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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.
161

Haptic interaction with rigid body objects in a simulated environment

Engström, Per January 2006 (has links)
<p>The purpose of this report is to cover the procedure of creating and explaining how to use a tool kit that allows the haptic Application Programming Interface (API) H3D from SenseGraphics to be used in conjunction with an advanced physics simulator from Meqon. Both haptic applications and physics engines have developed rapidly the last couple of years but they are rarely used together. If such a connection would be created it would be possible to interact with complex environments in a new way and a variety of haptic applications can be produced.</p><p>The physics engine from Meqon has gained recognition for its abilities to produce realistic results due to efficient implementation of collision detection system, friction models and collision handling, among other things. H3D is a completely open source API that is based on standards such as OpenGL and X3D. H3D consists of a data base containing nodes, an XML parser to extract a scene graph from the data base and functionality to produce a graphic and haptic interface.</p><p>The tool kit produced in this thesis is an extension to H3D. A fundamental function of the tool kit is to communicate with the Meqon system and still be a part of the H3D structure. The Meqon system has a modular structure where each module has its own abilities. Only the rigid body module is utilised by the tool kit, which however is the most important module. It is possible to define global settings of the engine and rigid body module, add rigid bodies with several elements and insert constraints on the motion of the rigid bodies into the engine. All of these operations are done from the X3D file format that H3D uses, thus letting all functionality of the H3D system available.</p>
162

Visualization and Haptics for Interactive Medical Image Analysis / Visualisering och Haptik för Interaktiv Medicinsk Bildanalys

Vidholm, Erik January 2008 (has links)
Modern medical imaging techniques provide an increasing amount of high-dimensional and high-resolution image data that need to be visualized, analyzed, and interpreted for diagnostic and treatment planning purposes. As a consequence, efficient ways of exploring these images are needed. In order to work with specific patient cases, it is necessary to be able to work directly with the medical image volumes and to generate the relevant 3D structures directly as they are needed for visualization and analysis. This requires efficient tools for segmentation, i.e., separation of objects from each other and from the background. Segmentation is hard to automate due to, e.g., high shape variability of organs and limited contrast between tissues. Manual segmentation, on the other hand, is tedious and error-prone. An approach combining the merits from automatic and manual methods is semi-automatic segmentation, where the user interactively provides input to the methods. For complex medical image volumes, the interactive part can be highly 3D oriented and is therefore dependent on the user interface. This thesis presents methods for interactive segmentation and visualization where true 3D interaction with haptic feedback and stereo graphics is used. Well-known segmentation methods such as fast marching, fuzzy connectedness, live-wire, and deformable models, have been tailored and extended for implementation in a 3D environment where volume visualization and haptics are used to guide the user. The visualization is accelerated with graphics hardware and therefore allows for volume rendering in stereo at interactive rates. The haptic feedback is rendered with constraint-based direct volume haptics in order to convey information about the data that is hard to visualize and thereby facilitate the interaction. The methods have been applied to real medical images, e.g., 3D liver CT data and 4D breast MR data with good results. To provide a tool for future work in this area, a software toolkit containing the implementations of the developed methods has been made publicly available.
163

Haptic interaction with rigid body objects in a simulated environment

Engström, Per January 2006 (has links)
The purpose of this report is to cover the procedure of creating and explaining how to use a tool kit that allows the haptic Application Programming Interface (API) H3D from SenseGraphics to be used in conjunction with an advanced physics simulator from Meqon. Both haptic applications and physics engines have developed rapidly the last couple of years but they are rarely used together. If such a connection would be created it would be possible to interact with complex environments in a new way and a variety of haptic applications can be produced. The physics engine from Meqon has gained recognition for its abilities to produce realistic results due to efficient implementation of collision detection system, friction models and collision handling, among other things. H3D is a completely open source API that is based on standards such as OpenGL and X3D. H3D consists of a data base containing nodes, an XML parser to extract a scene graph from the data base and functionality to produce a graphic and haptic interface. The tool kit produced in this thesis is an extension to H3D. A fundamental function of the tool kit is to communicate with the Meqon system and still be a part of the H3D structure. The Meqon system has a modular structure where each module has its own abilities. Only the rigid body module is utilised by the tool kit, which however is the most important module. It is possible to define global settings of the engine and rigid body module, add rigid bodies with several elements and insert constraints on the motion of the rigid bodies into the engine. All of these operations are done from the X3D file format that H3D uses, thus letting all functionality of the H3D system available.
164

