几种常见数字航摄仪的分析与比较

数字航摄仪是直接获取高精度数字影像的重要手段之一。文中介绍当前国际上3种主流数字航摄仪ADS40（Airborne Digital Sensor 40）、DMC（Digital Mapping Camera）及Ultra CamD（UCD）,并分析三者的成像原理及关键技术,同时从多个方面对三者进行评估和比较。     

数码航测中多拼CCD相机同步曝光方法及其实验分析

多拼相机组合成等效大面阵相机,可以形成宽角视场,对于数码航测具有重要意义,其中同步曝光是其核心技术之一.本文研究了一种光耦继电器为核心部件的同步曝光方法,对同步曝光的性能进行了实验,利用统计分析的方法进行了数据分析,验证了相对于传统的电磁继电器方案的优越性,实验表明可以满足大比例尺数码航测的要求.     

协同式柔性信息化航测生产管理模型

针对信息化测绘体系下,新兴航测技术更迭加快,航测生产中技术装备和软件扩充、基础地理信息数据增多、技术人员结构化、生产流程复式化导致传统管理模式已无法满足业务发展需求的问题,该文立足航测生产单位实际,分析信息化航测生产发展现状,提出构建协同式柔性航测生产管理模型的方法。基于该模型,设计开发信息化航测生产管理系统。最后,通过四川省遥感信息测绘院信息化测绘生产试点示范基地建设进行应用实践。     

数字航空摄影有关技术的分析探讨

随着数字成像技术的发展,数字航空摄影仪必将逐步取代胶片航空摄影仪,在胶片航空摄影中取得的一些航摄设计的技术参数将不再适用于数字航空摄影。本文基于数字航摄的特点,从航摄任务出发,就数字航空摄影时如何较合理的选择相应的数字相机和进行航摄设计等问题进行了初步分析和探讨。     

Relative Radiometric Normalisation - performance testing of selected techniques and impact analysis on vegetation and water bodies

In this paper, six image-based Relative Radiometric Normalization (RRN) techniques were applied to normalize the bi-temporal Landsat 5 TM data-set. RRN techniques do not require any atmospheric and ground information at the time of image acquisition. The target image for the year 2009 was normalized in such a way that it resembled the atmospheric and sensor conditions similar to those under which the reference image of the same season for the year 1990 was acquired. Among the selected methods applied, it was found that the Iteratively Reweighted Multivariate Alteration Detection (IR-MAD) method performed better, based on the error statistic. The IR-MAD technique was found to be advantageous as it identified a large set of true time-invariant pixels automatically from the change background using iterative canonical component analysis. The technique also stretches the values of Normalized Difference Vegetation Index and Normalized Difference Water Index and may help to distinguish different vegetation and water bodies better.     

基于Skyline三维模型重建的关键方法及其应用

对Skyline三维模型重建过程中的数据预处理及建模关键技术进行了研究;并基于该平台,充分利用已有的传统的地理空间数据,将其应用到武汉大学信息学部局部校区的三维模型重建中,取得了较好的效果。     

论宽角航摄仪的精度、效率与成像质量

针对影响航空摄影测量精度、作业效率和成像质量的各种因素,该文提出了内外方位元素可清晰分离的航摄仪检校场建设方法,实现了航摄仪内方位元素的高精度检校。以此为基础,设计和实践了一种满足现有航测生产要求的高性能宽角航摄仪,该设备具有旁向视场角超过80°、稳定曝光频率2Hz、自动感知飞行速度和地形高、依摄影测量规则自动决定曝光间隔等能力。数万平方千米的生产实践表明:宽角航摄仪影像色彩自然,全局纹理清晰,支持在大速高比环境下航空摄影,其综合作业效率超过当今国际品牌航摄仪2倍以上。     

Assessing the transferability of airborne laser scanning and digital aerial photogrammetry derived growing stock volume models

