图像蒙版的三维场景专题信息表达

本文提出利用图像蒙版技术表现场景专题信息:通过将重要的场景专题信息以单一图像的形式罩于地形表面,形成地形"蒙版",使用户只关注蒙版即可获取所需信息,用户可以在最短时间内形成对场景专题信息的总体把握与正确认识。这种方法在一定程度上提高了用户对场景的认知效率与深度。     

Cyclone在数字校园三维激光点云数据预处理中的应用

为了高效获取精确的数字校园地形图的测量数据,通过Leica ScanStation P40对校园进行三维激光点云数据采集,并结合Cyclone中的去噪模型对点云数据进行去噪,利用“六自由度”方法和ID号对标靶进行拟合,在一定约束条件下完成点云数据的坐标匹配、拼接以及优化,得到统一坐标系下的点云数据。结果表明:优化后的点云数据精度可达到6 mm。可见处理后的点云数据能够满足数字校园地形图的高精度要求。     

Modelling of the vertical fluxes of nitric acid,ammonia, and ammonium nitrate

Results from numerical investigations regarding the exchange of HNO₃, NH₃, and NH₄NO₃ between the atmosphere and the biosphere are presented. The investigations were performed with a modified inferential method which is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these nitrogen compounds. This modified inferential method calculates the micrometeorological quantities (such as the friction velocity and the fluxes of sensible and latent heat), the height-invariant fluxes of the composed chemically conservative trace species with group concentrationsc ₁=[HNO₃]+[NH₄NO₃] (total nitrate),c ₂=[NH₃]+[NH₄NO₃] (total ammonia), andc ₃=[HNO₃]-[NH₃] as well as the fluxes of the individual nitrogen compounds. The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The modified inferential method requires only the data of wind velocity, temperature, humidity and concentrations (HNO₃, NH₃, and NH₄NO₃) measured at a reference height by stations of a monitoring network.     

激光测高数据辅助卫星成像几何模型精化处理

资源三号02星搭载了中国首个对地观测试验性激光测高载荷。借鉴目前较成熟的卫星影像区域网平差理论的基础上,结合近年来激光测高数据精度的大幅提升以及资源三号02星激光测高数据的特点,首次提出了激光测高数据辅助卫星立体影像进行成像几何模型精化处理的通用理论。首先,利用传统的区域网平差算法对所处理影像进行高精度连接点匹配处理,并对其进行无约束的自由网平差处理,获得高精度相对精度及不亚于原始成像几何模型的绝对精度;其次,根据激光测高数据3维坐标和精化后参考影像成像几何模型获取激光数据参考影像坐标;而后将参考影像坐标通过几何模型映射获取目标影像上待匹配影像坐标,通过连接点匹配算法,对待匹配目标影像坐标进行精化获取高精度像方同名点;最后,以同名点作为高程控制进行区域网平差计算,对影像成像几何模型进一步处理,获取高精度补偿参数。通过湖北、青海两测区的试验,以激光测高数据辅助卫星影像几何模型精化精度可分别达到1.97 m、3.23 m,结果表明本文提出的方法可有效提高卫星立体数据测图精度。     

Asymmetric fluxes of water and sediments in a mesotidal mudflat channel

The hydrodynamics of a small tributary channel and its adjacent mudflat is studied in Willapa Bay, Washington State, USA. Velocity profiles and water levels are simultaneously measured at different locations in the channel and on the mudflat for two weeks. The above tidal flat and channel hydrodynamics differ remarkably during the tidal cycle. When the water surface level is above the tidal flat elevation, the channel is inactive. At this stage, the above tidal flat flow is predominantly aligned along the Bay axis, oscillating with the tide as a standing wave with peak velocities up to 0.3 m/s. When the mudflat becomes emergent, the flow concentrates in the channel. During this stage, current velocities up to 1 m/s are measured during ebb; and up to 0.6 m/s during flood. Standard equations for open-channel flow are utilized to study the channel hydrodynamics. From the continuity equation, a lateral inflow is predicted during ebb, which likely originates from the drainage of the mudflat through the lateral runnels. Both advective acceleration and lateral discharge terms, estimated directly from the velocity profiles, play a significant role in the momentum equation. The computed drag coefficient for bottom friction is small, due to an absence of vegetation and bottom bedforms in the channel. Sediment fluxes are calculated by combining flow and suspended sediment concentration estimated using the acoustic backscatter signal of the instruments. A net export of the sediment from the channel is found during ebb, which is not balanced by the sediment import during flood. When the mudflat is submerged, ebb-flood asymmetries in suspended sediment concentration are present, leading to a net sediment flux toward the inner part of the Willapa Bay. Finally, a residual flow is detected inside the channel at high slack water, probably associated with the thermohaline circulation.     

