Geometric Integration of Aerial and High-Resolution Satellite Imagery and Application in Shoreline Mapping

This paper investigates the geopositioning accuracy achievable from integrating IKONOS and QuickBird satellite stereo image pairs with aerial images acquired over a region at Tampa Bay, Florida. The results showed that the accuracy is related to a few factors of imaging geometry. For example, the geopositioning accuracy of a stereo pair of IKONOS or QuickBird images can be improved by integrating a set of aerial images, even just a single aerial image or a stereo pair of aerial images. Shorelines derived from the IKONOS and QuickBird stereo images, particularly the vertical positions, are compared with the corresponding observations of water-penetrating LiDAR and water gauge stations and proved that differences are within the limit of the geopositioning uncertainty of the satellite images.     

不同高分辨率遥感图像融合技术特征比较

简要回顾了图像融合技术的起源和发展情况。对图像融合的概念与基础理论作了阐述,剖析了其优缺点和使用领域。通过6种融合方法对杭州市滨江区QuickBird正射影像及数字化地形图进行了融合,并对融合图像进行了效果评价,结果表明,所有融合图像的方差和熵都大于配准后的图像,融合后图像的信息量大为增加。     

Mapping forest and peat fires using hyperspectral airborne remote-sensing data

The characteristic features of airspace hyperspectral remote sensing (RS) are considered in order to develop classification techniques for relevant images. Currently available approaches to constructing classifiers (computational procedures) are described for recognizing natural and anthropogenic objects in hyperspectral images. We confirm that the methods under development are effective enough with the reduced dimensionality of the feature space of original spectra and the decreased sample volumes in supervising procedures for the selected object classes. Data from joint hyperspectral and aerial photography provide examples of the spectral distributions smoke of different intensities from forest and peat fires in the presence and absence of fire sources, for the smoke coverage of water surfaces, and for the forest vegetation without ignition sources within a selected area. The results obtained in the supervising procedures are used for pattern recognition and scene analysis in airborne images obtained for the test areas during forest-fire season.     

SPOT、QuickBird卫星遥感数据提取东沙岛植被信息的比较

基于植被的光谱特征,利用监督分类、植被指数(NDV I)和目视解译等方法,分别用SPOT-5、Q u ickB ird高分辨率卫星遥感影像对东沙岛植被信息进行提取,并作了比对分析。研究结果表明:利用高分辨率遥感图像对东沙岛等小型岛屿的植被信息提取是可行的;SPOT-5多光谱数据具备了提取小型海岛植被信息、掌握其植被覆盖状况的能力;与SPOT-5多光谱数据相比,Q u ickB ird多光谱数据在植被精细分类信息的提取方面更具优势。     

自由像片重叠区域的确定及拼接

在获得低空航空遥感数据之后,通常需要将所获取的大量影像数据在没有地面控制的条件下进行概略拼接。由于低空航空遥感数据存在较大的旋偏角,其重叠区域的确定不同于简单的重叠确定。运用计算机图形学的方法,提出了一种确定重叠区域的通用算法,并采用改进SZELISKI算法进行影像拼接。试验结果表明：提出的通用算法能很好的确定影像重叠区域,且适用于多张影像重叠;改进的SZELISKI算法,其运算结果更加符合人的视觉习惯,影像过渡自然,重影现象最小。     

空间分辨率对水深遥感反演的影响分析

遥感水深反演中空间分辨率的影响是一个重要的科学问题。本文使用东岛的QuickBird和WorldView-2多光谱影像及实测水深点进行实验研究,实验使用了原始空间分辨率（2.4/2m）以及4种降空间分辨率（4m,8m,16m和32m）的影像,使用相同的水深控制点开展水深遥感反演,并对水深反演结果使用相同的检查点进行精度验证。实验结果表明,随着空间分辨率由2.4/2m降低至4m,8m和16m,水深遥感反演的精度呈现出逐渐提高的趋势,进一步降低空间分辨率则会导致水深反演精度下降。当影像空间分辨率为16m时,水深反演结果误差最小且与实测水深值相关性最高,此时两景影像的水深反演平均相对误差分别21.2%和13.1%,相对于最大值分别降低了14.7%和2.9%;平均绝对误差分别为2.0m和1.4m,相对于最大值分别降低了1.0m和0.5m。本文研究结果为水深遥感反演研究与应用中遥感数据的选择提供了参考。     

