一种基于多分辨率与模糊聚类技术的散焦图像分割算法

带有投射光栅的散焦图像的准确分割是3维物体复原的重要环节。为了更准确地进行散焦图像分割，基于所提取的带光栅散焦图像特征，提出了一种将多分辨率分析与模糊聚类技术融合实现图像分割的算法。该算法是利用多分辨率技术来建立面向像素特征向量的多级图像联系矩阵，并在图像低分辨率级进行基于模糊聚类的区域分割。实验证明，该技术不仅克服了直接分割的困难，而且提高了分割的正确率，因此表明，该算法是有效的。     

基于有偏场的光栅图像模糊聚类分割算法*

针对有偏场环境下带有光栅的散焦图像分割问题,提出了一种新的基于有偏场估计的模糊聚类分割算法。通过建立依赖于有偏场的模糊聚类目标函数,导出了基于灰度以及邻域灰度均值的聚类中心、模糊聚类函数以及有偏场估计的迭代算法;并在该算法生成的初始分割基础上,利用膨胀算子对分类结果进行细化。该方法较好地处理了传统模糊聚类对有偏场下光栅图像分割精度下降的问题。实验结果表明,基于有偏场的模糊聚类算法能有效分割光栅图像,其分割精度优于传统模糊聚类和阈值法。     

一种偏置场环境下的模糊聚类分割算法

针对偏置环境下图像分割问题,提出了一种基于偏置场估计的模糊聚类算法。通过建立依赖于偏置场的模糊聚类目标函数,提出了模糊聚类隶属函数和偏置场估计的迭代算法。该方法较好地处理了传统模糊聚类在偏置场存在的情况下图像分割精度下降问题。实验结果表明,该算法能有效分割具有偏置噪声的图像,其分割精度优于传统模糊聚类法。     

Robust camera pose and scene structure analysis for service robotics

Successful path planning and object manipulation in service robotics applications rely both on a good estimation of the robot’s position and orientation (pose) in the environment, as well as on a reliable understanding of the visualized scene. In this paper a robust real-time camera pose and a scene structure estimation system is proposed. First, the pose of the camera is estimated through the analysis of the so-called tracks. The tracks include key features from the imaged scene and geometric constraints which are used to solve the pose estimation problem. Second, based on the calculated pose of the camera, i.e. robot, the scene is analyzed via a robust depth segmentation and object classification approach. In order to reliably segment the object’s depth, a feedback control technique at an image processing level has been used with the purpose of improving the robustness of the robotic vision system with respect to external influences, such as cluttered scenes and variable illumination conditions. The control strategy detailed in this paper is based on the traditional open-loop mathematical model of the depth estimation process. In order to control a robotic system, the obtained visual information is classified into objects of interest and obstacles. The proposed scene analysis architecture is evaluated through experimental results within a robotic collision avoidance system.     

Granulation,rough entropy and spatiotemporal moving object detection

A new spatio-temporal segmentation approach for moving object(s) detection and tracking from a video sequence is described. Spatial segmentation is carried out using rough entropy maximization, where we use the quad-tree decomposition, resulting in unequal image granulation which is closer to natural granulation. A three point estimation based on Beta Distribution is formulated for background estimation during temporal segmentation. Reconstruction and tracking of the object in the target frame is performed after combining the two segmentation outputs using its color and shift information. The algorithm is more robust to noise and gradual illumination change, because their presence is less likely to affect both its spatial and temporal segments inside the search window. The proposed methods for spatial and temporal segmentation are seen to be superior to several related methods. The accuracy of reconstruction has been significantly high.     

偏置场下光栅图像的目标轮廓特征点检测方法

文章目标是解决有偏场环境下带有光栅图像的目标轮廓特征点检测问题。针对目标轮廓特征检测中存在的有偏光照环境和光栅模式,提出了一个两步解决方案。首先采用一种新的基于有偏场估计的图像模糊聚类迭代算法,对原灰度图像进行分割;接着,利用Harris特征检测器提取分割后目标图像的候选特征点,并在Harris特征检测算法中提出了基于特征响应函数直方图的罚值选择方法。实验结果表明,在光栅纹理和偏置场并存情况下,该文提出的方法优于传统Harris角检测器,解决了传统Harris角检测在该特定环境下所面临的精度下降问题。文章提出的算法可用于偏置场环境下光栅图像目标形状分析。     

Real-time focus range sensor

Structures of dynamic scenes can only be recovered using a real-time range sensor. Depth from defocus offers an effective solution to fast and dense range estimation. However, accurate depth estimation requires theoretical and practical solutions to a variety of problems including recovery of textureless surfaces, precise blur estimation, and magnification variations caused by defocusing. Both textured and textureless surfaces are recovered using an illumination pattern that is projected via the same optical path used to acquire images. The illumination pattern is optimized to maximize accuracy and spatial resolution in computed depth. The relative blurring in two images is computed using a narrow-band linear operator that is designed by considering all the optical, sensing, and computational elements of the depth from defocus system. Defocus invariant magnification is achieved by the use of an additional aperture in the imaging optics. A prototype focus range sensor has been developed that has a workspace of 1 cubic foot and produces up to 512×480 depth estimates at 30 Hz with an average RMS error of 0.2%. Several experimental results are included to demonstrate the performance of the sensor     

