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Dive into the research topics where Georgios Nikolakis is active.

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Featured researches published by Georgios Nikolakis.


IEEE Transactions on Neural Systems and Rehabilitation Engineering | 2004

Design and implementation of haptic virtual environments for the training of the visually impaired

Dimitrios Tzovaras; Georgios Nikolakis; Georgios Fergadis; Stratos Malasiotis; Modestos Stavrakis

This paper presents a haptic virtual reality (VR) tool developed for the training of the visually impaired. The proposed approach focuses on the development of a highly interactive and extensible haptic VR training system (the ENORASI VR training system) that allows visually impaired, to study and interact with various virtual objects in specially designed virtual environments, while allowing designers to produce and customize these configurations. Based on the system prototype and the use of the CyberGrasp haptic device, a number of custom applications have been developed. An efficient collision detection algorithm is also introduced, by extending the proximity query package (PQP) algorithm to handle five points of contact (a case studied with the use of CyberGrasp). Two test categories were identified and corresponding tests were developed for each category. The training scenarios include: object recognition and manipulation and cane simulation, used for performing realistic navigation tasks. Twenty-six blind persons conducted the tests and the evaluation results have shown the degree of acceptance of the technology and the feasibility of the proposed approach.


IEEE MultiMedia | 2007

Haptic Rendering of Visual Data for the Visually Impaired

Konstantinos Moustakas; Georgios Nikolakis; Konstantinos Kostopoulos; Dimitrios Tzovaras; Michael G. Strintzis

We introduce a force-field haptic rendering method for converting visual data to haptic data. The method includes a novel framework to convert specialized 3D map models into force fields. We generate the final force fields by using structure from motion and implicit surface approximation algorithms. Visually impaired people then can learn to navigate with these maps, using off-the-shelf haptic


digital television conference | 2007

Haptic Access to Conventional 2D Maps for the Visually Impaired

Konstantinos Kostopoulos; Konstantinos Moustakas; Dimitrios Tzovaras; Georgios Nikolakis

This paper describes a framework of map image analysis and presentation of the semantic information to blind users using alternative modalities (i.e. haptics and audio). The resulting haptic-audio representation of the map is used by the blind for navigation and path planning purposes. The proposed framework utilizes novel algorithms for the segmentation of the map images using morphological filters that are able to provide indexed information on both the street network structure and the positions of the street names in the map. Next, off-the-shelf OCR and TTS algorithms are utilized to convert the visual information of the street names into audio messages. Finally, a grooved-line-map representation of the map network is generated and the blind users are able to investigate it using a haptic device. While navigating, audio messages are displayed providing information about the current position of the user (e.g. street name, crossroad notification e.t.c). Experimental results illustrate that the proposed system is considered very promising for the blind users and has been reported to be a very fast means of generating maps for the blind when compared to other traditional methods like Braille images.


ubiquitous computing | 2009

Interactive mixed reality white cane simulation for the training of the blind and the visually impaired

Dimitrios Tzovaras; Konstantinos Moustakas; Georgios Nikolakis; Michael G. Strintzis

This paper presents a mixed reality tool developed for the training of the visually impaired based on haptic and auditory feedback. The proposed approach focuses on the development of a highly interactive and extensible Haptic Mixed Reality training system that allows visually impaired to navigate into real size Virtual Reality environments. The system is based on the use of the CyberGrasp™ haptic device. An efficient collision detection algorithm based on superquadrics is also integrated into the system so as to allow real time collision detection in complex environments. A set of evaluation tests is designed in order to identify the importance of haptic, auditory and multimodal feedback and to compare the MR cane against the existing Virtual Reality cane simulation system.


ieee virtual reality conference | 2005

A geometry education haptic VR application based on a new virtual hand representation

Konstantinos Moustakas; Georgios Nikolakis; Dimitrios Tzovaras; Michael G. Strintzis

The ability to physically change properties of real objects used in augmented reality (AR) applications is limited. Geometrical properties (shape, size) and appearance (color, texture) of a real object remain unchanged during a single application run. However, an AR system can be used to provide a virtual texture for the real object. The texture can be changed dynamically based on user interactions. The developed AR system includes two components, the 3D Table and the Texture Painter. The 3D Table is a table where real objects are placed. The tabletop is used as a projection surface, making it possible to add a context to the real object. The Texture Painter makes it possible to paint on the real object, using a real brush and virtual ink (texture). ARToolkit markers are placed on the 3D Table tabletop to augment the environment with the virtual objects. Markers are either physical (printouts on the tabletop) or virtual (projections). The scene is recorded with a camera and the composed video is projected in real time. The projection shows a virtual environment, real objects painted with virtual ink, and virtual objects positioned where real or virtual ARToolkit markers are placed. The developed system is used in architectural design applications where, due to the different qualities of real architectural models and rendered architectural models, real models are still used. The system was tested at the Academy of Fine Arts in Vienna where it is used as a support tool for architecture students.The present paper describes an enhanced haptic virtual reality application for geometry education. The proposed application allows the user to create and edit a scene that consists of three-dimensional geometrical objects in order to form and solve complex geometrical problems. The core of the proposed scheme is based on a novel interference detection algorithm, which utilizes implicit surfaces, such as superquadrics, and their analytical description to speed up collision detection between the virtual hand and the virtual environment. Intersection tests are executed utilizing the implicit analytical formulae of the superquadrics. Experimental results demonstrate the high applicability of the proposed application and the huge gain in speed of the proposed collision detection approach when compared to state of the art methods.