面向对象的产品物料清单多视图定义技术研究

为了实现产品全生命周期中的物料清单(BOM)数据的一致性和协同性，在阐述了企业中BOM数据的主要使用部门的基础上，分析了企业BOM的主要使用类型、功能需求和技术特点。提出了BOM视图和BOM视图空间的基本定义，讨论了BOM视图空间的主要类型。基于单一数据源的思想，采用面向对象的建模方法，定义了BOM对象模型和BOM对象的主要视图类型及其关键属性。该技术的应用对于实现CIMS环境下的BOM信息集成具有重要的意义。     

3D空间航片纹理源的纹理映射问题

随着数字三维城市建设的快速推进,传统的纹理获取方法已不能满足快速建模的要求。提出了一种基于航片纹理源的3D空间纹理映射方法,基于摄影测量学相关理论,通过设计算法,实现了建筑物侧面纹理的自动匹配。实验证明,这种方法简单、高效,适用于大面积建筑物3D建模。     

利用ADS40相机快速生成正射影像图的方法研究

介绍了ADS40相机快速生成正射影像图的方法,即利用高精度POS设备能直接定向测图的特点,省去空三T序,利用POS解算出的外方位元素和自动提取的DEM进行正射影像纠正,结合实际生产项目对成图精度进行了分析。试验结果表明,ADS40相机应用于航测生产可大幅度缩短成图周期,利用本文的生产方法可以满足正射影像图精度要求,并节省大量时问,适用于应急测绘保障。     

Tracking stormwater discharge plumes and water quality of the Tijuana River with multispectral aerial imagery

Spatial–temporal characteristics and environmental factors regulating the behavior of stormwater runoff from the Tijuana River in southern California were analyzed utilizing very high resolution aerial imagery, and time-coincident environmental and bacterial sampling data. Thirty nine multispectral aerial images with 2.1-m spatial resolution were collected after major rainstorms during 2003–2008. Utilizing differences in color reflectance characteristics, the ocean surface was classified into non-plume waters and three components of the runoff plume reflecting differences in age and suspended sediment concentrations. Tijuana River discharge rate was the primary factor regulating the size of the freshest plume component and its shorelong extensions to the north and south. Wave direction was found to affect the shorelong distribution of the shoreline-connected fresh plume components much more strongly than wind direction. Wave-driven sediment resuspension also significantly contributed to the size of the oldest plume component. Surf zone bacterial samples collected near the time of each image acquisition were used to evaluate the contamination characteristics of each plume component. The bacterial contamination of the freshest plume waters was very high (100% of surf zone samples exceeded California standards), but the oldest plume areas were heterogeneous, including both polluted and clean waters. The aerial imagery archive allowed study of river runoff characteristics on a plume component level, not previously done with coarser satellite images. Our findings suggest that high resolution imaging can quickly identify the spatial extents of the most polluted runoff but cannot be relied upon to always identify the entire polluted area. Our results also indicate that wave-driven transport is important in distributing the most contaminated plume areas along the shoreline.     

Changes of coral communities over 35 years: Integrating in situ and remote-sensing data on Saint-Leu Reef (la Réunion, Indian Ocean)

Monitoring coral reef communities at a decadal scale is necessary to understand and project their dynamics to provide a basis for reef management in light of disturbances and climate change. Complementing infrequent and localised in situ observations, time-series of aerial photographs and remotely sensed satellite images provide a means of monitoring the position and extent of reef-top coral communities, vegetation and abiotic substrata at the whole reef scale. The aim of the present study was to map such changes on Saint-Leu Reef (La Réunion) between 1973 and 2007. The period included two cyclones (1989, 2002) and one severe bleaching event (2002). Vertical images of the reef were recorded in five aerial photographs (1973, 1978, 1989, 1997, and 2003) and two Quickbird satellite images (2002, 2006) during that time. Quantitative in situ observations of parts of the reef-top were also available both to document ecological and substratum characteristics that produce the color and texture observable in the photos and satellite images. Coral communities were mapped on all images using manual delineation of polygons identified according to color and texture contrast. The 2006 Quickbird image was used as the mapping base and 15 types of coral communities were identified from a reef survey conducted in 2007. This hierarchical typology used coral growth forms, live and dead coral cover, macro-algae, substratum (sand, rubble and platform) and, to a lesser extent, coral taxonomy. The polygons at date t were over-laid onto image t − 1 across the whole series and their boundaries were manually edited to match the pattern on the earlier image. Labelling of polygons was guided by field-survey data and maps. For coral-dominated patches, six successive pairs of maps from 1973 to 2006 were compared to produce ‘coral community change maps’ for that period. Despite the multiple disturbance events, the coral community distribution and composition in 2006 on Saint-Leu Reef did not display major differences compared to 1973. This suggests a high degree of coral resilience at the site, led by rapid recovery of compact branching corals. The mapping techniques overcame challenges due to different image quality and the sparsity of in situ observations in time and space. Our results demonstrate the potential for further application of reef monitoring protocols based on complementary in situ and remote-sensing data to help understand the dynamics of reef-top coral reef communities and geomorphology over years to decades.     