Three-dimensional (3D) data from airborne laser scanning (ALS) and, more recently, digital aerial photogrammetry (DAP) have been successfully used to model forest attributes. While multi-temporal, wall-to-wall ALS data is not usually available, aerial imagery is regularly acquired in many regions. Thus, the combination of ALS and DAP data provide a sufficient temporal resolution to properly monitor forests. However, field data is needed to fit new forest attribute models for each 3D data acquisition, which is not always affordable. In this study, we examined whether transferability of growing stock volume (GSV) models may provide an improvement in the efficiency of forest inventories updating. We used two available ALS datasets acquired with different characteristics in 2009 and 2010, respectively, generated two DAP point clouds from imagery collected in 2010 and 2017, and utilized field data from two ground surveys conducted in 2009 and 2016-2017. We first analyzed the stability of point cloud derived metrics. Then, Support Vector Regression models based on the most stable metrics were fitted to assess model transferability by applying them to other datasets in four different cases: (1) ALS-ALS, (2) DAP-DAP temporal, (3) ALS-DAP and (4) ALS-DAP temporal. Some metrics were found to be enough stable in each case, so they could be used interchangeably between datasets. The application of models to other datasets resulted in unbiased predictions with relative root mean square error differences ranging from -8.27% to 14.59%. Results demonstrated that 3D-based GSV models may be transferable between point clouds of the same type as well as point clouds acquired using different technologies such as ALS and DAP, suggesting that DAP data may be used as a cost-efficient source of information for updating ALS-assisted forest inventories.     

基于图文工作流定制的LUPMIS的设计与实现

本文从土地利用规划管理信息系统(LUPMIS)的业务需求出发,研究了图文工作流的组织模型、过程模型、功能模型与信息模型,分别提出了"地图操作角色"、"图文活动"、"图文功能"以及"图文信息"。针对传统工作流中数据表单和流程处理过程相对固定的缺陷,给出了实现数据表单和业务流程动态定制的关键技术。最后在.NET、ArcObject和Oracle 9.2i平台下,实现了基于图文工作流定制的昆明市LUPMIS。实践表明,基于图文工作流定制的LUPMIS在很好地集成工作流与GIS的同时,减少了业务环节改变带来的开发人员的开发量和系统管理员维护量。     

Performance of dense digital surface models based on image matching in the estimation of plot-level forest variables

Recent research results have shown that the performance of digital surface model extraction using novel high-quality photogrammetric images and image matching is a highly competitive alternative to laser scanning. In this article, we proceed to compare the performance of these two methods in the estimation of plot-level forest variables. Dense point clouds extracted from aerial frame images were used to estimate the plot-level forest variables needed in a forest inventory covering 89 plots. We analyzed images with 60% and 80% forward overlaps and used test plots with off-nadir angles of between 0° and 20°. When compared to reference ground measurements, the airborne laser scanning (ALS) data proved to be the most accurate: it yielded root mean square error (RMSE) values of 6.55% for mean height, 11.42% for mean diameter, and 20.72% for volume. When we applied a forward overlap of 80%, the corresponding results from aerial images were 6.77% for mean height, 12.00% for mean diameter, and 22.62% for volume. A forward overlap of 60% resulted in slightly deteriorated RMSE values of 7.55% for mean height, 12.20% for mean diameter, and 22.77% for volume. According to our results, the use of higher forward overlap produced only slightly better results in the estimation of these forest variables. Additionally, we found that the estimation accuracy was not significantly impacted by the increase in the off-nadir angle. Our results confirmed that digital aerial photographs were about as accurate as ALS in forest resources estimation as long as a terrain model was available.     

国土资源电子政务中GIS与工作流的集成应用研究

图文一体化已成为电子政务信息化建设的一项基本要求。基于模型级图文一体化的集成方式基本上解决了电子政务建设过程中GIS图形系统和工作流审批系统的开发相对独立的问题。模型级图文一体化的集成方式代表了GIS与工作流技术集成的发展趋势。本文以江苏省国土资源电子政务基础平台中GIS与工作流的集成为实例,研究了该电子政务平台中GIS的体系结构及GIS功能的划分,并从数据集成、用户权限角色集成、功能集成、用户界面集成等四个方面对国土资源电子政务平台实现图文的一体化。并在模型层次对GIS与工作流的集成进行了初步尝试。     

Modelling and predicting the spatial dispersion of skin cancer considering environmental and socio-economic factors using a digital earth approach

ABSTRACT

Almost all causative factors of diseases depend on location. The Digital Earth approach is suitable for studying diseases globally. Geospatial information systems integrated with statistical models can be used to model the relationship between a disease and its causative factors. Through modelling, the most important causative factors can be extracted and the epidemiology of the disease can be observed. In this paper, skin cancer (the most common type of cancer) has been modelled based on its causative factors, including climate factors, people's occupations, nutrition habits, socio-economic factors, and usage of chemical fertiliser. To fit the model, a data framework was first designed, and then data were gathered and processed. Finally, the disease was modelled using Generalised Linear Models (GLM), a statistical model based on the location of the factors. The results of this study identify the most important causative factors together with their relative priority. Furthermore, a model was used to predict the change in skin cancer occurrences caused by a change in one of its causative factors. This work illustrates the ability of the model to predict disease occurrence. Thus, by using this Digital Earth approach, skincancer can be studied in all the key countries around the world.     

