检索结果-内蒙古大学图书馆

Direct computation of shape cues using scale-adapted spatial derivative operators

INTERNATIONAL JOURNAL OF computer vision 1996年第2期17卷 163-191页

作者： Garding, J Lindeberg, T Computational Vision and Active Perception Laboratory (CVAP) Department of Numerical Analysis and Computing Science KTH (Royal Institute of Technology) S-100 44 Stockholm Sweden

This paper addresses the problem of computing cues to the three-dimensional structure of surfaces in the world directly from the local structure of the brightness pattern of either a single monocular image or a binocular image pair. It is shown that starting from Gaussian derivatives of order up to two at a range of scales in scale-space, local estimates of (i) surface orientation from monocular texture foreshortening, (ii) surface orientation from monocular texture gradients, and (iii) surface orientation from the binocular disparity gradient can be computed without iteration or search, and by using essentially the same basic mechanism. The methodology is based on a multi-scale descriptor of image structure called the windowed second moment matrix, which is computed with adaptive selection of both scale levels and spatial positions. Notably, this descriptor comprises two scale parameters;a local scale parameter describing the amount of smoothing used in derivative computations, and an integration scale parameter determining over how large a region in space the statistics of regional descriptors is accumulated. Experimental results for both synthetic and natural images are presented, and the relation with models of biological vision is briefly discussed.

关键词： computer vision

来源：评论

学校读者我要写书评

暂无评论

DETECTING SALIENT BLOB-LIKE IMAGE STRUCTURES AND THEIR SCALES WITH A SCALE-SPACE PRIMAL SKETCH - A METHOD FOR FOCUS-OF-ATTENTION

引用

INTERNATIONAL JOURNAL OF computer vision 1993年第3期11卷 283-318页

作者： LINDEBERG, T 1. Computational Vision and Active Perception Laboratory (CVAP) Department of Numerical Analysis and Computing Science Royal Institute of Technology S-100 44 Stockholm Sweden

This article presents: (i) a multiscale representation of grey-level shape called the scale-space primal sketch, which makes explicit both features in scale-space and the relations between structures at different scales, (ii) a methodology for extracting significant blob-like image structures from this representation, and (iii) applications to edge detection, histogram analysis, and junction classification demonstrating how the proposed method can be used for guiding later-stage visual processes. The representation gives a qualitative description of image structure, which allows for detection of stable scales and associated regions of interest in a solely bottom-up data-driven way. In other words, it generates coarse segmentation cues, and can hence be seen as preceding further processing, which can then be properly tuned. It is argued that once such information is available, many other processing tasks can become much simpler. Experiments on real imagery demonstrate that the proposed theory gives intuitive results.

关键词： Dermal denticles Explicit Sketches BALANCES images Scale squama visual processing Imagery (Psychotherapy) Image IMAGE STRUCTURE scales

来源：评论

学校读者我要写书评

暂无评论

Point reconstruction from noisy images

引用

Journal of Mathematical Imaging and vision 1995年第1期5.0卷 77-90页

作者： Andersson, Magnus Betsis, Demetrios Department of Numerical Analysis and Computing Science Royal Institute of Technology Computational Vision and Active Perception Laboratory (CVAP) Stockholm S-100 44 Sweden

In this paper we treat the problem of determining optimally (in the least-squares sense) the 3D coordinates of a point, given its noisy images formed by any number of cameras of known geometry. The optimality criterion is determined by the covariance matrices associated with the images of the point. The covariance matrices are not restricted to be positive definite but are allowed to be singular. Thus, image points constrained to lie along straight lines can be handled as well. Estimation of the covariance of the reconstructed point is provided. The often appearing two-camera stereo case is treated in detail. It is shown in this case that, under reasonable conditions, the main step of the reconstruction reduces to finding the unique zero of a sixth degree polynomial in the interval (0, 1). © 1995 Kluwer Academic Publishers.

