A combined image matching method for Chinese optical satellite imagery

Image matching is one of the key technologies for digital Earth.This paper presents a combined image matching method for Chinese satellite images.This method includes the following four steps:(1)a modified Wallis-type filter is proposed to determine parameters adaptively while avoiding over-enhancement;(2)a mismatch detection procedure based on a global-local strategy is introduced to remove outliers generated by the Scale-invariant feature transform algorithm,and geometric orientation with bundle block adjustment is employed to compensate for the systematic errors of the position and attitude observations;(3)we design a novel similarity measure(distance,angle and the Normalized Cross-Correlation similarities,DANCC)which considers geometric similarity and textural similarity;and(4)we introduce a hierarchical matching strategy to refine the matching result level by level.Four typical image pairs acquired from Mapping Satellite-1,ZY-102C,ZY-3 and GeoEye-1,respectively,are used for experimental analysis.A comparison with the two current main matching algorithms for satellite imagery confirms that the proposed method is capable of producing reliable and accurate matching results on different terrains from not only Chinese satellite images,but also foreign satellite images.

国产高分辨率遥感卫星影像自动云检测

云检测一直是卫星影像处理的难题,特别是混有地物光谱特性的薄云长期成为影像产品生产的阻碍。本文所介绍的国产高分辨率遥感卫星影像自动云检测方法能够有效克服这一难题。首先采用改进的颜色转换模型,将影像由RGB转换至HIS颜色空间,利用影像强度信息与饱和度信息生成基底图,并使用影像近红外与色调信息对其进行优化,生成修正图。然后利用直方图均衡化与双边滤波结合带限定条件的Otsu阈值分割提取纹理信息,并对修正图进行误差剔除生成云种子图。最后以HIS颜色空间的强度信息为向导,结合云种子图进行云精确提取。与不同自动、人工交互式云检测方法相比,总体精度提高了10%左右,并且能够较好地提升云检测效率。

Remote Sensing and Precision Agriculture Technologies for Crop Disease Detection and Management with a Practical Application Example

Remote sensing technology has long been used to detect and map crop diseases.Airborne and satellite imagery acquired during growing seasons can be used not only for early detection and within-season management of some crop diseases,but also for the control of recurring diseases in future seasons.With variable rate technology in precision agriculture,site-specific fungicide application can be made to infested areas if the disease is stable,although traditional uniform application is more appropriate for diseases that can spread rapidly across the field.This article provides a brief overview of remote sensing and precision agriculture technologies that have been used for crop disease detection and management.Specifically,the article illustrates how airborne and satellite imagery and variable rate technology have been used for detecting and mapping cotton root rot,a destructive soilborne fungal disease,in cotton fields and how site-specific fungicide application has been implemented using prescription maps derived from the imagery for effective control of the disease.The overview and methodologies presented in this article should provide researchers,extension personnel,growers,crop consultants,and farm equipment and chemical dealers with practical guidelines for remote sensing detection and effective management of some crop diseases.

基于注意力增强全卷积神经网络的高分卫星影像建筑物提取

从卫星遥感影像中自动提取建筑物在国民经济社会发展中具有广泛的应用价值,由于卫星遥感影像存在地物遮挡、光照、背景环境等因素的影响,传统方法难以实现高精度建筑物提取。采用一种基于注意力增强的特征金字塔神经网络方法(FPN-SENet),利用多源高分辨率卫星影像和矢量成果数据快速构建大规模的像素级建筑物数据集(SCRS数据集),实现多源卫星影像的建筑物自动提取,并与常用的全卷积神经网络进行对比。研究结果表明:SCRS数据集的提取精度接近国际领先的卫星影像开源数据集,且假彩色数据精度高于真彩色数据;FPN-SENet的建筑物提取精度优于其他常用的全卷积神经网络;采用交叉熵和dice系数之和为损失函数能够提升建筑物提取精度,最好的分类模型在测试数据上的分类总体精度为95.2%,Kappa系数为79.0%,F1分值和IoU分别达到了81.7%和69.1%。该研究可为高分辨率卫星影像建筑物自动提取提供参考。

基于高斯混合模型法的国产高分辨率卫星影像云检测

针对资源三号、高分一号等国产高分辨率卫星影像波段少、光谱范围受限的特点,提出一种通过高斯混合模型拟合影像灰度直方图从而自动获取灰度阈值的云检测算法。首先由影像灰度直方图自适应地获取高斯混合模型初始拟合参数,然后依据期望最大原则对初始参数进行调整,最后根据拟合模型中各高斯分量的分布特点,自动确定该波段影像中云与晴空之间的灰度阈值。实验表明,该算法不受限于卫星光谱范围,同时适用于含云和无云影像,检测精度较高,且不需要辅助信息和人工干预,可满足自动化生产的需要。