虚拟现实中交互式实时地景数据模型的组织与管理

首先介绍了虚拟现实以及用虚拟现实的手段实现动态实时地景仿真的特点及过程，针对这些特点提出了要达到充分利用虚拟现实的技术优势，更有效地实现虚拟地景的实时动态变化，以及应采用的数据模型的组织与管理方法。     

1/2000数字地面模型在高速公路勘测中的精度验证及应用

对1/2000数字地面模型DTM的高程精度进行了阐述,结合高速公路施工勘测对其进行了精度验证,并成功地应用于福建浦南高速公路施工图定测纵横断面的可靠性检查。     

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。     

Analysis of the factors affecting LiDAR DTM accuracy in a steep shrub area

The creation of a quality Digital Terrain Model (DTM) is essential for representing and analyzing the Earth in a digital form. The continuous improvements in the acquisition and the potential of airborne Light Detection and Ranging (LiDAR) data are increasing the range of applications of this technique to the study of the Earth surface. The aim of this study was to determine the optimal parameters for calculating a DTM by using an iterative algorithm to select minimum elevations from LiDAR data in a steep mountain area with shrub vegetation. The parameters were: input data type, analysis window size, and height thresholds. The effects of slope, point density, and vegetation on DTM accuracy were also analyzed. The results showed that the lowest root mean square error (RMSE) was obtained with an analysis window size of 10 m, 5 m, and 2.5 m, rasterized data as input data, and height thresholds equal to or greater than 1.5 m. These parameters showed a RMSE of 0.19 m. When terrain slope varied from 0–10% to 50–60%, the RMSE increased by 0.11 m. The RMSE decreased by 0.06 m when point density was increased from 4 to 8 points/m², and increased by 0.05 m in dense vegetation areas.     

An Approach to Single Image Automatic Orientation and Point Determination by Using Ortho-Images and a Dtm

This paper describes an approach to single image automatic orientation and point determination by using current ortho-images and a DTM, and the experience gained in its implementation. The procedure proposed automatically extracts and matches feature points in evenly distributed patches on aerial images and ortho-images. A large number of image measurements (up to several thousand) are obtained in this process and are included in a robust space resection to determine the orientation parameters of the aerial image. For point determination with a single image, a method is formalised which integrates the DTM interpolation into the space resection so that the 3D ground coordinates of the image points can be determined in a unified mathematical model. Tests and analyses of this method show that the large number of automatic image measurements relieves the requirement for complicated and precise feature extraction and matching methods. The ground points obtained from single image intersection have an accuracy of approximately 1 pixel in planimetry, which fulfils the requirement for ortho-image updating. The elevation accuracy is mainly dependent on the quality of the current DTM and the interpolation method applied to it.     

Delauuay三角网与Voronoi图在GIS中的应用研究

介绍了Delaunay三角网和Voronoi图的定义及特性，分析了其在GIS中的应用和发展方向，从理论上说明了该方法的优越性和实践的可行性，为GIS工作者在相关领域的研究指明了方向。     

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.     

提高1∶50000重力调查中测地工作精度的几种方法

介绍了1∶50 000重力勘查中提高测地工作的新思路,提出了采用GPS-RTK方法,利用CORS网站测定重力测点点位3维坐标的作业方法、消除高程异常影响而建立似大地水准面模型的方法及建立DTM数字高程模型在计算机上进行地形改正方法等。     

Generation and evaluation of multitemporal digital terrain models of the Mt. Everest area from different optical sensors

Multitemporal digital terrain models (DTM) are an important source for many purposes such as the detection of areas, which are susceptible to natural hazards such as landslides and glacial lake outburst floods, or for the examination of changes in glacier thickness. To exploit the potential of stereo satellite and aerial imagery for time series analysis, the employed methodology and software can be critical. A statistical analysis based on quartiles is presented to eliminate the influence of registration and elevation errors in DTMs. For our analysis, we used multi-temporal airborne and spaceborne stereoscopic images. The oldest images were recorded in the 1960s by the US American reconnaissance satellite Corona, while the most recent imagery are 2007 Cartosat-1 stereo scenes, along with one ASTER stereo pair. Complex panoramic distortion and limited spatial resolution resulted in the Corona and ASTER DTMs having the highest RMSEz. Due to differing acquisition techniques, applied software packages and temporal differences DTMs will never be identical. Therefore, we propose a relative vertical accuracy assessment with a master DTM. We chose the Cartosat-1 DTM as it showed the highest absolute accuracy. Inaccuracies between the master and the slave DTMs were adjusted by means of trend surfaces and outliers were successfully eliminated applying the interquartile range.