共查询到19条相似文献,搜索用时 187 毫秒
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传统的分析景象匹配可靠性是通过研究匹配信噪比、独立像元数、参与匹配的像元数来进行的,但对于雷达景象由于其特殊的图像特性,传统的方法往往得不出正确的可靠性分析结果。从搜索图的对比度来研究景象匹配可靠性问题,根据匹配过程中的特点,第一次从理论上推导出了对比度和匹配可靠性的定量关系,通过大量实践表明,运用对比度来分析雷达景象匹配的可靠性是一种十分有效的方法。 相似文献
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从图像特性的角度,研究了匹配实时图对比度变化对雷达景象匹配可靠性的影响,并根据匹配过程中的特点,从理论上推导出了对比度和相关系数的定量关系,通过大量实践表明,提高实时图的对比度可以提高雷达景象匹配的可靠性,通过对比度来增强匹配可靠性是一种行之有效的方法. 相似文献
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针对侧视雷达/可见光图像匹配制导系统中由于雷达图像地形畸变引起的误匹配问题,提出了一种基于干涉合成孔径雷达(InSAR)的实时地形校正图像匹配算法。该算法以侧视雷达成像几何构象为基础,利用InSAR获取的实时地形数据对获取的SAR景象数据进行实时几何校正,生成无畸变的SAR景象数据,然后利用校正后的SAR景象数据与提前安装的可见光基准数据进行基于去均值归一化互相关模板的图像匹配。实验结果表明,通过实时地形校正,该景象匹配算法在复杂地形区域的匹配概率和匹配精度都大大优于传统SAR景象匹配算法,有效地提高了SAR图像匹配制导技术的适用性。 相似文献
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为了提高数字景象匹配的技术性能,将分形理论应用于景象匹配领域,提出了一种用于景象匹配的采用归一化方法改进的双毯覆盖算法,并阐述了数字景物图象分形维数的求解方法,同时采用粗匹配和精匹配两级匹配来改善匹配概率与实时图的亮度和对比度等因素有关,这对于进一步探索改善该算法的匹配性能,具有重要意义。 相似文献
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在无人驾驶飞行器的自主制导系统中,一般采用下视景像匹配制导技术对飞行器的具体位置进行精确自主定位。为了提高制导精度,减少误匹配,飞行前需要在基准图上进行航迹规划,就是在飞行区域中选择出一些匹配概率肓的匹配区。在选择过程中,匹配概率的计算尤为重要,用相关匹配定义计算虽然准确但耗时巨大。文章提出了一种基于Gabor小波特征的匹配概率预测方法。实验表明,该方法能较快地预测出匹配概率,精度也较高。 相似文献
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基于景象匹配制导的飞行器飞行前需要进行航迹规划,就是在飞行区域中选择出一些匹配概率高的匹配区,作为相关匹配制导的基准,由此提出了估计匹配区匹配概率的问题.本文模拟飞行中匹配定位的过程定义了匹配概率,并提出了基准图的三个特征参数,最后通过Fisher线性分类器,实现了用特征参数估计匹配概率的目标,并进行了实验验证. 相似文献
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具有旋转不变性的模板匹配算法在工业制造上具有广泛的应用。为解决传统的模板匹配方法在目标旋转、匹配速度上的问题,提出一种基于局部方差和后验概率分类的模板匹配方法。为减少计算量,在匹配中通过局部方差过滤掉部分候选窗口,并在后验概率分类模块中通过对比不同区域稳定特征点对的灰度来计算窗口相关性。使用后验概率分类计算窗口相关度能在预处理过程实现旋转不变性,并保证准确率在95%以上。实验结果表明,该算法在80万像素级的任意角度匹配图像上选择合适的窗口移动步长后,可将匹配时间减少到10 ms以内,相较于现有算法速度更快。 相似文献
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针对范例匹配中的冲突问题,提出了基于引入概率的一种范例匹配新方法,并给出了概率确定、引入以及最终相似度计算的完整理论。首先采用阀值判断过滤范例;然后在模型中引入概率,并通过调整影响因子来改变引入概率对最终相似度的影响;最后计算比较最终相似度得出最优相似范例。实例证明,该方法提高了范例匹配的时效性和准确性。 相似文献
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《IEEE transactions on pattern analysis and machine intelligence》2003,25(3):301-315
We address the question of how to characterize the outliers that may appear when matching two views of the same scene. The match is performed by comparing the difference of the two views at a pixel level aiming at a better registration of the images. When using digital photographs as input, we notice that an outlier is often a region that has been occluded, an object that suddenly appears in one of the images, or a region that undergoes an unexpected motion. By assuming that the error in pixel intensity generated by the outlier is similar to an error generated by comparing two random regions in the scene, we can build a model for the outliers based on the content of the two views. We illustrate our model by solving a pose estimation problem: the goal is to compute the camera motion between two views. The matching is expressed as a mixture of inliers versus outliers, and defines a function to minimize for improving the pose estimation. Our model has two benefits: First, it delivers a probability for each pixel to belong to the outliers. Second, our tests show that the method is substantially more robust than traditional robust estimators (M-estimators) used in image stitching applications, with only a slightly higher computational complexity. 相似文献
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K. Nackaerts Corresponding author K. Vaesen I. Lizarraga B. Muys P. Coppin 《International journal of remote sensing》2013,34(14):2713-2723
Traditionally, the validation of a classified multispectral image only quantifies its correspondence to ground reference data containing thematic information generalized at the stand level, with stands represented as vector polygons. Little is known of the accuracy of such classifications at a scale below the stand. This study presents a methodology to assess classification accuracy at pixel level, i.e. sub-polygon, where the classification procedure is embedded in a change detection environment. A new type of reference data (Metatruth Image) was generated based on the integration of the outputs of various independent change detection procedures. The integration consisted of calculating for each pixel a probability distribution or pixel purity index for each change class by independent change detection procedures, defined by the number of times the pixel has been classified as a certain change class. First, the relationship between purity and accuracy was successfully validated. Next, the Metatruth Image was created based on ‘high purity pixels’. Performing traditional accuracy assessment on the outputs of individual change detection procedures using the Metatruth Image as reference dataset, demonstrated that former outputs identified change events accurately at pixel level. As a consequence, traditional accuracy assessment at polygon level underestimates the true accuracy at pixel level of the change detection procedure in a systematic way with differences in kappa coefficients of agreement around 20%. 相似文献
