Accuracy assessment of lidar-derived digital elevation models

Despite the relatively high cost of airborne lidar-derived digital elevation models (DEMs), such products are usually presented without a satisfactory associated estimate of accuracy. For the most part, DEM accuracy estimates are typically provided by comparing lidar heights against a finite sample of check point coordinates from an independent source of higher accuracy, supposing a normal distribution of the derived height differences or errors. This paper proposes a new methodology to assess the vertical accuracy of lidar DEMs using confidence intervals constructed from a finite sample of errors computed at check points. A non-parametric approach has been tested where no particular error distribution is assumed, making the proposed methodology especially applicable to non-normal error distributions of the type usually found in DEMs derived from lidar. The performance of the proposed model was experimentally validated using Monte Carlo simulation on 18 vertical error data-sets. Fifteen of these data-sets were computed from original lidar data provided by the International Society for Photogrammetry and Remote Sensing Working Group III/3, using their respective filtered reference data as ground truth. The three remaining data-sets were provided by the Natural Environment Research Council's Airborne Research and Survey Facility lidar system, together with check points acquired using high precision kinematic GPS. The results proved promising, the proposed models reproducing the statistical behaviour of vertical errors of lidar using a favourable number of check points, even in the cases of data-sets with non-normally distributed residuals. This research can therefore be considered as a potentially important step towards improving the quality control of lidar-derived DEMs.     

土地更新调查成果与二次调查数据衔接问题的探讨

结合广西第二次土地调查工作实际,论述了在调查工作中对原土地更新调查成果的利用,对需补充、完善的调查内容逐一进行了分析和阐述,并对如何处理两次调查数据衔接中存在的问题提出了一些建议和看法。     

省级基础地理信息数据更新方法探讨

主要从更新方法、技术方案及数据共享方面讨论了省级基础地理信息数据更新的相关问题。     

室内定轨移动摄影测量控制系统设计与实现

在室内定轨移动摄影测量系统中,自动化、智能化的控制系统是其稳定可靠工作的重要保障.该摄影测量系统需要对轨道上的移动平台和摄影测量机构进行远程操作,为了实现稳定、可靠的控制,设计研发以单片机为控制核心的遥控系统;摄影测量机构是由五台非量测数码相机拼接而成,为了实现五台相机同步摄影,设计完成相机同步曝光装置.实验表明该系统...     

Signal acquisition of Luojia-1A low earth orbit navigation augmentation system with software defined receiver

Low Earth Orbit (LEO) satellite navigation signal can be used as an opportunity signal in the case of a Global Navigation Satellite System (GNSS) outage, or as ...     

一种高精度数据同步测量方法研究

在光学摄像测量中,各种数据的同步采集在事后处理中尤为重要。目前GPS授时同步技术已经很成熟,它具有精度高,操作灵活等优点,可以很好地应用于光学摄像测量中。本文深入研究了GPS OEM板授时原理,在分析了GPS OEM板芯片中RS232时间输出与1pps输出特点的基础上,基于VC开发环境下实现了GPS OEM板与计算机串口的通信,为摄像测量设置一精确的时间起点,再利用CPU时间戳进行高精度计时,这样整个测量系统就有一高精度的时钟,任一数据的产生都被标记上精确的绝对时刻,利用这些时刻信息就间接地实现了摄像测量数据的高精度同步。实验数据表明,该方法的同步精度可以达到毫秒级,可以满足光学摄像测量的同步精度要求。     

共轭面状特征的快速提取与遥感影像精确配准

使用数学形态学的"膨胀算子"对影像进行预处理,提出了一种改进的基于高斯拉普拉斯算子的面状特征提取和细化方法,并利用边界代数快速标注边界封闭的面状特征。在提取面状特征的基础上,利用奇异值分解算法,实现了基于面状质心的遥感影像匹配,进而完成精确配准。实验结果表明,与传统方法相比,此方法在速度与准确度上具有明显优势。     

超站仪技术在复杂地形测量中的应用研究

由于很多施工区域的地形较为复杂,对测量工作提出了新的要求,除改进常规测量方法外,同时需要更高效的仪器提供技术保障.本文以震后四川省九寨沟县鲜浒沟地质灾害工程1:500地形测绘项目为例,介绍了超站仪在地形测量中的应用原理,结合施工区,讨论了其实施方法、注意事项、对测量成果的重复性、复现性等问题进行了分析,提出了复杂地形测...     

基于ArcGIS的山地与非山地分类方法体系研究

在GIS空间分析和数理统计分析技术的支持下,以四川省为研究区域,基于ArcGIS平台分析提取出了绝对高程、相对高程、坡度和地面粗糙度这4类因子;然后利用这4类因子参与确立山地特征分类临界值,在此基础上,运用数理统计方法将其归并为两大类,并制定出山地分类标准体系;最后在ArcGIS软件平台下,运用栅格计算器提取出了四川省...