3D reconstruction of highly textured surfaces on unvegetated terrain is of major interest for stereo vision based mapping applications. We describe a prototype system for automatic modeling of such scenes. It is based...
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ISBN:
(纸本)0819423068;9780819423061
3D reconstruction of highly textured surfaces on unvegetated terrain is of major interest for stereo vision based mapping applications. We describe a prototype system for automatic modeling of such scenes. It is based on two frame CCD cameras, which are tightly attached to each other ensuring constant relative orientation. One camera is used to acquire known reference points to get the exterior orientation of the system, the other records the surface images. The system is portable to keep image acquisition as short as possible. Automatic calibration using the images acquired by the calibration camera permits the computation of exterior orientation parameters of the surface camera via a transformation matrix. A robust matching method providing dense disparities together with a flexible reconstruction algorithm renders an accurate grid of 3D points on arbitrarily shaped surfaces. The results of several stereo reconstructions are merged. Projection onto the global shape allows easy evaluation of volumes, and thematic mapping with respect to the desired surface geometry in construction processes. We report on accuracy and emphasize on the practical usage. It is shown that the prototpye system is able to generate a proper data set of surface descriptions that is accurate and dense enough to serve as documentation, planning and accounting basis.
If the nuclear retinal layers of the human eye are interpreted as 3D phase gratings, the aperture effects in human vision, namely the Stiles-Crawford effects I and II and trichromatic vision, can be explained in terms...
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ISBN:
(纸本)0819423068;9780819423061
If the nuclear retinal layers of the human eye are interpreted as 3D phase gratings, the aperture effects in human vision, namely the Stiles-Crawford effects I and II and trichromatic vision, can be explained in terms of interference optics. A multilayer grating situated in the image plane of the eye fixes the direction of the diffraction orders through its 3D geometry. The ratio between λ' or ν' of the light cone incident at an angle and λ and ν of the cone incident at 0 degrees can thus be differentiated as a brightness, hue and saturation shift in 3 chromatic RGB diffraction orders in the near field behind the grating, thus providing information on the relative position, distance, 3D shape and movement of objects in the 3D space. The direction cosine of the light cones in the von Laue equation means that lateral distances and movements relative to the visual axis and longitudinal movements relative to the focused distance give rise to the aperture effects and a space-time microrelief of the 3D world. This is regarded as an optical basis for monocular spatial vision and motion detection. Temporal patterns in human vision therefore produce spatial patterns and movement information and vice versa. The intrinsic oscillations of the nuclear layers transform the constant interference-optical object representations become possible. The interference-optical local lateral connections and the retinal feedback NN structure allow the possibility of parallel-optical image correlation in real time. The psychophysical transformations in the retinal 3D grating correspond to an image transformation into a reciprocal grating; the retinal clock is set adaptively by means of λmax of the 111 diffraction order and via the trichromatic white standard.
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.
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.
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.
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.
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.
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.
This paper describes the use of color segmentation to assist the detection of blemishes and other defects on fruit. It discusses the advantages and disadvantages of different color spaces including RGB and HSI and dif...
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ISBN:
(纸本)0819423068
This paper describes the use of color segmentation to assist the detection of blemishes and other defects on fruit. It discusses the advantages and disadvantages of different color spaces including RGB and HSI and different supervised learning techniques including maximum likelihood, nearest neighbor and neural networks. It then compares the performance of various combinations of these on the same training and test set. A selection of images segmented by the best combination is presented and conclusions made.
Current developments in the field of automated assembly systems show an increasing interest in systems that are flexible in both CAD based product design and CAD based assembly. For the application addressed in this p...
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ISBN:
(纸本)0819423068
Current developments in the field of automated assembly systems show an increasing interest in systems that are flexible in both CAD based product design and CAD based assembly. For the application addressed in this paper, coupling the vision system and a CAD database is of prime importance in order to achieve the required automatic reconfiguration of the assembly cell when new parts are defined. This paper presents a 3D CAD-based vision system for obtaining 3D data about the scene. After the images are acquired, edge detection is preformed and the detected edges are stored as chaincodes. Following that, a stereo vision algorithm is applied for finding the recognition features. The output are lists of features that are combined into a 3D wireframe representing the scene. The recognition algorithm takes the observed wireframe outputs from the stereo vision system, and compares them with a set of model wireframes derived from previous models, in order to select the 'best match', where the previous models used for recognition are derived from a product data model (PDM). The PDM is an interface between the CAD database and the recognition system, which allows the automatic generation of new models when new parts are introduced into the system. The vision system described in this paper is part of an intelligent robotic assembly cell, where the aim is to build a flexible intelligent robotic assembly cell, such that robots would be able to automatically assemble a random variety of small-batch products.
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