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提出了一种基于分类的背景更新算法。对现有模板进行改进,提出一种生长模板来对差分图像中的目标点和噪声点进行检测。生长模板根据像素点局部特征自动选择生长方向,从而对目标点和噪声点进行判断。利用基于像素的背景更新策略,实现了目标遮挡区域的背景更新。实验证明了生长模板的有效性,该算法可以在复杂场景下实现背景更新。 相似文献
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主要论述了图像融合的基本知识,对多聚焦图像传统的基于空间频率的融合算法进行了改进。分别计算多聚集图像对应位置上每个像素所在窗口的空间频率,然后根据空间频率的大小对该位置像素进行处理,最后生成同一场景中所有物体都清晰的融合结果图像。通过仿真实验验证了算法的有效性,结果表明,该算法在多聚焦图像融合上要优于传统算法。 相似文献
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The problem of matching two images of the same scene, taken by different sensors under different viewing geometries, is a challenging problem in the field of image processing and pattern recognition. The scenes are usually transformed so drastically by the different viewing geometries and sensor characteristics that it is extremely difficult, if not impossible, to match the original images without the proper data processing. Geometric and intensity transformations must be performed to bring the matching elements and their intensity into a one-to-one correspondence. Objects of interest represented by subimages of one scene were located in the other using scene matching techniques with intensity difference and edge features as measurement features. Performance characteristics of the matches by these techniques are presented in terms of the probability of a match as a function of the probability of false fix. 相似文献
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A novel algorithm for vehicle average velocity detection through automatic and dynamic camera calibration based on dark channel in homogenous fog weather condition is presented in this paper. Camera fixed in the middle of the road should be calibrated in homogenous fog weather condition, and can be used in any weather condition. Unlike other researches in velocity calculation area, our traffic model only includes road plane and vehicles in motion. Painted lines in scene image are neglected because sometimes there are no traffic lanes, especially in un-structured traffic scene. Once calibrated, scene distance will be got and can be used to calculate vehicles average velocity. Three major steps are included in our algorithm. Firstly, current video frame is recognized to discriminate current weather condition based on area search method (ASM). If it is homogenous fog, average pixel value from top to bottom in the selected area will change in the form of edge spread function (ESF). Secondly, traffic road surface plane will be found by generating activity map created by calculating the expected value of the absolute intensity difference between two adjacent frames. Finally, scene transmission image is got by dark channel prior theory, camera’s intrinsic and extrinsic parameters are calculated based on the parameter calibration formula deduced from monocular model and scene transmission image. In this step, several key points with particular transmission value for generating necessary calculation equations on road surface are selected to calibrate the camera. Vehicles’ pixel coordinates are transformed to camera coordinates. Distance between vehicles and the camera will be calculated, and then average velocity for each vehicle is got. At the end of this paper, calibration results and vehicles velocity data for nine vehicles in different weather conditions are given. Comparison with other algorithms verifies the effectiveness of our algorithm. 相似文献
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Enderton E Sintorn E Shirley P Luebke D 《IEEE transactions on visualization and computer graphics》2011,17(8):1036-1047
Stochastic transparency provides a unified approach to order-independent transparency, antialiasing, and deep shadow maps. It augments screen-door transparency using a random sub-pixel stipple pattern, where each fragment of transparent geometry covers a random subset of pixel samples of size proportional to alpha. This results in correct alpha-blended colors on average, in a single render pass with fixed memory size and no sorting, but introduces noise. We reduce this noise by an alpha correction pass, and by an accumulation pass that uses a stochastic shadow map from the camera. At the pixel level, the algorithm does not branch and contains no read-modify-write loops, other than traditional z-buffer blend operations. This makes it an excellent match for modern massively parallel GPU hardware. Stochastic transparency is very simple to implement and supports all types of transparent geometry, able without coding for special cases to mix hair, smoke, foliage, windows, and transparent cloth in a single scene. 相似文献