关键词： covariance matrix least-squares estimate reconstruction stereo

来源：评论

学校读者我要写书评

暂无评论

Shape from texture for smooth curved surfaces in perspective projection

引用

Journal of Mathematical Imaging and vision 1992年第4期2卷 327-350页

作者： Gårding, Jonas Computational Vision and Active Perception Laboratory (CVAP) Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm S-100 44 Sweden

Projective distortion of surface texture observed in a perspective image can provide direct information about the shape of the underlying surface. Previous theories have generally concerned planar surfaces;this paper presents a systematic analysis of first- and second-order texture distortion cues for the case of a smooth, curved surface. In particular, several kinds of texture gradients are analyzed and are related to surface orientation and surface curvature. The local estimates obtained from these cues can be integrated to obtain a global surface shape, and it is shown that the two surfaces resulting from the well-known tilt ambiguity in the local foreshortening cue typically have qualitatively different shapes. As an example of a practical application of the analysis, a shape-from-texture algorithm based on local orientation-selective filtering is described, and some experimental results are shown. © 1992 Kluwer Academic Publishers.

关键词： curved surfaces monocular cues perspective projection shape from texture texture gradients

来源：评论

学校读者我要写书评

暂无评论

SHAPE FROM TEXTURE FOR SMOOTH CURVED SURFACES 2nd

引用

2ND EUROPEAN CONF ON computer vision ( ECCV 92 )

作者： GARDING, J Computational Vision and Active Perception Laboratory (CVAP) Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm S-100 44 Sweden

ISBN: (纸本)3540554262

Projective distortion of surface texture observed in a perspective image can provide direct information about the shape of the underlying surface. Previous theories have generally concerned planar surfaces;in this paper we present a systematic analysis of first- and second-order texture distortion cues for the case of a smooth curved surface. In particular, we analyze several kinds of texture gradients and relate them to surface orientation and surface curvature. The local estimates obtained from these cues can be integrated to obtain a global surface shape, and we show that the two surfaces resulting from the well-known tilt ambiguity in the local foreshortening cue typically have qualitatively different shapes. As an example of a practical application of the analysis, a shape from texture algorithm based on local orientation-selective filtering is described, and some experimental results are shown. © Springer-Verlag Berlin Heidelberg 1992.

关键词： computer vision

来源：评论

学校读者我要写书评

暂无评论

Structure from translational observer motion

引用

International Workshop on Algebraic Frames for the perception and Action Cycle, AFPAC 1997

作者： Naeve, Ambjörn Computational Vision and Active Perception Laboratory Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm100 44 Sweden

ISBN: (纸本)3540635173

This work presents a unified, globally based geometric framework, using congruence geometry, for the description and computation of structure from motion. It is based on projectively invariant tangent information in a sequence of monocular images, i. e. occluding contours under general perspective. The strength of the framework is demonstrated by applying it to the case of translational observer motion, a type of motion that is of great practical importance since it can be easily implemented with the help of various gyroscopic devices. Introducing a simple technique for the computation of the direction of motion ("Focus Of Expansion") as a function of time, the recovery of translational observer motion is reduced to a problem of determining its speed. From such speed information, we show how to reconstruct the observer motion-as well as a set of silhouette curves on the observed target-and illustrate with a few simulated examples. The FOE-reconstraction method is then generalized from the real to the complex domain, showing how to combine conjugate complex geometric elements in order to obtain real geometric information concerning the direction of observer motion. We conclude by applying this method to real image data. © Springer-Verlag Berlin Heidelberg 1997.

关键词： Geometry

来源：评论

学校读者我要写书评

暂无评论

Object and pose recognition using contour and shape information

Object and pose recognition using contour and shape informat...

