Feature point tracking from an image sequence is an important step in many methods of image understanding including shape from motion and mobile robot navigation. Assuming an affine camera model, this paper proposed a...
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ISBN:
(纸本)0819423068;9780819423061
Feature point tracking from an image sequence is an important step in many methods of image understanding including shape from motion and mobile robot navigation. Assuming an affine camera model, this paper proposed a new tracking method using affine invariance. Any 3D feature point can have unique coordinates with reference to an affine basis and the affine coordinates are invariant to affine transformation: camera rotations and translations. The images of a set of 4 control points defining an affine basis are tracked in an image sequence using a conventional method. Under this assumption, given a feature point in any image, its locus in the first image is a straight line. The straight lines of the corresponding features from the image sequence will intersect at a point, the corresponding feature point, in the first image. A Hough transform technique is designed to detect this intersection point and track the corresponding feature points in the image sequence. This technique is suitable for tracking a large number of feature points. Its performance is practically unaffected by missing features in some images and large motion steps. Accurate and reliable results had been obtained in real experiments using the method.
We consider two problems: first, the problem of detection of objects in images of 3D planetary terrain; second, the task of finding corresponding points for stereo matching of this type of images. We propose an approa...
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ISBN:
(纸本)0819423068;9780819423061
We consider two problems: first, the problem of detection of objects in images of 3D planetary terrain; second, the task of finding corresponding points for stereo matching of this type of images. We propose an approach that is simultaneously applicable to both problem areas. The approach uses a bank of filters based on different 2D Gabor functions. By detection we mean locating multiple classes of targets with distortions present and in a cluttered background. It is desirable to minimize false alarms due to clutter, image noise, and the presence of other objects. In the scenario of stereo matching, the pixel location where we search for the corresponding point is the target, while all ambiguous matches are non-targets. In this work, we use Gabor filter banks in two versions. First, for fast detection of targets, the single filter outputs of the bank are fused by linear combination. Second, for stereo matching, the outputs of the filters form a feature vector used to find the best match. We refer to both types of filters as a macro Gabor filter. In the linear combination case, the filter bank forms a single filter. This filter is correlated with an input image, followed by local maximum detection, and thresholding to yield the finally detected targets. The new aspects are: combining real and imaginary parts of GFs into one filter using centered on off-center GFs, separately optimizing the fusion coefficients of the GFs by controlling the shape of the correlation outputs of each filter alone, and the application to two different scenarios.
Fuzzy logic has been promoted recently by many researchers for the design of navigational algorithms for mobile robots. The new approach fits in well with a behavior-based autonomous systems framework, where common-se...
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ISBN:
(纸本)0819423068
Fuzzy logic has been promoted recently by many researchers for the design of navigational algorithms for mobile robots. The new approach fits in well with a behavior-based autonomous systems framework, where common-sense rules can naturally be formulated to create rule-based navigational algorithms, and conflicts between behaviors may be resolved by assigning weights to different rules in the rule base. The applicability of the techniques has been demonstrated for robots that have used sensor devices such as ultrasonics and infrared detectors. However, the implementation issues relating to the development of vision-based, fuzzy-logic navigation algorithms do not appear, as yet, to have been fully explored. The salient features that need to be extracted from an image for recognition or collision avoidance purposes are very much application dependent;however, the needs of an autonomous mobile vehicle cannot be known fully 'a priori'. Similarly, the issues relating to the understanding of a vision generated image which is based on geometric models of the observed objects have an important role to play;however, these issues have not as yet been either addressed or incorporated into the current fuzzy logic-based algorithms that have been purported for navigational control. This paper attempts to address these issues, and attempts to come up with a suitable framework which may clarify the implementation of navigation algorithms for mobile robots that use vision sensor/s and fuzzy logic for map building, target location, and collision avoidance. The scope for application of this approach is demonstrated.
Specifications and design are provided for a low-cost scatterometer build to study the relationship between optical scatter and image formation. Design principles and considerations are discussed as they relate to dig...
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ISBN:
(纸本)0819423068
Specifications and design are provided for a low-cost scatterometer build to study the relationship between optical scatter and image formation. Design principles and considerations are discussed as they relate to digital imaging. Specifications and instrument limitations both mechanical and optical are examined and certain design choices are explained. The process of calibrating the instrument is considered and methods of noise suppression both electronic and optical are discussed. Finally, some measured data is presented.