多模型协作的分块目标跟踪

为解决复杂场景下,基于整体表观模型的目标跟踪算法容易丢失目标的问题,提出一种多模型协作的分块目标跟踪算法.融合基于局部敏感直方图的产生式模型和基于超像素分割的判别式模型构建目标表观模型,提取局部敏感直方图的亮度不变特征来抵制光照变化的影响;引入目标模型的自适应分块划分策略以解决局部敏感直方图算法缺少有效遮挡处理机制的问题,提高目标的抗遮挡性;通过相对熵和均值聚类度量子块的局部差异置信度和目标背景置信度,建立双权值约束机制和子块异步更新策略,在粒子滤波框架下,选择置信度高的子块定位目标.实验结果表明,本文方法在复杂场景下具有良好的跟踪精度和稳定性.     

一种稳健的足球机器人目标识别算法

视觉系统是类人足球机器人获取环境信息的主要途径。在比赛中,受场地光照等比赛环境的影响,用传统的分割识别算法难以达到满意的效果。文中提出一种结合目标颜色和形状信息的识别算法。该算法在HSI空间执行基于颜色信息的快速阀值分割,获取目标像素,并且加入了自适应阀值更新,然后利用目标像素和目标形状信息执行优化边缘检测识别目标,最终获得目标在图像中准确的位置信息。实验证明：该算法能长时间在不同光照条件下稳定获取对象在图像中的位置信息,满足实时性的要求。     

Color segmentation robust to brightness variations by using B-spline curve modeling

Color segmentation takes a great attention because color is an effective and robust visual cue for characterizing an object from the others. However, color segmentation suffers from color variations incurred by irregular illumination changes. We propose a reliable color modeling approach in hue–saturation–intensity (HSI) color space while considering intensity information by adopting the B-spline curve fitting to make a mathematical model for statistical characteristics of a color with respect to intensity. It is based on the fact that color distribution of a single-colored object is not invariant with respect to brightness variations even in the HS (hue–saturation) plane. The statistical characteristics contain the mean and standard deviation of hue and saturation with respect to intensity. They are mathematically expressed as four bar graphs. In order to fit the bar graphs to continuous curves, we use B-spline curve fitting procedure. From several experimental results, we verify that the proposed algorithm is successfully applied to color segmentation under various illumination conditions.     

地物提取的多尺度特征遥感应用分析

通过空间尺度效应分析,阐述不同属性景观地物在同一分辨率或同一尺度影像中提取的不合理性。为获得精确的地表信息,提出多尺度遥感影像分析方法,解决不同地物在不同空间尺度影像数据中提取的难题。通过多种分辨率影像的多尺度影像信息提取的应用实践,分析地物提取中的多尺度特性、尺度与分辨率关系等。     

Object-based illumination classification

Estimation of scene illumination from a single image or an image sequence has been widely studied in computer vision. The approach presented in this paper, introduces two new issues: (1) illumination classification is performed rather than illumination estimation; (2) an object-based approach is used for illumination evaluation. Thus, pixels associated with an object are considered in the illumination estimation process using the object's spectral characteristics. Simulation and real image experiments, show that the object-based approach indeed improves performance over standard illumination classification.     

基于图像分解的光照估计算法

增强现实技术的目的在于将计算机生成的虚拟物体叠加到真实场景中。实现良好的虚实融合需要对场景光照进行估算,针对高光场景,利用场景中的不同反射光信息对场景进行有效的光照估计,首先通过基于像素聚类方法的图像分解对图像进行反射光的分解,得到漫反射图和镜面反射图,对漫反射图进行进一步的本征图像分解,得到反照率图和阴影图;之后结合分解结果和场景深度对输入图像的光照信息进行计算;最后使用全局光照模型对虚拟物体进行渲染,可以得到虚实场景高度融合的光照效果。     

The illumination-invariant recognition of 3D objects using localcolor invariants

Traditional approaches to three dimensional object recognition exploit the relationship between three dimensional object geometry and two dimensional image geometry. The capability of object recognition systems can be improved by also incorporating information about the color of object surfaces. Using physical models for image formation, the authors derive invariants of local color pixel distributions that are independent of viewpoint and the configuration, intensity, and spectral content of the scene illumination. These invariants capture information about the distribution of spectral reflectance which is intrinsic to a surface and thereby provide substantial discriminatory power for identifying a wide range of surfaces including many textured surfaces. These invariants can be computed efficiently from color image regions without requiring any form of segmentation. The authors have implemented an object recognition system that indexes into a database of models using the invariants and that uses associated geometric information for hypothesis verification and pose estimation. The approach to recognition is based on the computation of local invariants and is therefore relatively insensitive to occlusion. The authors present several examples demonstrating the system's ability to recognize model objects in cluttered scenes independent of object configuration and scene illumination. The discriminatory power of the invariants has been demonstrated by the system's ability to process a large set of regions over complex scenes without generating false hypotheses     