海岸带水边线等高条件控制下的航空影像外部定向

提出了一种基于海岸带水边线等高条件的航空影像外部定向方法,该方法将局部区域水边线上各点的高程值相等作为控制条件,在立体像对的外部定向中,引入这些等高点,和其他平高控制点一起参加平差,计算立体像对的绝对方位元素.实验证明,该方法能够有效地提高航空影像的外部定向精度,尤其是高程的定位精度,提高了海岸带地形的测图精度.     

Wave direction measured by four different systems

During a March 1977 experiment, four systems were used to provide wave-direction information offshore of Mission Beach, CA: a synthetic aperature radar (SAR) carried aboard a NASA CV990 aircraft, a coastal imaging radar, a pressure-gauge array offshore, and aerial photography aboard two aircraft. The coastal radar, aerial photographs, and SAR provided wave images. From the coastal radar images and the aerial photographs, the direction and length of the principal wavetrains were measured by a manual analysis. The SAR images were also processed using an FFT to give two-dimensional wave spectra. The array at the Naval Ocean Systems Center (NOSC) tower was used to provide directional wave spectra. Scatter diagrams are presented, which intercompare the measurements from these four systems. In addition, radar image spectral information is compared with the array spectra. The intercomparison of the data from these four systems shows good agreement among the imaging systems. Between the imaging systems and the pressure array there is agreement for the most prominent wavetrains and disagreement for several cases where multiple wavetrains from different directions but with similar periods are present.     

Remote analysis of changes in the number of small thermokarst lakes and their distribution with respect to their sizes in the cryolithozone of Western Siberia, 2015

Regularities of changes in the number of thermokarst lakes in the cryolithozone of Western Siberia have been studied using multitemporal satellite images. The studies were conducted on 33 test sites selected in different landscape zones of the study area with the use of 134 cloud-free Landsat images obtained during warm months in the period from 1973 to 2013. It is shown that the total number of new lakes is significantly (almost 20 times) higher than the number of disappeared lakes. The area of newly formed thermokarst lakes is, on average, 22 times smaller than the size of disappearing lakes. Therefore, one can assume that the rapid growth in the number of small thermokarst lakes that is observed under the conditions of global warming will lead to an increase in methane emissions into the atmosphere in permafrost zones in the Arctic territories. Results of remote sensing of statistical distribution of small thermokarst lakes with respect to their sizes are given. The studies were performed on eight test sites selected in different permafrost zones of Western Siberia. The size of small lakes was determined according to QuickBird super-high resolution satellite images. It is shown that histograms of distribution of lakes with respect to their sizes allow their approximation by power and exponential functions, which can be used for modeling and predicting the dynamics of thermokarst methane emission in permafrost zones.     

大倾斜航空摄影图像地理坐标赋予方法

为了获取大倾斜航空摄影图像中目标点的位置,提出了参照基准图像,基于改进的6参数仿射变换模型进行几何纠正的方法。该方法对基准图像和大倾斜航空摄影图像分别进行角点检测,然后进行配对处理,配对后的相邻角点进行分组后,构建Delaunay三角网,在局部范围内分别进行仿射变换。实验表明,对大倾斜航空摄影图像赋予地理坐标能够达到较好的结果。     

Estimation of vegetation structure and its anthropogenic transformation by processing QuickBird images: A case study of the Novosibirsk Akademgorodok

