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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

On the design and implementation of decision-theoretic, interactive, and vision-driven mobile robots

Elinas, Pantelis 05 1900 (has links)
We present a framework for the design and implementation of visually-guided, interactive, mobile robots. Essential to the framework's robust performance is our behavior-based robot control architecture enhanced with a state of the art decision-theoretic planner that takes into account the temporal characteristics of robot actions and allows us to achieve principled coordination of complex subtasks implemented as robot behaviors/skills. We study two different models of the decision theoretic layer: Multiply Sectioned Markov Decision Processes (MSMDPs) under the assumption that the world state is fully observable by the agent, and Partially Observable Markov Decision Processes (POMDPs) that remove the latter assumption and allow us to model the uncertainty in sensor measurements. The MSMDP model utilizes a divide-and-conquer approach for solving problems with millions of states using concurrent actions. For solving large POMDPs, we present heuristics that improve the computational efficiency of the point-based value iteration algorithm while tackling the problem of multi-step actions using Dynamic Bayesian Networks. In addition, we describe a state-of-the-art simultaneous localization and mapping algorithm for robots equipped with stereo vision. We first present the Monte-Carlo algorithm sigmaMCL for robot localization in 3D using natural landmarks identified by their appearance in images. Secondly, we extend sigmaMCL and develop the sigmaSLAM algorithm for solving the simultaneous localization and mapping problem for visually-guided, mobile robots. We demonstrate our real-time algorithm mapping large, indoor environments in the presence of large changes in illumination, image blurring and dynamic objects. Finally, we demonstrate empirically the applicability of our framework for developing interactive, mobile robots capable of completing complex tasks with the aid of a human companion. We present an award winning robot waiter for serving hors d'oeuvres at receptions and a robot for delivering verbal messages among inhabitants of an office-like environment.
22

Practical visual odometry for small embedded systems

Schaerer, Shawn S. 19 September 2006 (has links)
Localization and mapping are important abilities for any robot to have if it wants to navigate intelligently in the real world. The goal of the research designed in this thesis was to develop a practical embedded visual odometer that utilized common features found in real world environments. The visual odometer is a system that measures the self motion of a mobile robot using visual feeback. The developed visual odometer was tested on a custom mobile robot in several different tests that were derived from the robotic soccer domain. This system’s performance was compared to two other systems. These systems were a KLT feature tracker based robot and a commercial shaft encoder based robot. The results of the completed tests showed that the developed visual odometer’s performance was less than expected. It also showed that this system has good potential. As well, the test results showed the limitations of using a KLT feature tracker based robot and that the commercial shaft encoder based robot also had performance less than expected.
23

Image acquisition and processing with AC-coupled cameras

Urey, Hakan 12 1900 (has links)
No description available.
24

Constraints for robust motion analysis

Gardner, Warren F. 06 1900 (has links)
No description available.
25

Robust statistics for computer vision : model fitting, image segmentation and visual motion analysis

Wang, Hanzi January 2004 (has links)
Abstract not available
26

Spiral Architecture for Machine Vision

January 1996 (has links)
This thesis presents a new and powerful approach to the development of a general purpose machine vision system. The approach is inspired from anatomical considerations of the primate's vision system. The geometrical arrangement of cones on a primate's retina can be described in terms of a hexagonal grid. The importance of the hexagonal grid is that it possesses special computational features that are pertinent to the vision process. The fundamental thrust of this thesis emanates from the observation that this hexagonal grid can be described in terms of the mathematical object known as a Euclidean ring. The Euclidean ring is employed to generate an algebra of linear transformations which are appropriate for the processing of multidimensional vision data. A parallel autonomous segmentation algorithm for multidimensional vision data is described. The algebra and segmentation algorithm are implemented on a network of transputers. The implementation is discussed in the context of the outline of a general purpose machine vision system's design.
27