罗布泊北部地区凝结水对地下水补给作用的模拟

在含盐量较高的罗布泊北部凹地,采用称重法进行了凝结水的野外监测.利用凝结水的观测资料,基于HYDRUS_1D软件,建立了一维饱和―非饱和模型来模拟预测凝结水对地下水的补给作用.研究结果表明:观测期间试筒质量多为减少,仅有3个时段试筒质量增加,表明在这3个时段有凝结水生成;凝结水对包气带的补给量占包气带水分总收入的50....     

区域空气质量数值预报系统CAPPS3在辽宁的应用

利用城市大气污染数值预报系统CAPPS的第三版(CAPPS3),经过安装、调试和本地化、自动化处理,建立起适合于辽宁的区域空气质量数值预报系统,用于预报辽宁的城市污染指数和等级以及各污染物的日均浓度分布.通过模式预报结果与监测资料的对比,发现辽宁14个主要城市SO2、NO2预报准确率的总体水平明显高于PM10.区域污染物浓度分布位置和大小的预报结果与实际情况相符,污染物小时浓度的演变也与实际风场的变化趋势保持一致,表明CAPPS3模式系统能够及时准确地预报出区域污染的形成和发展过程.     

基于三维激光扫描技术的摩崖石刻数字化重建

三维激光扫描技术通过高速激光扫描测量的方法,可高效地获取被测对象表面的三维坐标数据,具有速度快、高采样率、无接触性等优点,为快速建立不规则物体的三维重建模型提供了一种全新的技术手段。本文以GLS-1500三维激光扫描仪为基础,介绍了三维激光扫描技术在柳州市龙潭公园摩崖石刻数字化重建中的应用,实现了对摩崖石刻对象的数字化重建,具有实际应用价值。     

Updating digital elevation models via change detection and fusion of human and remote sensor data in urban environments

OpenStreetMap (OSM) currently represents the most popular project of Volunteered Geographic Information (VGI): geodata are collected by common people and made available for public use. Airborne Laser Scanning (ALS) enables the acquisition of high-resolution digital elevation models that are used for many applications. This study combines the advantages of both ALS and OSM, offering a promising new approach that enhances data quality and allows change detection: the mainly up-to-date 2D data of OSM can be combined with the high-resolution – but rarely updated – elevation information provided by ALS. This case study investigates building objects of OSM and ALS data of the city of Bregenz, Austria. Data quality of OSM is discerned by the comparison of building footprints using different true positive definitions (e.g. overlapping area). High quality of OSM data is revealed, yet also limitations of each method with respect to heterogeneous regions and building outlines are identified. For the first time, an up-to-date Digital Surface Model (DSM) combining 2D OSM and ALS data is achieved. A multitude of applications such as flood simulations and solar potential assessments can directly benefit from this data combination, since their value and reliability strongly depend on an up-to-date DSM.     

陕北延安“7.3暴雨”诱发地质灾害主要类型与特征

2013年7月3日以来,陕西延安地区百年不遇的持续性强降雨,引发了大量的崩塌、滑坡、泥流地质灾害,造成严重的财产损失和人员伤亡。通过野外实地调查,对本次持续性强降雨诱发大范围地质灾害的主要类型和特征进行了较为系统的研究。研究表明,本次持续性强降雨引发的地质灾害共计8 000余处,灾害类型主要有崩塌、滑坡和泥流,分别以小规模黄土崩塌、浅表层黄土滑坡、坡面型黄土泥流为主,以及上述灾种链生转化形成的沟谷型泥流。在持续降雨条件下,多灾种转化而成的复合型灾害是造成人员伤亡和财产损失的主要类型。