A new method for forest mapping utilizing high-resolution satellite images has been developed by a case study of the Novosibirsk Akademgorodok. Guided classifications of summer and fall QuickBird images, overlay operations, and grid density analysis form the background for this method. This method was used to construct maps of forest density and quantitative ratios of softwood to hardwood tree species. A comparison with the traditional geobotanical mapping has demonstrated several advantages of the remote sensing approach (including the precise definition of boundaries as well as high accuracy of estimation of the canopy density and the ratio of soft- to hardwood tree species) and shortcomings. The proposed method is not intended to replace but rather supplement and quantitatively improve the traditional approach. Matching the integral forest map and the corresponding geological-geomorphological map makes it possible to reveal the correlations between specific geomorphological features of the area, the composition of surface deposits, and the forest stand structure and thus estimate the degree of anthropogenic transformation in the natural forest ecosystems. In turn, this may be useful when organizing ecosystem monitoring.     

基于改进TIN的空中三角测量模型较差显示

为在空中三角测量模型较差检测中形象快速标注误差超限点、超限区域,直观揭示误差全局区域联系,给空中三角测量补加连接点提供指引,提高空中三角测量作业效率和精度,结合逐点插入法和数据分块思想改进Delaunay三角网构网算法,提出了一种空中三角测量模型较差平面显示方法,利用Delaunay三角网的优良网拓扑关系显示超限点并推...     

Correcting underwater images distorted by surface waves

An experiment on the correction of underwater images distorted by waves at the air-water interface was conducted using a laboratory modeling installation intended for experimental examination of light and image transfer across a water surface covered with waves. A digital color camera was used for the simultaneous formation of the image of the underwater test object through the disturbed surface and of the superimposed glitter pattern. Both images are spectrally separated. Processing the glitter pattern makes it possible to obtain the values of the surface slopes at a limited number of points and to use these slopes for retrieval of image fragments. The total corrected image is formed by integration of about 300 partially corrected fragments. This image is close to that obtained through a wave-free water surface.     

基于多源数据的海岸线综合提取及时空演变研究

海岸线由于受陆海交互影响，其形态与功能的变化复杂。近些年，遥感技术和地理信息系统（Geographic Information System，GIS）的广泛应用为研究海岸线提供了重要基础。本文基于多源数据，以南沙湾周边区域为样本区，将人机交互目视解译法和聚焦剖面法运用于不同类别海岸线的提取，并重点分析南沙区8 个时期海岸线的时空演变。结果表明：聚焦剖面法对于自然岸线的识别更具科学性，而基于无人机正射影像和快鸟卫星（QuickBird）影像，运用人机交互目视解译法能够更加贴合实际情况。对于分辨率较低的卫星影像，可结合两种方法提取人工岸线。从南沙区海岸线的数据分析显示，1990—1995年、2005—2012 年海岸线长度变化最剧烈；2012年之前海岸线向海域快速拓展，围填海区域快速增加，后期逐渐降速至相对稳定。南沙区海岸线时空变迁与不同发展阶段人类活动干扰高度关联。在农业发展阶段，万顷沙的联围工程推动岸线向南拓展；在工业发展阶段，龙穴岛等区域的开发导致岸线进一步向海扩张；在新城营造阶段，生态修复岸线增长，局部岸线向内陆收缩，岸线利用趋于精细化。     

基于无人机与卫星图像的大型绿藻孔石莼(Ulva pertusa)遥感估算研究

卫星影像是监测海面漂浮绿藻的重要数据源, 但是混合像元的存在使得绿藻提取存在一定的误差。想要实现近海区域底栖绿藻的精细监测, 需要解决绿藻亚像素覆盖度的问题。本文以厘米级分辨率无人机数据的绿藻提取结果为基准, 通过分析Landsat卫星影像绿藻光谱, 建立绿藻亚像素覆盖度与多种植被指数和多个特征波段反射率的反演模型。结果表明, 蓝、绿、红波段反射率与绿藻亚像素覆盖度呈现较好的线性关系, 随着绿藻亚像素覆盖度递增, 蓝、绿、红波段反射率的值均递减。将蓝、绿、红波段的三种绿藻亚像素覆盖模型进行验证, 发现绿波段反射率所建立的反演模型具有更高的准确性, 决定系数、均方根误差、平均相对误差分别为0.92%、0.07%、10.85%。本文所建立的模型可以估算大型绿藻亚像素覆盖度, 实现Landsat卫星影像对大型绿藻的精细监测。