一种融合预测过采样的运动目标检测算法

为了改善运动目标检测的精度,提出了一种融合了预测过采样的运动目标检测新方法.首先,基于二维傅里叶变换预测当前帧的目标形状并计算形状相似度;然后,从历史检测结果中选择一定数量的参考帧,使用光流法跟踪目标像素点在参考帧与当前帧之间的运动轨迹,并以像素点轨迹为参考在采样区间执行稠密过采样;最后,基于过采样样本构造前景模型,并在图分割框架内联合使用前景背景模型实现目标检测.在公共数据与自采数据集上对所提方法进行了实验验证,结果表明,相对于经典的运动目标检测算法,所提方法能够有效提高检测精度.     

Motion detection using block based bi-directional optical flow method

Detecting moving objects from video frame sequences has a lot of useful applications in computer vision. This proposed method of moving object detection first estimates the bi-directional optical flow fields between (i) the current frame and the previous frame and between (ii) the current frame and the next frame. The bi-directional optical flow field is then subjected to normalization and enhancement. Each normalized and enhanced optical flow field is then divided into non-overlapping blocks. The moving objects are finally detected in the form of binary blobs by examining the histogram based thresholded values of such optical flow field of each block as well as the optical flow field of the candidate flow value. Our technique has been conceptualized, implemented and tested on real video data sets with complex background environment. The experimental results and quantitative evaluation establish that our technique achieves effective and efficient results than other existing methods.     

基于帧差法的运动车辆阴影去除算法

在视频交通车辆目标检测中,阴影问题是影响其检测准确性的关键问题之一.为了解决这个问题,提出了一种结合单模高斯模型和帧差法的运动目标阴影去除方法.首先通过单模高斯模型背景建模获取前景包括阴影在内的目标图像,再结合帧差法去除阴影.实验结果证明,该方法得到的车辆目标比较完整,并较好地去除了运动车辆阴影.     

基于背景差分和混合帧差的运动目标检测

针对利用核密度估计建立背景模型时计算量大,运动目标和外界环境容易发生变化,提出一种基于改进的核密度估计背景差分法和改进的混合帧差法相结合的运动目标检测方法。该方法在背景建模时,先对背景差分后的图像进行分块和分类,并简化了核密度估计的核函数,对前景块中的像素进行核密度估计,减少了计算量。在混合帧差法中增加了动态阈值,提高了对光线变化的适应性。实验结果表明该方法能够完整地提取出运动目标,提高了目标检测的准确率。     

Moving cast shadow detection using online sub-scene shadow modeling and object inner-edges analysis

In this paper, we propose an adaptive and accurate moving cast shadow detection method employing online sub-scene shadow modeling and object inner-edges analysis for applications of static-camera video surveillance. To describe shadow appearance more accurately, the proposed method builds adaptive online shadow models for sub-scenes with different conditions of irradiance and reflectance. The online shadow models are learned by utilizing Gaussian functions to fit the significant peaks of accumulating histograms, which are calculated from Hue, Saturation and Intensity (HSI) difference of moving objects between background and foreground. Additionally, object inner-edges analysis is adopted to reject camouflages, which are misclassified foreground regions that are highly similar to shadows. Finally, the main shadow regions are expanded to recycle the misclassified shadow pixels based on local color constancy. The proposed algorithm can adaptively handle the shadow appearance changes and camouflages without prior information about illuminations and scenarios. Experimental results demonstrate that the proposed method outperforms state-of-the-art methods.     

Traffic flow detection and statistics via improved optical flow and connected region analysis

Moving vehicle detection plays an important role in intelligent transportation systems. One of the common methods used in moving vehicle detection is optical flow. However, conventional Horn–Schunck optical flow consumes too much time when calculating dense optical flows so that it cannot meet the real-time requirements. This paper proposes a novel improved Horn–Schunck optical flow algorithm based on inter-frame differential method. In our algorithm, optical flow field distribution is only calculated for pixels with larger gray values in the difference image, while for other pixels we applied the iterative smooth. The number of vehicles in the videos of traffic conditions is counted by setting the virtual loop and detecting optical flow information. To extract the moving vehicle as accurately as possible, we also propose a method to obtain moving vehicle minimum bounding rectangle based on the connected region analysis. Finally, we compare the improved optical flow with other four optical flow algorithms in moving vehicle extraction and vehicle flow detection, from which our method gives a much more accurate result.     