Towards Template Security for Iris-based Biometric Systems

Fouad, Marwa 18 April 2012 (has links)
Personal identity refers to a set of attributes (e.g., name, social insurance number, etc.) that are associated with a person. Identity management is the process of creating, maintaining and destroying identities of individuals in a population. Biometric technologies are technologies developed to use statistical analysis of an individual’s biological or behavioral traits to determine his identity. Biometrics based authentication systems offer a reliable solution for identity management, because of their uniqueness, relative stability over time and security (among other reasons). Public acceptance of biometric systems will depend on their ability to ensure robustness, accuracy and security. Although robustness and accuracy of such systems are rapidly improving, there still remain some issues of security and balancing it with privacy. While the uniqueness of biometric traits offers a convenient and reliable means of identification, it also poses the risk of unauthorized cross-referencing among databases using the same biometric trait. There is also a high risk in case of a biometric database being compromised, since it’s not possible to revoke the biometric trait and re-issue a new one as is the case with passwords and smart keys. This unique attribute of biometric based authentication system poses a challenge that might slow down public acceptance and the use of biometrics for authentication purposes in large scale applications. In this research we investigate the vulnerabilities of biometric systems focusing on template security in iris-based biometric recognition systems. The iris has been well studied for authentication purposes and has been proven accurate in large scale applications in several airports and border crossings around the world. The most widely accepted iris recognition systems are based on Daugman’s model that creates a binary iris template. In this research we develop different systems using watermarking, bio-cryptography as well as feature transformation to achieve revocability and security of binary templates in iris based biometric authentication systems, while maintaining the performance that enables widespread application of these systems. All algorithms developed in this research are applicable on already existing biometric authentication systems and do not require redesign of these existing, well established iris-based authentication systems that use binary templates.
165

Towards Diverse Media Augmented E-Book Reader Platform

Alam, Kazi Masudul 06 June 2012 (has links)
In order to leverage the use of various modalities such as audio-visual-touch in instilling learning behaviour, we present an intuitive approach of annotation based hapto-audio-visual interaction with the traditional digital learning materials such as eBooks. By integrating the traditional home entertainment system and respective media in the user's reading experience combined with haptic interfaces, we examine whether such augmentation of modalities influence the user's reading experience in terms of attention, entertainment and retention. The proposed Haptic E-Book (HE-Book) system leverages the haptic jacket, haptic arm band as well as haptic sofa interfaces to receive haptic emotive signals wirelessly in the form of patterned vibrations of the actuators and expresses the learning material by incorporating audio-video based augmentation in order to pave ways for intimate reading experience in the popular eBook platform. We have designed and developed desktop, mobile/tablet based HE-Book system as well as a semi-automated annotation authoring tool. Our system also supports multimedia based diverse quiz augmentations, which can help in learning tracking. We have conducted quantitative and qualitative tests using the developed prototype systems. We have adopted the indirect objective based performance analysis methodology, which is commonly used for multimedia based learning investigation. The user study shows that, there is a positive tendency of accepting multimodal interactions including haptics with traditional eBook reading experience. Though our limited number of laboratory tests reveal, that haptics can be an influencing media in eBook reading experience, but it requires large scale real life tests to provide a concluding remarks.
166

An Adaptive Approach to Exergames with Support for Multimodal Interfaces

Silva Salmeron, Juan Manuel 30 January 2013 (has links)
Technology such as television, computers, and video games are often in the line for reasons of why people lack physical activity and tend to gain weight and become obese. In the case of video games, with the advent of the so called “serious games initiative”, a new breed of video games have come into place. Such games are called “exergames” and they are intended to motivate the user to do physical activity. Although there is some evidence that some types of Exergames are more physically demanding than traditional sedentary games, there is also evidence that suggests that such games are not really providing the intensity of exert that is at the recommended levels for a daily exercise. Currently, most exergames have a passive approach. There is no real tracking of the players progress, there is no assessment of his/her level of exert, no contextual information, and there is no adaptability on the game itself to change the conditions of the game and prompt the desired physiological response on the player. In this thesis we present research work done towards the design and development of an architecture and related systems that support a shift in the exertion game paradigm. The contributions of this work are enablers in the design and development of exertion games with a strict serious game approach. Such games should have “exercising” as the primary goal, and a game engine that has been developed under this scheme should be aware of the exertion context of the player. The game should be aware of the level of exertion of the player and adapt the gaming context (in-game variables and exertion interface settings) so that the player can reach a predefined exertion rate as desired. To support such degree of adaptability in a multimedia, multimodal system, we have proposed a system architecture that lays down the general guidelines for the design and development of such systems.
167

A Portrait of Porta Portese

Yang, Amy Ya-Chih January 2009 (has links)
This thesis investigates an informally self-organized street market, Porta Portese, in Rome, Italy. As a response to the contemporary phenomenon of migration, of people and goods, Porta Portese reflects the city’s evolving urban, cultural and social dynamics under the impact of global forces. Based on fieldwork executed from 2007-2009, this thesis builds on the idea of scoring in an attempt to establish a framework of tangible notations, using mediums ranging from time-lapse photography to pattern mapping. The language of architecture is adapted to render visible the spatial dynamics in the fabrication of the market. Despite its lack of representation, Porta Portese leaves its mark as a layer of the invisible city of Rome. One can trace its terrain through palpable memories of a collective urban and cultural experience, for it transports ideas, images and values between different worlds based on universal understandings. Ultimately, this thesis advocates for an interpretive representation of places like Porta Portese as valuable urban spaces that celebrate and satisfy the needs of direct human experience. This is achieved through enabling the neglected voice of a place that can strike a resonating chord of dialogue amongst differences - and it all begins from a story about Porta Portese.
168