新一代数字地球平台与“数字中国”技术体系架构探讨

本文系统分析和总结了Google Earth的四大特点,及为地球科学研究、"数字地球"和"数字中国"的发展所带来的影响和启迪,提出了数字地球平台(DEP)的概念,并针对"数字中国"的建设,提出了建立"数字中国"的数据交换标准(DCML),提出了全新的以地学信息浏览器/空间信息服务器(G/S)结构为主的下一代数字地球、数字中国的技术体系架构,进一步对"数字中国"技术体系架构应遵循的原则进行了论述,对"数字中国"建设和应用服务进行了展望。     

基于无人飞行器遥感的矿区沉陷控制及景观规划研究

空间信息在矿区陆面演变的研究中发挥着重要的作用,但由于矿区特殊的地理地貌特点,传统的空间数据获取方法无法满足;无人机遥感系统方便、快捷,本文探讨了基于无人机遥感系统的矿区空间信息获取及其在矿区沉陷控制与景观规划建设中的应用。     

Augmented virtual environment: fusion of real-time video and 3D models in the digital earth system

ABSTRACT

An Augmented virtual environment (AVE) is concerned with the fusion of real-time video with 3D models or scenes so as to augment the virtual environment. In this paper, a new approach to establish an AVE with a wide field of view is proposed, including real-time video projection, multiple video texture fusion and 3D visualization of moving objects. A new diagonally weighted algorithm is proposed to smooth the apparent gaps within the overlapping area between the two adjacent videos. A visualization method for the location and trajectory of a moving virtual object is proposed to display the moving object and its trajectory in the 3D virtual environment. The experimental results showed that the proposed set of algorithms are able to fuse multiple real-time videos with 3D models efficiently, and the experiment runs a 3D scene containing two million triangles and six real-time videos at around 55 frames per second on a laptop with 1GB of graphics card memory. In addition, a realistic AVE with a wide field of view was created based on the Digital Earth Science Platform by fusing three videos with a complex indoor virtual scene, visualizing a moving object and drawing its trajectory in the real time.     

基于EPS的建设工程测绘自动化系统设计与实现

结合广州市城市规划勘测设计研究院GIS基础空间数据生产实际,介绍了将工程测绘系统与掌上电脑测绘系统相结合,完全实现建设工程测绘内外业自动化的全过程,以及按照GIS数据质量标准,实现GIS数据动态更新的系统设计。     

沙漠蝗群对印巴边境植被的影响及其未来可能发展趋势

2020年初非洲东北和印巴边境沙漠蝗群席卷多个国家,大面积农田及自然植被被啃食,是什么气候条件促成了此次沙漠蝗灾?距离中国最近的印巴边境蝗群成为研究以及社会关注的热点,蝗灾对当地植被的影响如何?其发展趋势如何?从气候学上分析,蝗灾历史上是否曾经或者未来是否向印度东边迁飞而进入中国呢?本研究利用长时间序列的卫星遥感数据和气象气候观测数据,对沙漠蝗群可能扩展趋势进行了分析。研究结果表明:(1)由于沙漠蝗群的啃食,2020年1月和2月,在蝗群分布区大面积植被区的归一化植被指数较常年大幅度下降,2月(2月3日数据)的啃食面积较1月明显扩大;(2)发生在2018年5月和10月两次印度洋飓风和2019年12月强热带风暴等几个罕见气旋给非洲和阿拉伯半岛带来的强降水,是本次非洲-西亚蝗灾的形成重要原因;(3)从影响沙漠蝗群起飞的气温和沙漠蝗虫适合的降水条件来看,历史上或未来沙漠蝗群迁徙到印度东边的机会很少,进入中国的可能性非常小。     

浅谈大比例尺数字测图的应用及其减少误差的方法

结合工作实际对大比例尺数字测图的方法、误差来源及减少误差的方法进行讨论,并提出一些在实际工作中减少误差的方法。