基于改进高斯混合模型的运动图像目标检测算法

运动图像目标检测指的是从序列图像中将变化的目标从背景中分离出来,高斯混合模型可以对视频序列图像的前景和背景进行分类,再利用背景减除实现运动目标的检测。提出一种基于改进高斯混合模型的优化背景建模方法,该方法首先利用3×3模板对序列图像帧中的像素进行类似卷积的均值计算,然后利用相邻均值的差提取均差因子自适应更新图像的均值。在此基础上,设计了自适应学习率和学习速率,利用改进高斯混合模型实现序列图像的背景建模。改进模型不仅能有效减少数据计算量,同时可以降低在相似区域像素计算的时长,大大加快背景建模速度。实验结果表明,改进模型在目标检测、算法执行速率等性能指标上都有更好的表现,能满足实时检测要求。     

基于DSP的无背景模型车流量检测

针对车流量检测中遇到光照变化、树阴、树枝摇动等一系列问题,在运动物体法,背景建模法和时间差分法的基础上,提出了一种基于DSP的无背景模型的新型车流量检测方法。笔者依次使用基于块的帧差法、双重前景融合法、基于纹理对象分割法、假前景滤波法对车流量进行检测。经实验验证,采用无背景模型算法能成功有效地检测车流量,检测准确率达88%,提高了车流量检测的精度。     

Detecting moving object from dynamic background video sequences via simulating heat conduction

Moving object detection is one of the essential tasks for surveillance video analysis. The dynamic background often composed by waving trees, rippling water or fountains, etc. in nature scene greatly interferes with the detection of moving objects in the form of noise. In this paper, a method simulating heat conduction is proposed to extract moving objects from dynamic background video sequences. Based on the visual background extractor (ViBe) with an adaptable distance threshold, we design a temperature field relying on the generated mask image to distinguish between the moving objects and the noise caused by dynamic background. In temperature field, a brighter pixel is associated with more energy. It will transfer a certain amount of energy to its neighboring darker pixels. Through multiple steps of energy transfer the noise regions loss more energy so that they become darker than the detected moving objects. After heat conduction, K-Means algorithm with the customized initial clustering centers is utilized to separate the moving objects from background. We test our method on many videos with dynamic background from public datasets. The results show that the proposed method is feasible and effective for moving object detection from dynamic background sequences.     

基于深度学习的ViSAR多运动目标检测

视频合成孔径雷达(ViSAR)在地面动目标检测和感兴趣区域(ROI)的动态监测方面具有巨大的潜力。对地面运动目标的检测与跟踪一直是ViSAR的研究热点。针对现有基于深度学习的ViSAR动目标检测方法存在的依赖预训练模型,模型迁移难等问题,本文提出了一种基于深度学习与多目标跟踪(MOT)算法的ViSAR动目标阴影检测方法。该方法首先设计了一种从零开始深度学习的网络模型,实现动目标阴影的单帧检测。为了提高检测性能的鲁棒性,采用了基于卡尔曼滤波和逐帧数据关联的多目标跟踪算法跟踪动目标。实测数据处理结果表明该方法具有良好的检测性能。     

基于相关配准的帧间差分算法

针对帧间差分法在摄像头运动时受动态背景严重干扰的问题,提出了一种基于图像配准的运动目标检测算法。首先将中值滤波后的连续两帧图像配准,配准时先在前一帧图像中选取背景,即背景图像,用区域相关法将后一帧图像与背景图像配准;接着将配准后的2帧图像差分得到帧间差分图像,即帧差图像,再用数学形态学的开运算去掉帧差图像中的一些细小噪声;最后将连续两帧去噪后的帧差图像逻辑与运算,得到运动目标检测结果。实验结果表明,在摄像头运动时的动态背景下,该算法有效地抑制了动态背景的干扰,准确地检测出了运动目标的边界,提高了运动目标检测在动态背景下的应用价值。     

A self-organizing approach to background subtraction for visual surveillance applications.

Detection of moving objects in video streams is the first relevant step of information extraction in many computer vision applications. Aside from the intrinsic usefulness of being able to segment video streams into moving and background components, detecting moving objects provides a focus of attention for recognition, classification, and activity analysis, making these later steps more efficient. We propose an approach based on self organization through artificial neural networks, widely applied in human image processing systems and more generally in cognitive science. The proposed approach can handle scenes containing moving backgrounds, gradual illumination variations and camouflage, has no bootstrapping limitations, can include into the background model shadows cast by moving objects, and achieves robust detection for different types of videos taken with stationary cameras. We compare our method with other modeling techniques and report experimental results, both in terms of detection accuracy and in terms of processing speed, for color video sequences that represent typical situations critical for video surveillance systems.     

基于改进的混合高斯模型的运动目标检测方法

为了改善混合高斯模型在光照突变时容易产生大量误检的缺陷,采用了一种高斯模型与均值法相结合并为前景像素建立计数器的方法。在建立背景模型时,运用多帧图像求平均值的方法初始化混合高斯模型的背景;为每帧图像的前景像素数建立计数器,并以此消除被误判为前景的区域;对检测出的前景区运用数学形态学处理,得到图像真正的前景区域。结果表明,该算法不仅克服了初始背景中的干扰,而且消除了光照突变时的误检,提高了运动目标的检测率。     

