共查询到20条相似文献,搜索用时 0 毫秒
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自由拍摄视点下的可见外壳生成算法 总被引:2,自引:0,他引:2
给出了一种使用手持相机拍摄的多幅图像构造可见外壳的方法,该方法无需对相机运动方式作任何限定,而是利用多幅图像上的对应特征点求出每一幅图像的拍摄方位,因而可以非常灵活地获取某些较大规模的室外场景的几何模型.实验结果表明,利用该方法生成的可见外壳模型准确真实,能够满足虚拟现实等应用中的要求. 相似文献
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在动态场景图像序列中检测运动目标时,如何消除因摄影机运动带来的图像帧间全局运动的影响,以便分割图像中的静止背景和运动物体,是一个必须解决的难题。针对复杂背景下动态场景图像序列的特性,给出了一种新的基于场景图像参考点3D位置恢复的图像背景判别方法和运动目标检测方法。首先,介绍了图像序列的层次化运动模型以及基于它的运动分割方法;然后,利用估计出的投影矩阵计算序列图像中各运动层的参考点3D位置,根据同一景物在不同帧中参考点3D位置恢复值的变化特性,来判别静止背景对应的运动层和运动目标对应的运动层,从而分割出图像中的静止背景和运动目标;最后,给出了动态场景图像序列中运动目标检测的详细算法。实验结果表明,新算法较好地解决了在具有多组帧间全局运动参数的动态场景序列图像中检测运动目标的问题,较大地提高了运动目标跟踪算法的有效性和鲁棒性。 相似文献
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Self-Calibration of a Moving Camera from Point Correspondences and Fundamental Matrices 总被引:23,自引:1,他引:23
We address the problem of estimating three-dimensional motion, and structure from motion with an uncalibrated moving camera. We show that point correspondences between three images, and the fundamental matrices computed from these point correspondences, are sufficient to recover the internal orientation of the camera (its calibration), the motion parameters, and to compute coherent perspective projection matrices which enable us to reconstruct 3-D structure up to a similarity. In contrast with other methods, no calibration object with a known 3-D shape is needed, and no limitations are put upon the unknown motions to be performed or the parameters to be recovered, as long as they define a projective camera.The theory of the method, which is based on the constraint that the observed points are part of a static scene, thus allowing us to link the intrinsic parameters and the fundamental matrix via the absolute conic, is first detailed. Several algorithms are then presented, and their performances compared by means of extensive simulations and illustrated by several experiments with real images. 相似文献
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摄像机运动情况下的运动对象检测 总被引:2,自引:0,他引:2
在监控应用中,由于场景是已知的,因此可以使用背景减去法检测运动对象.当摄像机进行扫描和倾斜运动时,需要使用多个图像帧才能完整地表示监控场景.如何组织和索引这些背景帧属于摄像机跟踪问题.提出一种无需摄像机标定的背景帧索引和访问方法.这一方法需要使用图像配准技术估计图像初始运动参数.提出一种屏蔽外点的图像配准算法,综合利用线性回归和稳健回归快速估计初始运动参数.为了快速计算连续帧之间的运动参数,提出一种基于四参数模型的优化算法.利用非参数背景维护模型抑制虚假运动象素.室内和户外实验结果表明本文方法是有效的. 相似文献
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动态图像序列中的运动目标检测 总被引:7,自引:4,他引:7
根据动态图像序列中背景因成像过程中各种因素而产生变化所存在的复杂性,提出了自适应的前景目标检测方法。首先,建立图像每一像素点的高斯分布模型,并根据序列中的当前帧及历史帧信息自适应地调整模型的参数。然后,结合图像帧间的差分信息以及灰度分布的先验概率等因素将图像从空间域映射至统计域。最后,在统计域中对前景目标进行鲁棒分割。实验的结果反映了该方法的有效性。 相似文献
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Juliang Shao 《International Journal of Computer Vision》2002,47(1-3):171-180
The emergence of a new generation of 3D auto stereoscopic displays is driving the requirement for multi-baseline images. The dominant form of this display technology requires multiple views of the same scene, captured at a single instance in time along a common baseline in order to project stereoscopic images to the viewer. The direct acquisition of multiple views (typically 8 or 16 for the current generation of such displays) is problematic due to the difficulty of configuring, calibrating and controlling multiple cameras simultaneously.This paper describes a technique that alleviates these problems by generating the required views from binocular images. Considering each stereo pair in isolation leads to inconsistency across image sequences. By incorporating a motion-tracking algorithm this problem is significantly reduced. In this paper we describe a novel approach to stereo matching of image sequences for the purpose of generating multiple virtual cameraviews. Results of extensive tests on stereo image sequences will be documented indicating that this approach is promising both in terms of the speed of execution and the quality of the results produced. 相似文献
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序列图像中运动目标的分割定位 总被引:9,自引:1,他引:8
针对序列图像中运动目标的分割定位,给出了在复杂环境下一种快速识别运动目标、有效去除背景噪声及运动目标准确定位的方法。该方法主要由运动目标检测和运动目标定位分割两部分组成:对运动目标检测采用简单差分方法提取运动目标,快速中值滤波与数学形态学方法结合去除噪声;对运动目标定位提出了一种改进的区域生长分割算法RGSA(RegionGrowingSegmentationAlgorithm)定位目标,并求出目标重心。实验结果表明,该方法正确有效,结果令人满意。 相似文献
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结合计算机视觉技术和CCD测量原理。给出了一种运动目标姿态参数的测量方法,并推导了目标姿态测量的数学模型。对可能存在的误差源进行了分析,并提出了解决方法。该方法通过三个与CCD相匹配的标定点测量,采用四元法描述姿态,使得系统结构简单、速度快;仿真结果表明,系统角测量精度可达到1’,系统可以广泛应用于运动目标姿态的近距离测量。 相似文献
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摄像机的运动使得复杂背景下动目标的检测复杂化。为了应对动态变化的背景,本文提出基于SIFT特征匹配和运动历史图的目标检测算法。首先用SIFT算法提取特征点,采用RANSAC方法求得仿射变换模型参数并实现图像的全局运动补偿,最后利用运动历史图的方法检测出动目标。SIFT特征点匹配的准确性和RANSAC方法去除异常点的有效性使得仿射变换模型参数计算准确,运动历史图则给出了动目标清晰的轮廓,并指明了动目标的运动方向。与Ninad Thakoor实验结果对比说明:该算法能够准确地检测出动目标,并且显示了动目标的运动方向。 相似文献
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Björn Ommer Theodor Mader Joachim M. Buhmann 《International Journal of Computer Vision》2009,83(1):57-71
Category-level object recognition, segmentation, and tracking in videos becomes highly challenging when applied to sequences
from a hand-held camera that features extensive motion and zooming. An additional challenge is then to develop a fully automatic
video analysis system that works without manual initialization of a tracker or other human intervention, both during training
and during recognition, despite background clutter and other distracting objects. Moreover, our working hypothesis states
that category-level recognition is possible based only on an erratic, flickering pattern of interest point locations without
extracting additional features. Compositions of these points are then tracked individually by estimating a parametric motion
model. Groups of compositions segment a video frame into the various objects that are present and into background clutter.