Factors Affecting Human Force Perception and Performance in Haptic-Enabled Virtual Environments

Zadeh, Mehrdad Hosseini January 2009 (has links)
Haptic technology enables computer users to touch and/or manipulate virtual objects in virtual environments (VEs). Similar to other human-in-the-loop applications, haptic applications require interactions between humans and computers. Thus, human-factors studies are required to recognize the limitations and capabilities of the user. This thesis establishes human-factors criteria to improve various haptic applications such as perception-based haptic compression techniques and haptic-enabled computer-aided design (CAD). Today, data compression plays a significant role in the transmission of haptic information since the efficient use of the available bandwidth is a concern. Most lossy haptic compression techniques rely on the limitations of human force perception, and this is used in the design of perception-based haptic compression techniques. Researchers have studied force perception when a user is in static interaction with a stationary object. This thesis focuses on cases where the human user and the object are in relative motion. The limitations of force perception are quantified using psychophysical methods, and the effects of several factors, including user hand velocity and sensory adaptation, are investigated. The results indicate that fewer haptic details need to be calculated or transmitted when the user's hand is in motion. In traditional CAD systems, users usually design virtual prototypes using a mouse via their vision system only, and it is difficult to design curved surfaces due to the number, shape, and position of the curves. Adding haptics to CAD systems enables users to explore and manipulate virtual objects using the sense of touch. In addition, human performance is important in CAD environments. To maintain the accuracy, active haptic manipulation of the user response can be incorporated in CAD applications. This thesis investigates the effect of forces on the accuracy of movement in VEs. The results indicate that factors such as the base force intensity and force increment/decrement can be incorporated in the control of users' movements in VEs. In other words, we can pull/push the users' hands by increasing/decreasing the force without the users being aware of it.
169

A Portrait of Porta Portese

Yang, Amy Ya-Chih January 2009 (has links)
This thesis investigates an informally self-organized street market, Porta Portese, in Rome, Italy. As a response to the contemporary phenomenon of migration, of people and goods, Porta Portese reflects the city’s evolving urban, cultural and social dynamics under the impact of global forces. Based on fieldwork executed from 2007-2009, this thesis builds on the idea of scoring in an attempt to establish a framework of tangible notations, using mediums ranging from time-lapse photography to pattern mapping. The language of architecture is adapted to render visible the spatial dynamics in the fabrication of the market. Despite its lack of representation, Porta Portese leaves its mark as a layer of the invisible city of Rome. One can trace its terrain through palpable memories of a collective urban and cultural experience, for it transports ideas, images and values between different worlds based on universal understandings. Ultimately, this thesis advocates for an interpretive representation of places like Porta Portese as valuable urban spaces that celebrate and satisfy the needs of direct human experience. This is achieved through enabling the neglected voice of a place that can strike a resonating chord of dialogue amongst differences - and it all begins from a story about Porta Portese.
170

Factors Affecting Human Force Perception and Performance in Haptic-Enabled Virtual Environments

Zadeh, Mehrdad Hosseini January 2009 (has links)
Haptic technology enables computer users to touch and/or manipulate virtual objects in virtual environments (VEs). Similar to other human-in-the-loop applications, haptic applications require interactions between humans and computers. Thus, human-factors studies are required to recognize the limitations and capabilities of the user. This thesis establishes human-factors criteria to improve various haptic applications such as perception-based haptic compression techniques and haptic-enabled computer-aided design (CAD). Today, data compression plays a significant role in the transmission of haptic information since the efficient use of the available bandwidth is a concern. Most lossy haptic compression techniques rely on the limitations of human force perception, and this is used in the design of perception-based haptic compression techniques. Researchers have studied force perception when a user is in static interaction with a stationary object. This thesis focuses on cases where the human user and the object are in relative motion. The limitations of force perception are quantified using psychophysical methods, and the effects of several factors, including user hand velocity and sensory adaptation, are investigated. The results indicate that fewer haptic details need to be calculated or transmitted when the user's hand is in motion. In traditional CAD systems, users usually design virtual prototypes using a mouse via their vision system only, and it is difficult to design curved surfaces due to the number, shape, and position of the curves. Adding haptics to CAD systems enables users to explore and manipulate virtual objects using the sense of touch. In addition, human performance is important in CAD environments. To maintain the accuracy, active haptic manipulation of the user response can be incorporated in CAD applications. This thesis investigates the effect of forces on the accuracy of movement in VEs. The results indicate that factors such as the base force intensity and force increment/decrement can be incorporated in the control of users' movements in VEs. In other words, we can pull/push the users' hands by increasing/decreasing the force without the users being aware of it.

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