无人机视频图像运动目标检测算法综述

运动目标检测是实现目标跟踪、交通监控、行为分析等任务的基础。但在无人机获取的视频图像中,无人机运动、旋翼震动或外界风力等客观因素使图像出现较为明显的背景、光照等变化,会对运动目标的检测产生影响。因此,如何降低干扰、提高检测精度,让无人机在运动目标检测领域发挥作用在信息时代具有相当重要的意义。无人机视频图像的运动目标检测相比传统运动目标检测,检测思路基本一致,但干扰因素众多。本文以此为切入点,分类综述了适用于无人机视频图像运动目标检测的算法及其改进,主要包括运动估计算法、帧间差法、背景建模法、光流法等传统算法和近年出现的新型算法;通过对无人机运动状态的划分探讨比较了上述方法的优缺点及适用场景。帧间差法更适合处理无人机悬停状态的数据,背景建模法、光流法及新型算法对无人机悬停及巡航状态的数据均可处理;上述算法均不能很好解决光照变化造成误检、漏检现象。所以处理无人机视频数据时,要根据其运动信息及数据特点选择合适的算法,才能获得好的检测结果。     

一种基于视频的道路行人检测方法

提出了一种基于交通视频的道路行人检测方法。首先,采用具有自适应背景更新的背景差法提取运动目标。其次,利用行人的轮廓特征和行人在图像上的像素高度与实际距离的线性变化关系特征进一步分割行人目标,并依据行人位置特征对其做多帧匹配跟踪。最后,结合行人速度特征,实现行人目标检测。实验结果表明,该方法能准确地检测交通场景中出现的行人目标,有效地解决运动车辆的遮挡和光照等对行人目标检测的影响,具有良好的实时性和稳健性。     

HOS运动目标分割算法在视频监控中的应用

为了提高视频监控中运动目标分割的速度和准确度,研究并实现了一种基于高阶统计量HOS(HigherOrder Statistics)的分割算法.首先根据HOS假设检验处理帧差图,判定像素点是否属于运动区域,阈值通过灰度共生矩阵获得,考虑了背景纹理的慢变化.然后,用矩形框聚类法大致确定运动目标的范围,在该范围内使用形态运算法和首尾扫描法去除空洞.最后,使用模板相与法获得帧图像的运动目标模板,从原图像中分割运动区域.算法采用了由粗到精的分析策略,实验表明,是一种快速稳健的算法.     

特征图知识蒸馏引导的轻量化任意方向SAR舰船目标检测器

基于有向边界框的合成孔径雷达(SAR)舰船目标检测器能输出精准的边界框,但仍存在模型计算复杂度高、推理速度慢、存储消耗大等问题,导致其难以在星载平台上部署。基于此该文提出了结合特征图和检测头分支知识蒸馏的无锚框轻量化旋转检测方法。首先,结合目标的长宽比和方向角信息提出改进高斯核,使生成的热度图能更好地刻画目标形状。然后在检测器预测头部引入前景区域增强分支,使网络更关注前景特征且抑制背景杂波的干扰。在训练轻量化网络时,将像素点间的相似度构建为热度图蒸馏知识。为解决特征蒸馏中正负样本不平衡问题,将前景注意力区域作为掩模引导网络蒸馏与目标相关的特征。另外,该文提出全局语义模块对像素进行上下文信息建模,能够结合背景知识加强目标精确表征。基于HRSID数据集的实验结果表明所提方法在模型参数仅有9.07 M的轻量化条件下,mAP能达到80.71%,且检测帧率满足实时应用需求。      

基于深度帧差卷积神经网络的运动目标检测方法研究

复杂场景中的运动目标检测是计算机视觉领域的重要问题,其检测准确度仍然是一大挑战.本文提出并设计了一种用于复杂场景中运动目标检测的深度帧差卷积神经网络（Deep Difference Convolutional Neural Network,DFDCNN）.DFDCNN由DifferenceNet和AppearanceNet组成,不需要后处理就可以预测分割前景像素.DifferenceNet具有孪生Encoder-Decoder结构,用于学习两个连续帧之间的变化,从输入（t帧和t+1帧）中获取时序信息;AppearanceNet用于从输入（t帧）中提取空间信息,并与时序信息融合;同时,通过多尺度特征图融合和逐步上采样来保留多尺度空间信息,以提高网络对小目标的敏感性.在公开标准数据集CDnet2014和I2R上的实验结果表明：DFDCNN不仅在动态背景、光照变化和阴影存在的复杂场景中具有更好的检测性能,而且在小目标存在的场景中也具有较好的检测效果.     

基于场景感知的运动目标检测方法

背景减除法是一种主要的运动目标检测框架,但在复杂环境中构建一种初始模型建立周期短、可靠性高、鲁棒性好的模型仍是一大难题.本文从场景感知的角度出发,在背景减除框架的基础上提出一种目标检测方法.该方法根据前两帧中稳定的结构信息感知背景中潜在的前景区域,在第二帧建立初始模型时利用最近邻域背景像素点代替可能的前景像素点,提高了初始模型可靠性;结合颜色信息和二进制特征提出了像素点二级分类判决机制,并通过感知像素点邻域内的纹理复杂度自适应调整局部判决阈值和更新频率;在模型更新阶段提出处理误判的反馈机制.在公开视频序列上同几种流行检测算法的实验对比结果证明了本文算法的有效性和优越性.