hellenic conference on artificial intelligence | 2004

A Mixed Reality Learning Environment for Geometry Education

Georgios Nikolakis; George Fergadis; Dimitrios Tzovaras; Michael G. Strintzis

This paper presents a mixed reality environment for geometry education. The proposed system consists of three main sub-components: The Geometry construction agent, which allows users to create objects in the 3D scene, a Collision Detection algorithm, which calculates the collisions between the virtual hand and the dynamical geometrical objects and the haptic interaction agent which is responsible for the haptic feedback returned to the user. The user can perform actions in the virtual environment using a haptic glove and create a scene out of geometrical objects. Stereoscopic view is supported and actions are visualized on a large screen so that many users can observe the actions. The system has been evaluated in secondary schools in Thessaloniki, Greece and the results have shown that users consider it very satisfactory in terms of providing a more efficient learning approach.


symposium on haptic interfaces for virtual environment and teleoperator systems | 2005

Haptic feedback using an efficient superquadric based collision detection method

Konstantinos Moustakas; Georgios Nikolakis; Dimitrios Koutsonanos; Dimitrios Tzovaras; Michael G. Strintzis

The present paper proposes an efficient collision detection algorithm suitable for use in haptic applications. The method exploits the fact that the virtual hand can be modelled once using superquadrics and then be used in a variety of applications. The proposed scheme is seen to be much faster and realistic when compared to standard mesh-based approaches.


International Journal of Architectural Computing | 2007

Simulating the Use of Ancient Technology Works Using Advanced Virtual Reality Technologies

Konstantinos Moustakas; Dimitrios Tzovaras; Georgios Nikolakis

This paper introduces a novel framework for the modeling and interactive simulation of ancient Greek technology works with the use of advanced virtual reality technologies. A novel algorithm is introduced for the realistic and efficient resolution of collisions that is based on an advanced collision detection approach that can also calculate in real-time the force that should be fed back to the user using a haptic device. Thus, the user is capable of manipulating the scene objects in the environment using haptic devices to simulate the sense of touch and stereoscopic imaging so as to be immersed in the virtual environment. Moreover, the virtual hand that simulates the users hand is modeled using superquadrics so as to further increase the speed of the simulation and the fidelity of the force feedback. Extended evaluation of the system has been performed with visitors of the Science Center and Technology Museum of Thessaloniki.


artificial intelligence applications and innovations | 2006

3D content-based search using sketches

Konstantinos Moustakas; Georgios Nikolakis; Dimitrios Tzovaras; Sébastien Carbini; Olivier Bernier; Jean-Emmanuel Viallet

The present work presents a novel framework for 3D content-based search and retrieval. On contrary to most state-of-the-art approaches, the query model can be not only an existing object from a database but also a model manually generated by the user using sketches. In the context of the proposed framework, three interfaces to the sketch-based 3D search application were tested and comparative results were extracted according to usability and efficiency criteria.


artificial intelligence applications and innovations | 2006

Mixed Reality Cane Simulation

Dimitrios Tzovaras; Konstantinos Moustakas; Georgios Nikolakis; Michael G. Strintzis

In the present paper a mixed reality cane simulation environment is presented that allows blind people to navigate in virtual worlds. The application is based on the combination of a real cane with a haptic force feedback system. The users can therefore handle the cane in a natural way and perceive realistic force feedback from virtual objects. Experimental results demonstrate the advantages of the MR approach when compared to the VR one.

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Dive into the Georgios Nikolakis's collaboration.

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Dimitrios Tzovaras

Information Technology Institute

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Michael G. Strintzis

Aristotle University of Thessaloniki

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Dimitrios Koutsonanos

Aristotle University of Thessaloniki

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Konstantinos Kostopoulos

Aristotle University of Thessaloniki

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Ioannis Marras

Aristotle University of Thessaloniki

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Sotiris Malassiotis

Aristotle University of Thessaloniki

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Petros Daras

Information Technology Institute

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