引用

12th International Conference on Advanced Robotics, 2005. ICAR '05

作者： Cornelius, Hugo Kragic, Danica Eklundh, Jan-Olof Computational Vision and Active Perception Laboratory Centre for Autonomous Systems Stockholm Sweden Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm Sweden

ISBN: (纸本)0780391772

Object recognition and pose estimation are of significant importance for robotic visual servoing, manipulation and grasping tasks. Traditionally, contour and shape based methods have been considered as most adequate for estimating stable and feasible grasps, [1]. More recently, a new research direction has been advocated in visual servoing where image moments are used to define a suitable error function to be minimized. Compared to appearance based methods, contour and shape based approaches are also suitable for use with range sensors such as, for example, lasers. In this paper, we evaluate a contour based object recognition system building on the method in [2], suitable for objects of uniform color properties such as cups, cutlery, fruits etc. This system is one of the building blocks of a more complex object recognition system based both on stereo and appearance cues, [3]. The system has a significant potential both in terms of service robot and programming by demonstration tasks. Experimental evaluation shows promising results in terms of robustness to occlusion and noise. © 2005 IEEE.

关键词： Industrial robots

来源：评论

学校读者我要写书评

暂无评论

A person following behaviour for a mobile robot

A person following behaviour for a mobile robot

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： H. Sidenbladh D. Kragic H.I. Christensen Computer Vision and Active Perception Lab Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm Sweden Centre for Autonomous Systems Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm Sweden

In this paper, a person following behaviour for a mobile robot is presented. The head of the person is located using skin colour detection. Then, a control loop is fed with the camera movements required to put the upper part of the person in the center of the image. The algorithm was tested in different rooms of a research lab. It performed well in all lighting conditions except in direct sunlight. Since the background and lighting cannot be controlled, the vision algorithm must be robust to such changes. However, since the computing power is quite limited, the algorithm must have as low complexity as possible.

关键词： Mobile robots Robot vision systems Cameras computer vision Skin Image motion analysis numerical analysis Lighting control Humans Machine vision

来源：评论

学校读者我要写书评

暂无评论

Tracking techniques for visual servoing tasks

Tracking techniques for visual servoing tasks

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： D. Kragic H.I. Christensen Computer Vision and Active Perception Lab Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm Sweden Centre for Autonomous Sys Department of Numerical Analysis and Computing Science Royal Institute of Technology Stockholm Sweden

Many of today's visual servoing systems rely on the use of markers on the object to provide features for control. There is thus a need for a visual system that provides control features regardless of the appearance of the object. Region based tracking is a natural approach since it does not require any special type of features. In this paper we present two different approaches to region based tracking: 1) a multi-resolution gradient based approach (using optical flow); and 2) a discrete feature based search approach. We present experiments conducted with both techniques for different types of image motions. Finally, the performance, drawbacks and limitations of used techniques are discussed.

关键词： Visual servoing Robots Tracking computer vision numerical analysis Control systems Grippers Image motion analysis Motion estimation Visual system

来源：评论

学校读者我要写书评

暂无评论

Integrating task-directed plaiming with reactive object recognition 12

Integrating task-directed plaiming with reactive object reco...

引用

Intelligent Robots and computer vision XII: Algorithms and Techniques 1993

作者： Dickinson, Sven Stevenson, Suzanne Amdur, Eugene Tsotsos, John Olsson, Lars Department of Computer Science University of Toronto 6 King's College Rd. TorontoONM5S1A4 Canada Computational Vision and Active Perception Laboratory Dept. of Numerical Analysis and Computing Science Royal Institute of Tecimology StockholmS-10044 Sweden

We describe a robot vision system that achieves complex object recognition with two layers of behaviors, performing the tasks of planning and object recognition, respectively. The recognition layer is a pipeline in which successive stages take in images from a stereo head, recover relevant features, build intermediate representations, and deposit 3-D objects into a world model. Each stage is an independent process that reacts automatically to output from the previous stage. This reactive system operates continuously and autonomously to construct the robot's 3-D model of the environment. Sitting above the recognition pipeline is the planner which is responsible for populating the world model with objects that satisfy the high-level goals of the system. For example, upon examination of the world model, the planner can decide to direct the head to another location, gating new images into the recognition pipeline, causing new objects to be deposited into the world model. Alternatively, the planner can alter the recognition behavior of the pipeline so that objects of a certain type or at a certain location appear in the world model. © 1993 SPIE.

关键词： Pipelines

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：