基于易康平台的高分辨率影像在测绘生产中的地物提取

随着遥感技术的发展,遥感数据获取手段有了长足的进步。测绘部门在生产中也展开了基于高分辨率影像提取地表覆盖等信息。本论文以易康软件作为卫星遥感影像地物提取的平台,研究如何利用高分辨率遥感影像生成地表覆盖分类图,以达到测绘部门在生产中的需求。     

Landsat8和MODIS融合构建高时空分辨率数据识别秋粮作物

本文利用Wu等人提出的遥感数据时空融合方法 STDFA(Spatial Temporal Data Fusion Approach)以Landsat 8和MODIS为数据源构建高时间、空间分辨率的遥感影像数据。以此为基础,构建15种30 m分辨率分类数据集,然后利用支持向量机SVM(Support Vector Machine)进行秋粮作物识别,验证不同维度分类数据集进行秋粮作物识别的适用性。实验结果显示,不同分类数据集的秋粮作物分类结果均达到了较高的识别精度。综合各项精度指标分析,Red+Phenology数据组合对秋粮识别效果最好,水稻识别的制图精度和用户精度分别达到91.76%和82.49%,玉米识别的制图精度和用户精度分别达到85.80%和74.97%,水稻和玉米识别的总体精度达到86.90%。     

结合超像素和卷积神经网络的国产高分辨率遥感影像云检测方法

由于国产高分辨率卫星遥感影像波段少、光谱范围窄,导致传统云检测方法精度低。本文提出了基于卷积神经网络的高分辨率遥感影像云检测方法。首先采用主成分分析非监督预训练网络结构,获取待测遥感影像云特征;然后采用超像素分割方法进行影像分割;最后将检测结果影像块拼接,完成整幅影像云检测。试验效果评价表明,基于卷积神经网络的高分辨率遥感影像云检测方法不受光谱范围限制,云检测精度高,误判较少,适合国产高分辨遥感影像云检测。     

增强型多时相云检测

针对云检测在高亮度地表以及雪覆盖区域存在过度检测的问题,设计了一种不依赖热红外波段的增强型多时相云检测EMTCD(Enhanced Multiple Temporal Cloud Detection)算法。首先,利用云的光谱特征建立单时相云检测规则,并基于云、雪的光谱差异构建了增强型云指数ECI(Enhanced Cloud Index),改进了云、雪的区分能力;其次,以同一区域无云影像为参考,基于ECI指数构建了多时相云检测算法,较好地克服了单时相云检测中高亮度地表、雪和云容易混淆的问题,提高了云检测的精度;最后,选择两个典型区域的Landsat-8 OLI影像,对比分析了不同算法的云检测结果。实验结果表明:ECI指数能够有效区分云、雪,EMTCD方法的平均检测精度达到93.2%,高于Fmask(Function of mask)(81.85%)、MTCD(Multi-Temporal Cloud Detection)(66.14%)和Landsat-8地表反射率产品LaSRC(Landsat-8 Surface Reflectance Code)的云检测结果(86.3%)。因此,本文提出的EMTCD云检测算法能够有效地减少高亮度地表和雪的干扰,实现不依赖热红外波段的高精度云检测。     

星载SAR影像解译研究——以横断山脉地区为例

雷达遥感具有全天时、全天候的特点,在测绘中能够很好地弥补光学遥感的不足。随着SAR技术的不断发展,雷达影像得到了广泛的应用。然而受SAR相干侧视成像机制的影响,山区SAR影像的判读解译依然面临着巨大的挑战,制约着SAR在高山区测图、土地利用、地表覆盖等制图中的应用。本文以横断山脉地区为例,综合利用TerraSAR高分辨率升降轨影像,运用影像融合和镶嵌技术,结合实地调绘成果,对山区高分辨率星载SAR影像判读解译进行了深入研究,并最终形成了一套高效、可靠的解译流程。该判读解译流程对山区SAR影像在高山区测图、土地利用、土地覆盖制图中应用的推广具有重要的意义。     

Evaluation of image fusion methods using PALSAR,RADARSAT-1 and SPOT images for land use/ land cover classification

