基于像方特征点的多视影像最小二乘匹配

为了能得到更精确的影像初始值,进行高精度的影像匹配,本文分别选取了两种物方多视匹配模型和不同匹配策略、不同约束条件下的影像粗匹配结果作为初始值进行最小二乘精匹配。实验结果表明物方匹配模型可以提供很精确的初始值,而金字塔、视差和共线方程共同约束下的最小二乘匹配精度更高,可靠性、鲁棒性及稳定性更好,验证了结合合理的匹配策略和约束方法的最小二乘优化可以将匹配精度达到1／10000精度。     

浅谈VirtuoZo和MapMatrix在3D产品中的应用

主要论述了数字摄影测量系统MapMatrix和VirtuoZo的一些异同点。     

Enrichment of topographic road database for the purpose of routing and navigation

With growing demand on multi-purpose or multi-modal navigation, the route calculation needs to traverse semantically enriched road networks for different transportation modes. Currently, operational route planning algorithms reveal rather limited performances or their potential for comprehensive applications are constrained by the unavailable or insufficient interoperation among the underlying geo-data that are separately maintained in different spatial databases. To overcome this limitation, a novel approach has been proposed to integrate the routing-relevant information from different data sources, which involves three processes: (1) automatic matching to identify the corresponding road objects between different datasets; (2) interaction to refine the automatic matching result; and (3) transferring the routing-relevant information from one data-set to another. In process (1), the Delimited Stroke Oriented algorithm is employed to achieve the automatic data matching between different datasets, which has revealed a high matching rate and certainty. However uncertain matching problems occur in areas where topological conditions are too complicated or inconsistent. The remaining unmatched or wrongly matched objects are treated in process (2), with the help of a series of interaction tools. On the basis of refined matching results after the interaction, process (3) is dedicated to automatic integration of the routing-relevant information from different data sources.     

Tracking of facial deformations in multi-image sequences with elimination of rigid motion of the head

The paper deals with measurement of human facial deformations from synchronized image sequences taken with multiple calibrated cameras from different viewpoints. SIFT (Scale Invariant Feature Transform) keypoints are utilized as image feature points in the first place to determine spatial and temporal correspondences between images. If no temporal match is found for an image point by keypoint matching, then the tracking of the point is switched to least squares matching provided the point has one or more spatial corresponding points in the other views of the previous frame. For this purpose, a new method based on affine multi-image least squares matching is proposed where multiple spatial and temporal template images are simultaneously matched against each search image and part of the spatial template images also change during adjustment. A new method based on analyzing temporal changes in the image coordinates of the tracked points in multiple views is then presented for detecting the 3-D points which move only rigidly between consecutive frames. These points are used to eliminate the effect of rigid motion of the head and to obtain the changes in the 3-D points and in the corresponding image points due to pure deformation of the face. The methods are thoroughly tested with three multi-image sequences of four cameras including also quite large changes of facial deformations. The test results prove that the proposed affine multi-image least squares matching yields better results than another method using only fixed templates of the previous frame. The elimination of the effect of rigid motion works well and the points where the face is deforming can be correctly detected and the true deformation estimated. A method based on a novel adaptive threshold is also proposed for automated extraction and tracking of circular targets on a moving calibration object.     

利用外部DEM辅助山区SAR立体像对匹配及地形制图

SAR立体像对的匹配是利用雷达摄影测量技术提取地形高程信息的关键,匹配精度将直接影响结果 DEM的高程精度。针对山区SAR立体像对匹配过程中同名点选取困难的问题,引入外部粗分辨率DEM作为辅助数据,将该DEM高程转换为视差,为匹配提供初值,同时采用金字塔匹配策略,不仅可以缩小搜索范围,提高搜索效率,而且能够减少粗差的产生。试验结果表明,采用外部DEM辅助之后,匹配粗差点数量相对于传统的雷达摄影测量处理结果明显减少,从而有效地提高了高程信息提取重建的精度。     

地磁匹配中的地磁日变效应

针对目前地磁匹配研究中往往忽略地磁日变的影响,文中分别基于IGRF11模型和MAD匹配算法探讨了地磁匹配中的地磁日变效应.基于IGRF11模型的定性分析表明,地磁日变效应显著,即使在地磁变化较为平缓的区域,地磁日变仍给匹配定位带来较大影响.分别利用地磁平静时期广州、兰州、北京十三陵3个地磁台站分均值数据,基于MAD匹配算法定量分析了地磁日变效应.结果表明,匹配定位误差呈现出类似于日变形态的变化特征,且纬度效应显著,广州台站纬度方向上的最大误差达0.189°,经度误差达0.492°.     

