Data fusion and classifier ensemble techniques for vegetation mapping in the coastal Everglades

This study examined the applicability of data fusion and classifier ensemble techniques for vegetation mapping in the coastal Everglades. A framework was designed to combine these two techniques. In the framework, 20-m hyperspectral imagery collected from Airborne Visible/Infrared Imaging Spectrometer was first merged with 1-m Digital Orthophoto Quarter Quads using a proposed pixel/feature-level fusion strategy. The fused data set was then classified with an ensemble approach based on two contemporary machine learning algorithms: Random Forest and Support Vector Machine. The framework was applied to classify nine vegetation types in a portion of the coastal Everglades. An object-based vegetation map was produced with an overall accuracy of 90% and Kappa value of 0.86. Per-class classification accuracy varied from 61% for identifying buttonwood forest to 100% for identifying red mangrove scrub. The result shows that the framework is promising for automated vegetation mapping in the Everglades.     

资源三号卫星数据矿山地质环境调查研究

采矿引起的一系列矿山环境问题不仅威胁到人们生命财产安全,而且严重影响和制约着经济的发展,也引发了一系列社会问题和矛盾。本文运用资源三号卫星遥感数据,以黑龙江省鹤岗市为例,解译鹤岗市矿山地质环境,并对遥感图像解译成果进行综合分析研究。     

Integrating global land cover products for improved forest cover characterization: an application in North America

Six widely used coarse-resolution global land cover data-sets – Global Land Cover Characterization (GLCC), Global Land Cover 2000 (GLC2000), GlobCover land cover product (GlobCover), MODIS land cover product (MODIS LC), the University of Maryland land cover product (UMD LC), and the MODIS Vegetation Continuous Fields tree cover layer (MODIS VCF) disagree substantially in their estimates of forest cover. Employing a regression tree model trained on higher-resolution, Landsat-based data, these multisource multiresolution maps were integrated for an improved characterization of forest cover over North America. Evaluated using a withheld test sample, the integrated percent forest cover (IPFC) data-set has a root mean square error of 11.75% – substantially better than the 17.37% of GLCC, 17.61% of GLC2000, 17.96% of GlobCover, 15.23% of MODIS LC, 19.25% of MODIS VCF, and 15.15% of UMD LC, respectively. Although demonstrated for forest, this approach based on integration of multiple products has potential for improved characterization of other land cover types as well.     

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.     

Digital map conflation: a review of the process and a proposal for classification

This article is centred on analysing the state of the art of the conflation processes applied to geospatial databases (GDBs) from heterogeneous sources. The term conflation is used to describe the procedure for the integration of these different data, and conflation methods play an important role in systems for updating GDBs, derivation of new cartographic products, densification of digital elevation models, automatic features extraction and so on. In this article we define extensively each conflation process, its evaluation measures and its main application problems and present a classification of all conflation processes. Finally, we introduce a bibliography which the reader may find useful to further explore the field. It tries to serve as a starting point and direct the reader to characteristic research in this area.     

北京一号小卫星数据的城市景观格局监测分析——以徐州市城区为例

为了推进北京一号小卫星遥感数据在城市景观生态研究中的应用,针对其全色影像4m分辨率、多光谱影像32m分辨率的特点,试验分析北京一号小卫星影像在城市景观格局变化中的应用效果和特点。通过对不同分类器的比较,选择支持向量机分类器对多光谱影像、全色影像、全色与多光谱融合影像三个数据集进行景观组分分类,结果表明,全色与多光谱融合影像的分类精度最高。利用多时相、多光谱遥感数据统计分析了城市景观组分与格局变化,表明32m空间分辨率的多光谱影像可以用于城市景观格局变化和土地覆盖变化分析。本文全面试验和分析评价了北京一号多分辨率数据在城市景观格局研究中的应用效果。通过对同一年份全色影像和多光谱影像计算的景观格局指标的分析表明,全色数据能更有效地描述景观详细信息,多光谱数据可展现城市景观的整体格局,而融合后对景观格局分析能够获得优于单一数据的效果。试验和分析表明,北京一号小卫星4m全色高分辨率影像和32m多光谱数据的波段组合,能从不同尺度揭示城市景观格局和变化过程。     

古遗址区形迹特征的影像融合信息识别分析——以陕西省五陵原遗址为例

本研究以陕西省汉五陵原为研究区域,基于高分辨率影像(DOM航片)、多光谱影像(ALOS多光谱影像)和Quickbird融合影像数据,对五陵原遗址区结构性线状特征信息进行了提取。结果表明:融合后使影像隐含的空间纹理得到明显增强。用Gram-Schmidt方法的DOM和ALOS多光谱+NDVI融合影像,清晰地反映了遗址区的结构性线状特征;而Canny算法的边缘检测,能很好地提取遗址区显性和大量隐性的线状特征,对古遗迹的解译具有重要指示意义。     

网上全景多视点实时浏览与快速传输系统

设计了一个面向虚拟旅游场景的网上全景多视点实时漫游与传输系统。该虚拟旅游系统是基于Flash3D技术进行了构架设计,对海量虚拟旅游全景图片的传输模式和传输策略进行了优化调度,从而使得虚拟旅游场景的网上浏览和传输变得更为流畅。该优化调度策略在湛江虚拟旅游系统中得到了很好的运用。     

小波基及其参数对遥感影像融合图像质量的影响

IHS和小波变换结合的融合方法已成为多源遥感影像信息聚合的有效途径,但小波基与小波分解层数等参数对影像融合质量影响的很多细节需进一步研究。该文以SPOT遥感影像为数据,在Matlab软件环境下进行小波簇、不同序号小波基及分解层数的图像融合,用信息熵、平均梯度和标准偏差3指标对融合图像的质量进行评价。结论如下:第1层小波分解的融合图像质量差异不大;其余小波分解层数下融合影像的质量因小波基而异,如coif5s、ym5、dmey对小波分解层数不敏感,db1、bior3.1则具有分段响应的敏感特征,其中,rbio3.1在小波分解层数为4时,融合图像失真;不同簇的小波基对融合图像质量的影响也各异。结果表明,小波基等参数的选取直接影响到遥感影像融合的效果。     

“针孔”模拟成像下的单航空影像与LiDAR点云配准

以摄影测量共线方程为严格配准模型,提出了一种引入针孔成像模拟过程的单张航空影像LiDAR点云配准迭代方法,共分为3个阶段:第一,利用航空影像内参数及初始外方位元素对LiDAR点云针孔模拟成像,生成与航空影像空间分辨率、几何形变相接近且具有相同幅面大小的透视影像-LiDAR深度影像;第二,以梯度互信息作为影像相似性测度依据,实施影像金字塔、分块处理策略实现LiDAR深度影像与航空影像几何变换参数快速估计,进而依据估计参数及LiDAR深度影像、激光脚点投影关系建立LiDAR点云航空影像概略相关;第三,以LiDAR点云影像概略相关下的近似同名像点为观测值,以像点梯度互信息为权重,实施摄影测量空间后方交会计算获得优化的影像外方位元素,生成新的LiDAR深度影像并重复上述过程,直至满足给定的迭代计算条件,实现单张航空影像与LiDAR点云数据的自动空间配准。实验表明,本文方法配准精度达亚像素级且自动化程度高。