The problem of object recognition is addressed. In the literature this task has been generally considered in a 'passive' perspective, where everything is static and there is no definite relation between the ob...
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ISBN:
(纸本)0818658258
The problem of object recognition is addressed. In the literature this task has been generally considered in a 'passive' perspective, where everything is static and there is no definite relation between the object and its environment. We propose an 'active' approach for object recognition, based on the capability of the observer to move and give a better description of the object under consideration and also to take advantage of the relations between the objects and the environment. This can be accomplished at the task level and at the sensor level. The face recognition problem, based on the face-space approach, is considered to demonstrate the advantage of adopting an active retina to sample the face, build a database and perform the recognition task. By using an active space-variant retina the size of the database is considerably reduced and consequently also the processing time for recognition. A comparative experiment using the active and static approach is presented.
We propose an affine framework for perspective views, captured by a single extremely simple equation based on a viewer-centered invariant we call relative affine structure. Via a number of corollaries of our main resu...
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ISBN:
(纸本)0818658258
We propose an affine framework for perspective views, captured by a single extremely simple equation based on a viewer-centered invariant we call relative affine structure. Via a number of corollaries of our main results we show that our framework unifies previous work - including Euclidean, projective and affine - in a natural and simple way. Finally, the main results were applied to a real image sequence for purpose of 3D reconstruction from 2D views.
No feature-based vision system can work unless good features can be identified and tracked from frame to frame. Although tracking itself is by and large a solved problem, selecting features that can be tracked well an...
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ISBN:
(纸本)0818658258
No feature-based vision system can work unless good features can be identified and tracked from frame to frame. Although tracking itself is by and large a solved problem, selecting features that can be tracked well and correspond to physical points in the world is still hard. We propose a feature selection criterion that is optimal by construction because it is based on how the tracker works, and a feature monitoring method that can detect occlusions, disocclusions, and features that do not correspond to points in the world. These methods are based on a new tracking algorithm that extends previous Newton-Raphson style search methods to work under affine image transformations. We test performance with several simulations and experiments.
This paper presents a Radon transform-based approach to the detection of linear features in images characterized by high noise levels. This approach is based on the localized radon transform where the intensity integr...
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ISBN:
(纸本)0818658258
This paper presents a Radon transform-based approach to the detection of linear features in images characterized by high noise levels. This approach is based on the localized radon transform where the intensity integration is performed over short line segments rather than across the entire image. The algorithm, referred to as the feature space line detector (FSLD) algorithm, is tested on synthetic images of linear features with very high noise levels. The results of this testing demonstrate the algorithm's robustness in the presence of noise, as well as its ability to detect and localize linear features that are significantly shorter than the image dimensions or that display some curvature.
In this paper, we propose a snake-based approach that lets a user specify only the distant end points of the curve he wishes to delineate without having to supply an almost complete polygonal approximation. We achieve...
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ISBN:
(纸本)0818658258
In this paper, we propose a snake-based approach that lets a user specify only the distant end points of the curve he wishes to delineate without having to supply an almost complete polygonal approximation. We achieve much better convergence properties than those of traditional snakes by using the image information around these end points to provide boundary conditions and by introducing an optimization schedule that allows the snake to take image information into account first only near its extremities and then, progressively, towards its center. These snakes could be used to alleviate the often repetitive task practitioners have to face when segmenting images by abolishing the need to sketch a feature of interest in its entirety, that is, to perform a painstaking, almost complete, manual segmentation.
We described a system for detection and description of buildings in aerial scenes. This is a difficult task as the aerial images contain a variety of objects. Low-level segmentation processes give highly fragmented se...
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ISBN:
(纸本)0818658258
We described a system for detection and description of buildings in aerial scenes. This is a difficult task as the aerial images contain a variety of objects. Low-level segmentation processes give highly fragmented segments due to a number of reasons. We use a perceptual grouping approach to collect these fragments and discard those that come from other sources. We use shape properties of the buildings for this. We use shadows to help form and verify the hypotheses generated by the grouping process. This latter step also provides 3-D descriptions of the buildings. Our system has been tested on a number of examples and is able to work with overhead or oblique views.
This paper presents a new framework for the computation of shape and motion from a sequence of images taken under perspective projection. The framework is based on two abstractions, the picture and trail loci, that re...
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ISBN:
(纸本)0818658258
This paper presents a new framework for the computation of shape and motion from a sequence of images taken under perspective projection. The framework is based on two abstractions, the picture and trail loci, that represent respectively the set of all pictures of the same scene and the set of all trails that a point in the world can leave on the image for a given camera trajectory. These abstractions lead to a remarkably clean relation between perspective and orthography. A shape and motion reconstruction method is developed for the case of a two-dimensional world, but all concepts also hold in three dimensions. Experiments show that the method is rather immune to noise but critically dependent on camera calibration.
Searching for an object in a cluttered area is often complicated by the fact that the clutter hides portions of the area from view. Multiple viewpoints are often required. Previous viewpoint selection algorithms rely ...
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ISBN:
(纸本)0818658258
Searching for an object in a cluttered area is often complicated by the fact that the clutter hides portions of the area from view. Multiple viewpoints are often required. Previous viewpoint selection algorithms rely on models that represent the portions already viewed. Unfortunately, these models are often difficult to construct when the sensor position is imprecisely known and when the obtainable depth data is sparse. This paper questions whether scene models are really necessary for selecting viewpoints for search tasks. It investigates two alternative viewpoint selection methods that do not rely on such models. One constructs no representation and simply uses a fixed set of viewpoints, while the other selects viewpoints based on detected occluding edges. On average, both model-free methods compare very favorably to model-based methods, although additional work is necessary to ensure that they abort in a timely manner when the desired object cannot be found.
Situations involving navigation among maneuvering agents are critical for the study of visual guidance of autonomous vehicles. This paper addresses the case of translational motion with polynomial regimes and defines ...
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ISBN:
(纸本)0818658258
Situations involving navigation among maneuvering agents are critical for the study of visual guidance of autonomous vehicles. This paper addresses the case of translational motion with polynomial regimes and defines a general class of temporal parameters (TP) relevant for navigation, enable a qualitative description of the observed agents' depth trajectories. These parameters are shown to be visually recoverable. Instances of such temporal parameters include Time-to-Collision (TTC) and Time-to-Synchronization (TTS), useful for docking or platooning maneuvers. The results are specialized to lower order motions. The recovery of TTC and TTS for arbitrary regimes is a special corollary of our analysis. Computations from direct and feature-based methods are described. A scheme for addressing model order determination, collision detection and temporal parameter estimation is proposed and tested. Experimental results on synthetic and real images are given.
This paper describes an investigation into the use of parametric 2D models describing the movement of edges for the determination of possible 3D shape and hence function of an object. An assumption of this research is...
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ISBN:
(纸本)0818658258
This paper describes an investigation into the use of parametric 2D models describing the movement of edges for the determination of possible 3D shape and hence function of an object. An assumption of this research is that the camera can foveate and track particular features. It is argued that simple 2D analytic descriptions of the movement of edges can infer 3D shape while the camera is moved. This uses an advantage of foveation i.e. the problem becomes object centred. The problem of correspondence for numerous edge points is overcome by the use of a tree based representation for the competing hypotheses. Numerous hypothesis are maintained simultaneously and it does not rely on a single kinematic model which assumes constant velocity or acceleration. The numerous advantages of this strategy are described.
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