In this paper, we present a low-cost vision based system for handling of hazardous waste in an unstructured environment. The prototype system described shows the feasibility of sorting and removal of randomly mixed an...
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ISBN:
(纸本)0819423068
In this paper, we present a low-cost vision based system for handling of hazardous waste in an unstructured environment. The prototype system described shows the feasibility of sorting and removal of randomly mixed and oriented flexible objects from a bin using inexpensive and widely available hardware. Our experiments show that the utilization of even the simplest constructs is sufficient for the manipulation of flexible objects.
An automatic raw material selector into 3-4 groups depending on the crystal shape is developed. As signs of selection there are used dimensions of the crystal image, position of the image center in the bearing plan as...
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ISBN:
(纸本)0819423068
An automatic raw material selector into 3-4 groups depending on the crystal shape is developed. As signs of selection there are used dimensions of the crystal image, position of the image center in the bearing plan as well as dimensions and proportion of two interperpendicular chords crossing the image center. The device sorts out into 3-4 groups 8 crystals per second.
A real-time vergence control mechanism based on log-polar images developed for a robot head is described. The real-time control of activevision systems imposes strong constraints on the computational complexity of th...
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A real-time vergence control mechanism based on log-polar images developed for a robot head is described. The real-time control of activevision systems imposes strong constraints on the computational complexity of the visionalgorithms. It is illustrated that vergence of a stereo head can be achieved at reduced computational cost using log-polar images. The main advantages of using a non-uniform image sampling mechanism, such as the log-polar images, are related both to perceptual and algorithm complexity issues. It is shown that when using correlation measures to control vergence, log-polar images give better results than cartesian images. Two algorithms for closed loop vergence control, using correlation measures over log-polar images, are proposed. The two algorithms are compared in the test examples and the problem of designing and adequate log-polar sensor is addressed by introducing a performance analysis.
Robust range estimation is one of the most important tasks in mobile robotics. This paper presents a new optical arrangement for utilizing the previously known 'depth from defocus' principle. The arrangement m...
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ISBN:
(纸本)0819423068
Robust range estimation is one of the most important tasks in mobile robotics. This paper presents a new optical arrangement for utilizing the previously known 'depth from defocus' principle. The arrangement makes it possible to apply standard video lenses and camera modules for making a compact range camera system. Real-time processing is made possible with a single-board DSP card.
A special case of civilian activevision has been investigated here, namely, a vision system by car anti-fog headlamps. A method to estimate the light-engineering criteria for headlamp performances and simulate the op...
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ISBN:
(纸本)0819423068
A special case of civilian activevision has been investigated here, namely, a vision system by car anti-fog headlamps. A method to estimate the light-engineering criteria for headlamp performances and simulate the operation of the system through a turbid medium, such as fog, is developed on the base of the analytical procedures of the radiative transfer theory. This method features in include the spaced light source and receiver of a driver's activevision system, the complicated azimuth-nonsymmetrical emissive pattern of the headlamps, and the fine angular dependence of the fog phase function near the backscattering direction. The final formulas are derived in an analytical form providing additional convenience and simplicity for the computations. The image contrast of a road object with arbitrary orientation, dimensions, and shape and its limiting visibility range are studied as a function of meteorological visibility range in fog as well as of various emissive pattern, mounting, and adjustment parameters of the headlamps. Optimization both light-engineering and geometrical characteristics of the headlamps is shown to be possible to enable the opportunity to enhance the visibility range and, hence, traffic safety.
Based on the concept of object- and behavior-oriented stereo vision, a method is introduced which enables a robot manipulator to handle two distinct types of objects. It uses an uncalibrated stereo vision system and a...
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ISBN:
(纸本)0819423068
Based on the concept of object- and behavior-oriented stereo vision, a method is introduced which enables a robot manipulator to handle two distinct types of objects. It uses an uncalibrated stereo vision system and allows a direct transition from image coordinates to motion control commands of a robot. An object can be placed anywhere in the robot's 3D work space which is in the field of view of both cameras. The objects to be manipulated can either be of flat cylindrical or elongate shape. Results gained from real-world experiments are discussed.
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