Representing junctions through asymmetric tensor diffusion

Arseneau, Shawn. January 2006 (has links)
Gradient-based junctions form key features in such applications as object classification, motion segmentation, and image enhancement. Asymmetric junctions arise from the merging of an odd number of contour end-points such as at a 'Y' junction. Without an asymmetric representation of such a structure, it will be identified in the same category as 'X' junctions. This has severe consequences when distinguishing between features in object classification, discerning occlusion from disocclusion in motion segmentation and in properly modeling smoothing boundaries in image enhancement. / Current junction analysis methods include convolution, which applies a mask over a sub-region of the image, and diffusion, which propagates gradient information from point-to-point based on a set of rules. / A novel method is proposed that results in an improved approximation of the underlying contours, through the use of asymmetric junctions. The method combines the ability to represent asymmetric information, as do a number of convolution methods, with the robustness of local support obtained from diffusion schemes. This work investigates several different design paradigms of the asymmetric tensor diffusion algorithm. The proposed approach proved superior to existing techniques by properly accounting for asymmetric junctions over a wide range of scenarios.
28

Camera-independent learning and image quality assessment for super-resolution

Bégin, Isabelle. January 2007 (has links)
An increasing number of applications require high-resolution images in situations where the access to the sensor and the knowledge of its specifications are limited. In this thesis, the problem of blind super-resolution is addressed, here defined as the estimation of a high-resolution image from one or more low-resolution inputs, under the condition that the degradation model parameters are unknown. The assessment of super-resolved results, using objective measures of image quality, is also addressed. / Learning-based methods have been successfully applied to the single frame super-resolution problem in the past. However, sensor characteristics such as the Point Spread Function (PSF) must often be known. In this thesis, a learning-based approach is adapted to work without the knowledge of the PSF thus making the framework camera-independent. However, the goal is not only to super-resolve an image under this limitation, but also to provide an estimation of the best PSF, consisting of a theoretical model with one unknown parameter. / In particular, two extensions of a method performing belief propagation on a Markov Random Field are presented. The first method finds the best PSF parameter by performing a search for the minimum mean distance between training examples and patches from the input image. In the second method, the best PSF parameter and the super-resolution result are found simultaneously by providing a range of possible PSF parameters from which the super-resolution algorithm will choose from. For both methods, a first estimate is obtained through blind deconvolution and an uncertainty is calculated in order to restrict the search. / Both camera-independent adaptations are compared and analyzed in various experiments, and a set of key parameters are varied to determine their effect on both the super-resolution and the PSF parameter recovery results. The use of quality measures is thus essential to quantify the improvements obtained from the algorithms. A set of measures is chosen that represents different aspects of image quality: the signal fidelity, the perceptual quality and the localization and scale of the edges. / Results indicate that both methods improve similarity to the ground truth and can in general refine the initial PSF parameter estimate towards the true value. Furthermore, the similarity measure results show that the chosen learning-based framework consistently improves a measure designed for perceptual quality.
29

En-co.de : a web service for augmenting physical objects with an active digital presence

Westing, Brandt Michael 16 December 2013 (has links)
It is now possible for physical objects to have a dynamic digital presence via active identification codes that can be scanned via ubiquitous devices such as smart phones or tablets. En-co.de is a web service for the generation, storing, retrieval, and augmentation of metadata associated with physical objects. The service is built upon the concept that metadata associated with an object can be retrieved through a Quick Response (QR) coded URL. En-co.de serves to link a physical entity to a digital archive of information and provides services such as geolocation and SMS text alerts when an object's identifier, or tag, is scanned. I provide an analysis of QR code qualitative characteristics, the architecture for the en-co.de web service, a scalability study of the en-co.de architecture, and the results of the completed service in production in this report. In addition, the analysis is complemented with an evaluation of comparable identification schemes and web services. / text
30

Examine vision technology for small object recognition in an industrial robotics application

Martinsson, Jonas January 2015 (has links)
This thesis explains the development of a computer vision system able to find and orient relatively small objects. The motivations is exchanging a monotonous work done by hand and replace it with an automation system with help of an ABB IRB 140 industrial robot. The vision system runs on a standard PC and is developed using the OpenCV environment, originally made by Intel in Russia. The algorithms of the system is written in C++ and the user interface in C++/CLI. With a derived test case, multiple vision algorithms is tested and evaluated for this kind of application. The result shows that SIFT/SURF works poorly with multiple instances of the search object and HAAR classifiers produces many false positives. Template matching with image moment calculation gave a satisfying result regarding multiple object in the scene and produces no false positives. Drawbacks of the selected algorithm developed where sensibility to light invariance and lack of performance in a skewed scene. The report also contains suggestions on how to precede with further improvements or research.

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