Classifier ensembles for land cover mapping using multitemporal SAR imagery

SAR data are almost independent from weather conditions, and thus are well suited for mapping of seasonally changing variables such as land cover. In regard to recent and upcoming missions, multitemporal and multi-frequency approaches become even more attractive. In the present study, classifier ensembles (i.e., boosted decision tree and random forests) are applied to multi-temporal C-band SAR data, from different study sites and years. A detailed accuracy assessment shows that classifier ensembles, in particularly random forests, outperform standard approaches like a single decision tree and a conventional maximum likelihood classifier by more than 10% independently from the site and year. They reach up to almost 84% of overall accuracy in rural areas with large plots. Visual interpretation confirms the statistical accuracy assessment and reveals that also typical random noise is considerably reduced. In addition the results demonstrate that random forests are less sensitive to the number of training samples and perform well even with only a small number. Random forests are computationally highly efficient and are hence considered very well suited for land cover classifications of future multifrequency and multitemporal stacks of SAR imagery.     

Singular value decomposition and cluster analysis as regression diagnostics tools for geodetic applications

It is well known that high-leverage observations significantly affect the estimation of parameters. In geodetic literature, mainly redundancy numbers are used for the detection of single high-leverage observations or of single redundant observations. In this paper a further objective method for the detection of groups of important and less important (and thus redundant) observations is developed. In addition, the parameters which are predominantly affected by these groups of observations are identified. This method thus complements other diagnostics tools, such as, e.g., multiple row diagnostics methods as described in statistical literature (see, e.g., Belsley et al. in Regression diagnostics: identifying influential data and sources of collinearity. Wiley, New York, 1980). The method proposed in this paper is based on geometric aspects of adjustment theory and uses the singular value decomposition of the design matrix of an adjustment problem together with cluster analysis methods for regression diagnostics. It can be applied to any geodetic adjustment problem and can be used for the detection of (groups of) observations that significantly affect the estimated parameters or that are of negligible impact. One of the advantages of the proposed method is the improvement of the reliability of observation plans and thus the reduction of the impact of individual observations (and outliers) on the estimated parameters. This is of particular importance for the very long baseline interferometry technique which serves as an application example of the regression diagnostics tool.     

CBERS-02星图像几何纠正方法试验研究

为了研究中巴地球资源卫星CCD多光谱数据规模化应用的可行性,扩大基础地理信息更新的影像资料来源,以CBERS-02星（简称02星）CCD多光谱数据的标准景为例,对2种几何纠正模型进行了对比研究,分析了3种不同基础控制资料对纠正精度的影响,并对精度评价方法进行了试验研究。在此基础上,总结形成了针对02星CCD多光谱数据1∶10万比例尺影像最为省时有效、精度最佳的几何纠正技术方法。     

国土资源卫星遥感数据应用评估系统构建

从国土资源应用出发,在“指标-模拟-评估-指标修改-模拟-评估”模式的基础上,构建了由软件系统、硬件系统、技术标准和技术方法4部分组成的评估系统,建立了较为完整的卫星数据应用评价技术方法体系,为实现在卫星研制初期就真正开展天地一体的我国卫星研制和应用的发展路线,提供了新的思路和技术体系支撑。     

月地岩矿光谱特征对比及月表信息提取方法简介

分析了月、地同类岩石矿物的光谱特征差异,对比了遥感地质信息提取方法和模型的适用性。利用Clemen-tine UV-VIS（紫外—可见光）数据,以月表典型撞击坑Aristillus（阿里斯基尔）和典型月海Humorum（湿海）为研究区,对月球表面岩矿信息提取方法进行了初步实践。     

空间信息网络服务中的数据安全策愀

以地理信息网络服务的安全策略为研究对象,根据我国空间数据生产到应用整个流程保密管理规定,研究地理空间数据在存储、分发、传输、表现以及与其他系统集成应用阶段上的安全策略,解决地理空间数据共享与空间数据安全之间的矛盾。     

使用Python函数式编程进行空间回归分析

针对使用传统的编程方式进行空间回归分析过于繁杂的问题,本文提出将Python函数式编程引入空间回归分析方法,分析和探讨脚本语言＋函数式编程方式在GIS数据分析中的推广应用前景。编程实践证明,采用Python函数式编程,结合既有的开源软件包,可以有效提高编程效率,减少代码量,将实践人员的注意力集中在问题本身。     

广域网络环境下的土地资源空间数据更新机制

在分析土地资源数据更新内部联动性较强等特点的基础上,研究了适合广域网络环境的土地资源数据更新机制。该土地资源数据更新机制采用选定工作区域、数据提取、数据下载、离线数据编辑、数据上传、数据更新等流程来具体实现。测试表明：该土地资源数据更新机制能较好地运用于县级土地资源管理部门,满足县、乡等多级土地资源管理的日常业务需求。     

应用于村镇信息自助平台的电子地图构件关键技术研究

从构件化村镇信息自助平台的低成本、易定制的特点出发,针对其中电子地图构件在地图浏览和交互查询中存在的网络负载大、响应速度慢等技术问题,研究了传统We—bGIS空间数据网络发布模式及其不足,探讨了基于AJAX、地图切片、多级缓存技术的电子地图发布解决方案,并实现了在村镇信息自助平台上的应用。     

SVG在移动地图服务中的组织与编码

根据移动地图服务的特点以及SVG的子集MobileSVG在移动设备中应用的优点,首先讨论了传统SVG地图组织模式在移动地图服务中的缺点,在此基础上提出一种新的适合移动地图服务的利用MobileSVG组织地图数据的方式,并对其组织与编码方式进行了详细的说明。