基于块运动矢量加权的Snakes模型及在序列图像分割中的应用

经典的Snakes模型具有开放的、统一的架构，在此基础上，为了分割复杂背景的序列图像，产生了各种改进的Snakes模型，但都存在着不足：计算量大、需要先验知识、易受光流计算精度影响等。针对这些缺点，提出了块运动矢量加权的Snakes模型，可以用于复杂背景序列图像的分割。这种模型以图像中的边缘信息为分割的最终依据，结合块运动估计的结果，增强了序列图像分割的鲁棒性。根据运动场估计的结果在该模型中所起的作用，提出了边缘优先的块运动估计算法，大大减少了计算量。用块运动矢量加权的Snakes模型分割复杂背景序列图像，取得了好的分割结果。     

Automatic segmentation of VHR images using type information of local structures acquired by mathematical morphology

The morphological profile (MP) and differential morphological profile (DMP) have been used extensively to acquire spatial information to be used in the segmentation of very high resolution (VHR) remotely sensed images. In most of the previous approaches, the maxima of the MP and DMP were investigated to estimate the best representative scale in the spatial domain for the pixel under consideration. Then, the object type (i.e. dark, bright or flat) was estimated based on the location of the maximum. Finally, the image segmentation was performed using the scale and type information as features. This approach usually causes over-segmentation. In this study, we also investigate the relevance of the DMP and the meaningful object types underlying the pixel of interest, however, instead of the maxima of the DMP, the type information is estimated using the whole DMP which is weighted by a weight function. Thus, the scale is not estimated directly but used indirectly in the estimation of the characteristic type for the object to which the pixel belongs. Then, the pixels are clustered based on their types only. The method has been applied to panchromatic high resolution QuickBird satellite images of the city of Ankara, Turkey. The results of the method were compared with previous studies and the proposed method seems to segment the images more precisely and semantically than the previous approaches.     

深度学习单目深度估计研究进展

单目深度估计是从单幅图像中获取场景深度信息的重要技术,在智能汽车和机器人定位等领域应用广泛,具有重要的研究价值。随着深度学习技术的发展,涌现出许多基于深度学习的单目深度估计研究,单目深度估计性能也取得了很大进展。本文按照单目深度估计模型采用的训练数据的类型,从3个方面综述了近年来基于深度学习的单目深度估计方法：基于单图像训练的模型、基于多图像训练的模型和基于辅助信息优化训练的单目深度估计模型。同时,本文在综述了单目深度估计研究常用数据集和性能指标基础上,对经典的单目深度估计模型进行了性能比较分析。以单幅图像作为训练数据的模型具有网络结构简单的特点,但泛化性能较差。采用多图像训练的深度估计网络有更强的泛化性,但网络的参数量大、网络收敛速度慢、训练耗时长。引入辅助信息的深度估计网络的深度估计精度得到了进一步提升,但辅助信息的引入会造成网络结构复杂、收敛速度慢等问题。单目深度估计研究还存在许多的难题和挑战。利用多图像输入中包含的潜在信息和特定领域的约束信息,来提高单目深度估计的性能,逐渐成为了单目深度估计研究的趋势。     

Neural network approach to background modeling for video object segmentation.

This paper presents a novel background modeling and subtraction approach for video object segmentation. A neural network (NN) architecture is proposed to form an unsupervised Bayesian classifier for this application domain. The constructed classifier efficiently handles the segmentation in natural-scene sequences with complex background motion and changes in illumination. The weights of the proposed NN serve as a model of the background and are temporally updated to reflect the observed statistics of background. The segmentation performance of the proposed NN is qualitatively and quantitatively examined and compared to two extant probabilistic object segmentation algorithms, based on a previously published test pool containing diverse surveillance-related sequences. The proposed algorithm is parallelized on a subpixel level and designed to enable efficient hardware implementation.     

采用统计推断的自动视频对象分割

在新一代MPEG－4视频编码标准中，为了支持面向对象编码和实现基于内容的应用，视频对象（VO）的自动分割成为关键技术之一，减背景法是视频对象自动分割的基本方法，但是不同的环境光照条件常常给视频对象的分割带来困难，提出一种基于统计推断的减背景法。该方法首先建立背景统计模型，然后对后续帧进行假设检验，从而分割出视频对象。文中算法采用HSV颜色空间，通过对背景统计模型中各颜色分量的有效分析和区别使用，能够很好地适应不同的环境光照条件。实验表明，文中算法能够在各种光照环境下自动地实现视频对象的准确分割。