Objects can then be recognized and tracked based on the motion of their compositions and on the shape they form. Finally,
the combination of this flow-based representation with an appearance-based one is investigated. Besides evaluating the approach
on a challenging video categorization database with significant camera motion and clutter, we also demonstrate that it generalizes
to action recognition in a natural way.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.
This work was supported in part by the Swiss national science foundation under contract no. 200021-107636. 相似文献
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提出了一种自动的运动对象分割算法,利用浮点图像的轮廓及其颜色特征将第一帧图像进行区域分割,然后根据帧间运动信息构造出前景和背景图像,最后以前景和背景图像作为参考,对同一场景中所有视频帧进行快速可靠的分割。 相似文献
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《Real》1998,4(1):3-20
This article is concerned with the design and implementation of a system for real-time monocular tracking of a moving object using the two degrees of freedom of a camera platform. Figure-ground segregation is based on motion without making anya prioriassumptions about the object form. Using only the first spatiotemporal image derivatives, substraction of the normal optical flow induced by camera motion yields the object image motion. Closed-loop control is achieved by combining a stationary Kalman estimator with an optimal Linear Quadratic Regulator. The implementation on a pipeline architecture enables a servo rate of 25 Hz. We study the effects of time-recursive filtering and fixed-point arithmetic in image processing and we test the performance of the control algorithm on controlled motion of objects. 相似文献
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基于单平面模板的摄像机定标研究 总被引:2,自引:0,他引:2
提出了一种摄像机定标方法,只需要摄像机从不同方向拍摄平面模板的多幅图像,摄像机与平面模板间可以自由地移动,运动的参数无需已知。对于每个视点获得图像,提取图像上的网格角点;平面模板与图像间的网格角点对应关系,确定了单应性矩阵;对每幅图像,就可确定一个单应性矩阵,这样就能够进行摄像机定标。该算法先有一个线性解法,然后基于极大似然准则对线性结果进行非线性优化求精。该方法同时也考虑了镜头畸变的影响。实验结果表明该算法简单易用。 相似文献
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Learned Models for Estimation of Rigid and Articulated Human Motion from Stationary or Moving Camera
We propose an approach for modeling, measurement and tracking of rigid and articulated motion as viewed from a stationary or moving camera. We first propose an approach for learning temporal-flow models from exemplar image sequences. The temporal-flow models are represented as a set of orthogonal temporal-flow bases that are learned using principal component analysis of instantaneous flow measurements. Spatial constraints on the temporal-flow are then incorporated to model the movement of regions of rigid or articulated objects. These spatio-temporal flow models are subsequently used as the basis for simultaneous measurement and tracking of brightness motion in image sequences. Then we address the problem of estimating composite independent object and camera image motions. We employ the spatio-temporal flow models learned through observing typical movements of the object from a stationary camera to decompose image motion into independent object and camera motions. The performance of the algorithms is demonstrated on several long image sequences of rigid and articulated bodies in motion. 相似文献
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本研究实现了从0/1矩阵的横向、纵向和还原出矩阵,这个方法在三维重建中有广泛的用途。本研究成功地从两张相互垂直的人体腿部模型的投影还原出三维模型,并且误差非常小,从而证明了此方法在三维重建中非常有效。 相似文献
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: Visuo-spatial neglect is recognised as a major barrier to recovery following a stroke or head injury. A standard clinical
assessment technique to assess the condition is a pencil-and-paper based cancellation task. Traditional static analysis of this task involves counting the number of targets correctly cancelled on the test sheet. Using a computer-based
test capture system, this paper presents the novel application of using a series of standard pattern recognition techniques
to examine the diagnostic capability of a number of dynamic features relating to the sequence in which the targets were cancelled. While none of the individual dynamic features is as
sensitive to neglect as the conventional static analysis, a series of standard multi-dimensional feature analysis techniques
are shown to improve the classification accuracy of the dynamic properties of task execution, and hence the sensitivity to
the detection of neglect and the validity of this novel application. Combining the outcome of the dynamic sequence-based features
with the conventional static analysis further improves the overall sensitivity of the two cancellation tasks included in this
study. The algorithmic nature of the methodology for feature extraction objectively and consistently assesses patients, thereby
improving the repeatability of the task.
Received: 16 April 2001, Received in revised form: 28 May 2001, Accepted: 31 May 2001 相似文献