This research aimed to explore the fusion of multispectral optical SPOT data with microwave L-band ALOS PALSAR and C-band RADARSAT-1 data for a detailed land use/cover mapping to find out the individual contributions of different wavelengths. Many fusion approaches have been implemented and analyzed for various applications using different remote sensing images. However, the fusion methods have conflict in the context of land use/cover (LULC) mapping using optical and synthetic aperture radar (SAR) images together. In this research two SAR images ALOS PALSAR and RADARSAT-1 were fused with SPOT data. Although, both SAR data were gathered in same polarization, and had same ground resolution, they differ in wavelengths. As different data fusion methods, intensity hue saturation (IHS), principal component analysis, discrete wavelet transformation, high pass frequency (HPF), and Ehlers, were performed and compared. For the quality analyses, visual interpretation was applied as a qualitative analysis, and spectral quality metrics of the fused images, such as correlation coefficient (CC) and universal image quality index (UIQI) were applied as a quantitative analysis. Furthermore, multispectral SPOT image and SAR fused images were classified with Maximum Likelihood Classification (MLC) method for the evaluation of their efficiencies. Ehlers gave the best score in the quality analysis and for the accuracy of LULC on LULC mapping of PALSAR and RADARSAT images. The results showed that the HPF method is in the second place with an increased thematic mapping accuracy. IHS had the worse results in all analyses. Overall, it is indicated that Ehlers method is a powerful technique to improve the LULC classification.     

Land cover classification of finer resolution remote sensing data integrating temporal features from time series coarser resolution data

Land cover classification of finer resolution remote sensing data is always difficult to acquire high-frequency time series data which contains temporal features for improving classification accuracy. This paper proposed a method of land cover classification with finer resolution remote sensing data integrating temporal features extracted from time series coarser resolution data. The coarser resolution vegetation index data is first fused with finer resolution data to obtain time series finer resolution data. Temporal features are extracted from the fused data and added to improve classification accuracy. The result indicates that temporal features extracted from coarser resolution data have significant effect on improving classification accuracy of finer resolution data, especially for vegetation types. The overall classification accuracy is significantly improved approximately 4% from 90.4% to 94.6% and 89.0% to 93.7% for using Landsat 8 and Landsat 5 data, respectively. The user and producer accuracies for all land cover types have been improved.     

Use of Markov Random Fields for automatic cloud/shadow detection on high resolution optical images

In this study, we propose an automatic detection algorithm for cloud/shadow on remote sensing optical images. It is based on physical properties of clouds and shadows, namely for a cloud and its associated shadow: both are connex objects of similar shape and area, and they are related by their relative locations. We show that these properties can be formalized using Markov Random Field (MRF) framework at two levels: one MRF over the pixel graph for connexity modelling, and one MRF over the graph of objects (clouds and shadows) for their relationship modelling. Then, we show that, practically, having performed an image pre-processing step (channel inter-calibration) specific to cloud detection, the local optimization of the proposed MRF models leads to a rather simple image processing algorithm involving only six parameters. Using a 39 image database, performance is shown and discussed, in particular in comparison with the Marked Point Process approach.     

面向对象和GURLS结合的高空间分辨率遥感数据云检测

遥感信息获取过程中云是重要的干扰因素,随着国产高空间分辨率卫星数据的应用,实现数据的准确云检测对有效获取地面信息具有重要意义。本文以高分一号、高分二号多光谱影像为数据源,利用图像分割获取了同质对象,基于对象光谱、纹理和几何8种属性特征建立了规则集,以规则集为输入,利用阈值法和GURLS分类器结合进行了云检测。针对不同时相和场景的高分数据,将该方法与基于像素的最大似然法和SVM法进行了对比,结果表明该方法云提取精度均在95%以上,Kappa系数在0.9以上。     

Crop classification using biologically-inspired techniques with high resolution satellite image

