas. To deal with the hydrological consequences of disconnected areas, we present a simple network index modification in which saturated areas are only considered to contribute when the topographic index indicates continuous saturation through the length of a flow path to the point where the path becomes a stream. This is combined with an enhanced method for dealing with the problem of pits and hollows, which is shown to become more acute with higher resolution topographic data. The paper concludes by noting the implications of the research as presented for both methodological and substantive research that is currently under way. Copyright © 2004 John Wiley & Sons, Ltd.