航空摄影测量技术在海岛礁测绘的应用

在完成海岛像控测量、野外调绘、空三加密、内业测图等航空摄影测量技术流程,测绘比例尺1:10000海岛地形图,制作相应的数字高程模型、正射影像图等产品的基础上,总结了航测技术应用于海岸、海岛地形测绘的技术方法、作业流程,并将航测成果与常规海岸地形测量成果进行比对,得出了航测成果精度能够满足<海道测量规范>要求,航测技术可...     

小区域消费级无人机倾斜摄影像控点布设及建模精度研究

像控点布设是无人机倾斜摄影施测阶段的重要环节,直接决定后期三维实景模型的精度。本文面向校园等小区域环境,利用消费级单镜头多旋翼无人机航摄系统获取影像数据,重点设计了不同像控点布设方案,基于全自动数据处理系统进行空三加密及三维模型的构建,并对模型成果进行精度分析,为实际工作中小区域像控点的布设提供建议和指导。     

The dynamic characteristics and migration of a pyramid dune

The results of wind tunnel experiments and field observations show that when the intersection angle between airflow direction and dune crest (ridge) line is > 30°, a reverse vortex is formed. Because of the convergence of sand streams from the windward and lee slopes at the crest, sand accumulates in the crestal region, causing vertical growth. Nevertheless, studies also show that the common asymmetry of the two slopes of a dune may significantly influence the evolution of arms of a pyramid dune. The migration rates of pyramid dunes are mediated by the interplay of their arms moving transversely and the vertical growth in response to the variations in wind regimes. Comparing the effects of airflow transverse to a given arm with longitudinal airflow, it is indicated that the transverse airflow is more significant in controlling the arms of pyramid dunes. The whole body of the studied pyramid dune, particularly the upper quarter section, migrated SE direction during the monitoring period. The patterns of wind erosion and deposition change alternately with seasonal variations in wind directions. The W, NE and SE sides undergo constant erosion, deposition and both erosion and deposition, respectively. The results of long-term monitoring of a pyramid dune show that southerly winds, resulting from a local circulation, markedly affect the transverse migration of the whole pyramid dune.     

无人机航摄技术在大比例尺测图中的应用研究

以无人机航摄技术在大比例尺(1∶1 000、1∶500)地形图测绘中的应用为研究目的,采用固定翼无人机平台,搭载非量测型数码相机,于河北某矿区进行航摄大比例尺地形图制作实验,通过外业实测点位数据对测图高程及平面精度进行评估。实验结果表明:通过严控误差影响因素无人机航摄技术可以满足1∶1 000比例尺测图精度要求,1∶500比例尺测图精度无法满足。最后,基于精度评定数据对误差产生的原因进行了深入分析与探讨,为无人机航摄技术测绘大比例尺地形图应用的可行性及可靠性提供了经验。     

无地面控制点卫星摄影测量探讨

为解决无地面控制点的卫星摄影测量(简称无控定位)这一国际难题,对国外具有代表性的几个"全球连续覆盖模式"光学摄影测量卫星的主要技术参数特征以及无控摄影测量模式、技术措施等方面进行了系统归纳,尽管各系统在无控定位上作了种种努力,但与美国1∶50 000比例尺制图标准(水平位置误差12m,垂直高程误差6m)相比,都存在一定距离,该文认为其不足的关键在于对星敏感器测姿误差的处理上。该文还特别介绍了天绘一号卫星工程达到这一标准的主要学术与技术措施,并列举了国内外检查点检测精度一致性的实例。     

无人机在冰川变化监测中的应用——以唐古拉山小冬克玛底冰川为例

近年来,无人机技术发展迅速。无人机的灵活、便携、超高分辨率等特性使其在冰川变化监测上具有很好的发展前景。论文以青藏高原腹地的唐古拉山小冬克玛底冰川为例,首次在海拔5400 m以上的地区开展了无人机航测,通过非冰川区的基岩对2019年7月20日、2019年9月27日和2020年7月16日3期航测产品进行相对校正,分析了小冬克玛底冰川在物质平衡年和消融期内的变化情况,并进一步讨论了无人机在冰川区观测时所遇到的问题及其优势,以期为后续研究提供参考。结果表明:利用无人机技术能够实现冰川在消融期内的末端、面积以及高程变化监测,并对冰川的细部特征进行分析,适合于小区域单条冰川的变化监测。     

The first ISPRS software contest for computer-assisted teaching (CATCON)

The first ISPRS software contest for computer-assisted teaching, CATCON, took place on July 12, 1996 at the ISPRS Congress in Vienna. The main objective of the contest was to promote the development and dissemination of good/user-friendly software packages for computer-assisted teaching. Ten software packages and one data set from six countries were nominated. All the software and the data set were demonstrated at the contest, and prizes were given to three software packages and to one data set.     

Documentary Evidence of an Economic Character as a Source for the Study of Meteorological and Hydrological Extremes and their Impacts on Human Activities

This paper deals with documentary evidence of an economic character as a proxy for direct study of meteorological and hydrological extremes. Taxation records and reports of those who administrated domains and estates are described with respect to information about meteorological and hydrological extremes. Based on data from eight domains or estates from Moravia (in the Czech Republic), frequency series of floods and convective storms (including hailstorms) were developed for the period 1650–1849. One example of disastrous weather, which took place on 10 August 1694 in the Pern?tejn domain, is used to demonstrate the potential for such studies of the intensity of extremes and their impact on human activities. The importance of economic evidence in the instrumental period is shown through tax rebate data contingent upon hailstorm damage in Moravia (1896–1906). The benefits of employing documentary economic evidence for historical climatology and the study of the impact of meteorological and hydrological extremes on human activities are discussed.     

Use of terrestrial photogrammetry for monitoring and measuring bank erosion

This paper examines the use of terrestrial photogrammetry as a technique for measuring bank erosion in a rapidly changing fluvial environment. It has been recognized that there are a number of advantages when applying photogrammetric techniques to geomorphological situations. In this study the enhancement of spatial sampling combined with the ability to capture additional information, such as soil moisture, on film, is of particular importance in enabling the identification of specific processes involved in bank erosion as well as detailed volumetric analysis of losses. Metric terrestrial photography was taken of the river bank on several dates, and data were abstracted by the use of analytical photogrammetry. This enabled the generation of digital terrain models from which morphological and volumetric changes could be assessed. © 1997 John Wiley & Sons, Ltd.     

基于Cesium的WebGIS倾斜三维平台的实现

由于传统的二维GIS平台日渐式微,地理信息技术发展的速度越来越快,需要精度更高、表现力更好的三维GIS平台以及相应的解决方案。本文阐述了以Cesium开源前端库为依托,通过倾斜三维模型作为基础数据,实现三维WebGIS平台建设的解决方案,同时通过实例对三维平台的功能进行说明。