Remote sensing provides a lucid and effective means for crop coverage identification. Crop coverage identification is a very important technique, as it provides vital information on the type and extent of crop cultivated in a particular area. This information has immense potential in the planning for further cultivation activities and for optimal usage of the available fertile land. As the frontiers of space technology advance, the knowledge derived from the satellite data has also grown in sophistication. Further, image classification forms the core of the solution to the crop coverage identification problem. No single classifier can prove to satisfactorily classify all the basic crop cover mapping problems of a cultivated region. We present in this paper the experimental results of multiple classification techniques for the problem of crop cover mapping of a cultivated region. A detailed comparison of the algorithms inspired by social behaviour of insects and conventional statistical method for crop classification is presented in this paper. These include the Maximum Likelihood Classifier (MLC), Particle Swarm Optimisation (PSO) and Ant Colony Optimisation (ACO) techniques. The high resolution satellite image has been used for the experiments.     

基于时刻独立脉冲耦合神经网络的高空间分辨率摇感影像分割

高空间分辨率遥感影像中地物目标内部光谱信息复杂性的增强,使得传统基于光谱特征值的数据处理方法效果不再显著,影像分割为解决这一问题提供了一种思路,成为当前高空间分辨率遥感影像处理的研究焦点.时刻独立脉冲耦合神经网络具有状态相近、空间相邻神经元相互耦合同步脉冲激发和区域之间神经元脉冲激发时刻独立两大特点,已被应用于非遥感影像分割中,并取得较好效果.本文结合高空间分辨率遥感影像特点,通过对网络参数进行实验和分析,提出一个基于时刻独立脉冲耦合神经网络的高空间分辨率遥感影像分割方法,并利用空间分辨率0.3m的航空影像进行了数据试验,将分割结果进行讨论并与现有时刻独立脉冲耦合神经网络方法和ISODATA方法分割结果进行对比分析.结果表明:时刻独立脉冲耦合神经网络在高空间分辨率遥感影像分割处理中具有很好的应用前景.     

多光谱遥感影像中云影区域的检测与修复

提出了一种有效针对多光谱遥感影像的云影检测与阴影区域修复方法。基于同一地区时相相近的两幅影像,充分利用碎云及阴影的光谱特性分别对云影区域进行融合增强,然后采用Otsu算法求解最佳阈值自动检测出云及阴影区域,根据云影的出现会引起两幅影像局部相应区域明显的亮度变化,可排除亮地物和水体的影响,建立归一化的云影密度图,在此基础上,采用线性加权组合与光谱直方图匹配相结合的方法对其加以修复,利用SPOT 4影像进行的实验表明其修复效果完全能够满足应用需要。     

利用雷达干涉数据进行城市不透水层百分比估算

人工不透水层是城市地区的重要特征.作为城市生态环境的关键指数,不透水层百分比(Impervious Surfaces Percentage, ISP)常用于城市水文过程模拟、水质面源污染及城市专题制图等研究中.本文利用ERS-1/2 重复轨道雷达干涉数据,采用分类与回归树(CART)算法探究了雷达遥感在城市ISP估算中的可行性和潜力,并与SPOT5 HRG光学遥感图像的估算结果进行了分析比较.香港九龙港岛实验区的初步研究结果表明,雷达干涉数据在城市不透水层研究中具有一定的应用潜力,特别是裸土和稀疏植被的ISP估算结果要好于光学遥感,这主要得益于雷达干涉数据(特别是长时间相干图像)在人工建筑物和裸土或稀疏植被之间具有很强的区分能力,另外,雷达干涉数据和光学遥感数据间的融合能够提高ISP估算精度.     

Smoothing and gap-filling of high resolution multi-spectral time series: Example of Landsat data

This paper introduces a novel methodology for generating 15-day, smoothed and gap-filled time series of high spatial resolution data. The approach is based on templates from high quality observations to fill data gaps that are subsequently filtered. We tested our method for one large contiguous area (Bavaria, Germany) and for nine smaller test sites in different ecoregions of Europe using Landsat data. Overall, our results match the validation dataset to a high degree of accuracy with a mean absolute error (MAE) of 0.01 for visible bands, 0.03 for near-infrared and 0.02 for short-wave-infrared. Occasionally, the reconstructed time series are affected by artefacts due to undetected clouds. Less frequently, larger uncertainties occur as a result of extended periods of missing data. Reliable cloud masks are highly warranted for making full use of time series.     

