摄影测量数据库的设计与建立

摄影测量数据库主要存储和管理数字地图成果数据，包括数字高程模型数据（DEM）、数字矢量地图数据（DLG）、数字影像地图数据（DOM）和数字栅格地图数据（DRG）。本文主要介绍了摄影测量数据库的设计、建立以及应用分析等内容。     

二维线划图中建筑物檐口高自动提取方法

为了更好地满足智慧城市建设中对自动获取建筑物精确檐口高的需求,提出了一种基于极大值边缘信息量的高程初值提取方法,实现了二维线划图与边缘影像在檐口位置的初始套合,在此基础上通过广义点摄影测量迭代求解精确檐口高。实验结果表明,该方法可以全自动地恢复二维线划图中的建筑物檐口高,达到分米级精度,不仅提供了一种生产三维线划图的技术方法,而且对于建筑物三维建模、人工地物自动提取等技术的发展和进步也具有推动意义和参考价值。     

典型高陡边坡高位地质灾害调查及评估

高陡边坡顶部往往难以通达,高位灾害体的判识评估是灾害防治中的难点问题。本文针对某典型高陡边坡,采用无人机低空摄影辅助调查,查明了陡坡危岩体和坡顶变形体地质特征;应用数码摄影测量技术,获取了边坡岩体结构和灾害体几何特征等信息。通过潜在失稳岩体稳定性分析,失稳岩体运动轨迹、冲击能量分析,评价边坡地质灾害危险性;桥梁、路基、棚洞3种构造物型式易损性和灾害发生后经济损失分析表明,棚洞结构最优,若采用其他结构需对边坡主动加固。     

基于多基线数字近景摄影测量测制1:500地形图的应用研究

主要阐述了基于多基线数字近景摄影测量技术测制1∶500地形图的的可行性、成图流程和成图精度等,并阐述了生产过程中各个方面的技术难点及其解决方法和建议。试验结果表明,该方法可行、精度可靠,但是有其局限性。     

无人机在重大地质灾害应急调查中的应用

传统的地质灾害应急调查受限于地形、天气等外界条件,不能快速全面地获取灾害的详细信息,而无人机具有灵活性强、时效性高和不受复杂地形影响等特点,在地质灾害应急调查中有独特的优势。本文以“6·24”新磨村滑坡和“10·11”白格滑坡为例,阐述了无人机数据获取及处理流程,重点介绍了无人机获取的数字地形产品在地质灾害精确描述、定性及定量分析中的应用。结果表明：无人机摄影测量技术为重大地质灾害应急调查提供了更加科学高效的现场影像采集和遥感成果处理及应用方案,为应急救灾工作的顺利实施及分析研判提供了重要数据支撑,科学有效地保证了现场施工救援人员的安全。     

利用高分辨率影像建立三维虚拟校园——以"数字成都理工大学"为例

以数字化校园工程———“数字成都理工大学”为例,探讨利用航空影像和数字摄影测量技术,获取基础空间地理信息的方法及途径。并采用三维建模软件Cyber C ity对建筑物进行三维建模。而对于复杂地物,采用三维地理信息系统IMAGIS软件建立单个模型,从而实现了成都理工大学校区的三维可视化虚拟重建和漫游。实践证明,利用数字摄影测量技术和遥感影像,能够有效地获取大范围区域地表地物的三维信息,并快速地建立地面模型和三维景观。     

Application of Structure‐from‐Motion photogrammetry to river restoration

Structure‐from‐Motion (SfM) photogrammetry is now used widely to study a range of earth surface processes and landforms, and is fast becoming a core tool in fluvial geomorphology. SfM photogrammetry allows extraction of topographic information and orthophotos from aerial imagery. However, one field where it is not yet widely used is that of river restoration. The characterisation of physical habitat conditions pre‐ and post‐restoration is critical for assessing project success, and SfM can be used easily and effectively for this purpose. In this paper we outline a workflow model for the application of SfM photogrammetry to collect topographic data, develop surface models and assess geomorphic change resulting from river restoration actions. We illustrate the application of the model to a river restoration project in the NW of England, to show how SfM techniques have been used to assess whether the project is achieving its geomorphic objectives. We outline the details of each stage of the workflow, which extend from preliminary decision‐making related to the establishment of a ground control network, through fish‐eye lens camera testing and calibration, to final image analysis for the creation of facies maps, the extraction of point clouds, and the development of digital elevation models (DEMs) and channel roughness maps. The workflow enabled us to confidently identify geomorphic changes occurring in the river channel over time, as well as assess spatial variation in erosion and aggradation. Critical to the assessment of change was the high number of ground control points and the application of a minimum level of detection threshold used to assess uncertainties in the topographic models. We suggest that these two things are especially important for river restoration applications. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

非量测相机在南极大比例尺成图中的应用

非量测相机在各个领域得到了广泛的应用,而应用于航空摄影测量中还是一个新的尝试。本文通过在南极航摄中的应用试验,阐明了非量测相机应用于大比例尺测图成图是可行的,精度能够满足工程建设的需要。     

Combined Digital Photogrammetry and Time-of-Flight Laser Scanning for Monitoring Cliff Evolution

Although cliffs form approximately 75% of the world's coastline, the understanding of the processes through which they evolve remains limited because of a lack of quantitative data on the morphological changes they undergo. In this paper the combination of terrestrial time-of-flight laser scanning with high-resolution digital photogrammetry is examined to generate high-quality data-sets pertaining to the geomorphic processes governing cliff development. The study was undertaken on a section of hard rock cliffs in North Yorkshire, UK, which has been monitored over a 12-month period. High-density, laser-scanned point clouds have been used to produce an accurate representation of these complex surfaces, free from the optical variations that degrade photographic data. These data-sets have been combined with high-resolution photographic monitoring, resampled with the fixed accuracies of the terrestrial laser survey, to generate a new approach to recording the volumetric changes in complex coastal cliffs. This has led to significant improvements in the understanding of the activity patterns of coastal cliffs.