北京市细颗粒物时空分布及与呼吸系统疾病相关分析

细颗粒物（PM2.5）即粒径小于2.5μm的可吸入颗粒物[1],是当今中国城市大气污染的首要污染物。本研究以北京市为例,选取北京市2010年至2012年三年内采暖期与非采暖期两个不同时期的细颗粒物（PM0.3,PM0.5,PM1）实测数据,及同时期北京市患呼吸系统疾病人数数据,运用地统计的空间分析方法,对获取数据进行空间化及插值研究。通过偏相关分析法对北京市细颗粒物浓度与患呼吸系统疾病人数数据进行相关分析。得出以下主要结论：①细颗粒物的空间变化明显,2010年、2011年及2012年细颗粒物浓度整体呈上升趋势,2012年三种粒径细颗粒物浓度整体高于2010年与2011年。②不同粒径的细颗粒物,对呼吸疾病的影响程度不同：在0.3μm,0.5μm与1μm三种粒径的细颗粒物中,PM1对呼吸系统疾病影响最大,偏相关系数达到0.785。     

3维最小二乘表面匹配泛型数学模型及在机载LiDAR条带平差中的应用

以3维表面间共轭点欧氏距离之和最小为理论基础,提出一种泛型3维表面匹配数学模型,并推导其最小二乘平差理论模型,利用该模型进行机载LiDAR点云条带平差。针对真实机载LiDAR点云数据进行条带平差对比实验,结果表明本文所提出的表面匹配模型,不仅能准确估计出相邻重叠3维表面间的正形变换参数,较好地解决机载LiDAR点云条带间配准问题,而且能同时适用于多种同名点对应准则,是一种泛型的配准模型。     

Automatic change detection for road networks from images based on GIS

Up to now, detailed strategies and algorithms of automatic change detection for road networks based on GIS have not been discussed. This paper discusses two different strategies of automatic change detection for images with low resolution and high resolution using old GIS data, and presents a buffer detection and tracing algorithm for detecting road from low-resolution images and a new profile tracing algorithm for detecting road from high-resolution images. For feature-level change detection (FL-CD), a so-called buffer detection algorithm is proposed to detect changes of features. Some ideas and algorithms of using GIS prior information and some context information such as substructures of road in high-resolution images to assist road detection and extraction are described in detail.     

Spectral identification of materials by reflectance spectral library search

Spectral library search is emerging as a viable approach for material identification and mapping by reusing spectral knowledge gained from hyperspectral remote sensing across space and time. The potential of retrieving meaningful spectral material identifications in the presence of reflectance of spectra of various material types and with various similarity metrics has been assessed in this study. Test reflectance spectra of various vegetation, minerals, soils and urban material types are identified by searching through the composite reflectance spectral library obtained by combining various institutional reflectance spectral libraries. The accuracy of material identifications under various conditions: (i) in the presence of identical, similar and dissimilar spectra; (ii) in the presence of only identical and dissimilar spectra; and (iii) in the presence of only dissimilar spectra has been assessed with several similarity metrics. Results indicate the possibility of obtaining 100% accurate material identifications by library search if the spectral library contains identical spectra. However, the presence of a large number of similar spectra, despite the presence of identical spectra, is found to increase false positives, thereby reducing the accuracy of retrievals to 82% at best. Further, the accuracy of material identifications in the presence of similar spectra is similarity metric-dependent and varied from about 52% (obtained from Binary Encoding) to 82% (obtained from Normalized Spectral Similarity Score). Overall, results support the possibility of using independent reflectance spectral libraries for material identification while calling for robust spectral similarity metrics.