Pleiades卫星影像测图能力与精度分析试验研究

随着遥感技术的飞速发展,高分辨率卫星遥感影像越来越多地用于地理信息产品生产。本文首先介绍了SPOT系列的下一代光学遥感卫星Pleiades,通过生产试验,研究了Pleiades卫星影像稀少控制点定向情况,分析了Pleiades卫星影像立体测图的精度,并给出相关结论供Pleiades卫星影像生产实践参考。     

土地利用类型变化对环境影响的遥感信息分析

利用多时相、多分辨率的Ouickbird和SPOT图像进行土地利用变化的监测,对遥感图像上的信息进行分析,利用遥感图像进行土地利用变化信息的自动发现,结合野外调查,分析了土地利用变化对周围环境的积极效应和负面影响。实践表明,对遥感图像的信息分析结合野外调查对于发现土地利用变化对环境的影响是一种有效的方法。     

融合Landsat ETM+和MODIS数据估算高时空分辨率地表短波反照率

提出一种通过融合高空间低时间分辨率、低空间高时间分辨率地表短波反照率,来估算高时空分辨率地表短波反照率的方法。首先,利用Landsat ETM+数据,通过窄波段到宽波段的转换得到一景或多景空间分辨率较高的ETM+蓝天空短波反照率;然后,在MODIS短波反照率产品基础上,以天空光比例因子为权重,得到空间分辨率较低的MODIS蓝天空短波反照率;最后,利用STARFM(Spatial and Temporal Adaptive Reflectance Fusion Model)模型融合ETM+短波反照率的空间变化信息和MODIS短波反照率的时间变化信息,得到高时空分辨率的地表短波反照率。针对STARFM模型在异质性区域估算精度降低的问题,通过以MODIS反照率影像各像元的端元(各地类)反照率取代MODIS像元反照率来提取时空变化等信息参与STARFM模型的融合过程,达到提高异质性区域估算精度的目的。结果显示,直接利用STARFM模型估算得到的高空间分辨率地表短波反照率处在合理的精度范围内(RMSE0.02),用改进后的STARFM模型估算得到的异质性区域短波反照率和真实ETM+短波反照率间的相关系数增大。     

高分辨率遥感影像主干道路提取的感知编组方法

针对高分辨率遥感影像的道路提取受"同物异谱、同谱异物"干扰的问题,该文提出一种基于感知编组的高分辨率遥感影像主干道路自动提取方法:首先,使用Line Segment Detector算法提取影像中直线段信息。然后,利用高分辨率遥感影像上的道路几何特征对直线段进行感知编组;最后,经过长度约束得到道路信息。使用两景影像进行了主干道路提取实验。实验结果表明,两个实验中主干道路提取的完整率、正确率和检测质量都在96%以上。     

五种分割算法在高分辨率遥感图像中的适用性分析

本文将5种图像分割算法应用在高分辨率遥感图像分割上,并利用图像分割评价指标,对5种分割算法进行了对比分析,评价了各种方法的优缺点,讨论了它们在高分辨率遥感图像分割中的适用性,明确了不同分割方法的适用条件。实验结果表明,改进的分水岭分割法与JSEG分割法在高分辨率遥感图像分割中的适用性比较强,对大小斑块分割结果都比较好,而其他3种方法不能兼顾不同等级的斑块。     

Analysing the advantages of high temporal resolution geostationary MSG SEVIRI data compared to Polar Operational Environmental Satellite data for land surface monitoring in Africa

Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth's natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on-board MSG with an imaging capability every 15 min which is substantially greater than any temporal resolution that can be obtained from existing Polar Operational Environmental Satellite (POES) systems currently in use for environmental monitoring. Different areas of the African continent were affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher temporal resolution cloud-free (<5 days) measurements of the environment as compared to existing POES systems. SEVIRI MSG 5-day continental scale composites will enable rapid assessment of environmental conditions and improved early warning of disasters for the African continent such as flooding or droughts. The high temporal resolution geostationary data will complement existing higher spatial resolution polar-orbiting satellite data for various dynamic environmental and natural resource applications of terrestrial ecosystems.