Helmuth Trefftz

Parallelizing AES on multicores and GPUs

The AES block cipher cryptographic algorithm is widely used and it is resource intensive. An existing sequential open source implementation of the algorithm was parallelized on multi-core microprocessors and GPUs. Performance results are presented.

Sharing viewpoints in collaborative virtual environments

We explore to what degree shared viewpoints in three-dimensional collaborative virtual environments enable effective collaboration. We apply research on shared viewpoints and telepointers to 3D environments. A lightweight Java-based tool for creating collaborative virtual environments was developed and used in the study. The system is realized as an application framework that can be customized to develop new applications. We conducted a series of experiments to assess the effectiveness of shared viewpoints on two simple tasks. Control groups were provided with telepointers. Experimental groups were provided with telepointers and shared views. The results indicate that for participants with access to both tools, shared views are preferred over telepointers for tasks involving joint exploration of either the environment or some object of common interest.

Collaborative Virtual Environments for Teaching Physics

Eafit University created a Telepresence application for distance education. It supports bi-directional audio and video and a shared virtual environment that allows the instructor and students to manipulate virtual objects in a collaborative manner, thereby reinforcing the learning process. In this paper we report the experience of creating new contents and deploying the tool in a Physics course at Universidad del Quindio. The tool was improved an extended in order to include new functionality and make it easier for development teams to create new content. Teaching for Understanding was used as pedagogical framework for course creation and also as a guide to develop the interviews that were used to capture user’s perceptions and to asses the improvements in the learning process. The results showed that the use of the tool had a positive impact on the students’ understanding of the topics at hand.

Distance Interaction in Education Processes using a Telepresence Tool

Distance interaction among educational communities is becoming increasingly important. Courses and talks are shared among institutions and individuals who are located in different places. The Telepresence tool, developed by Eafit and Universidad del Quindio, permits course sharing among the institutions. Instructors from one institution can teach students of the other one, thereby sharing the positive features of each course. In this paper, we present the recent improvements of the Telepresence tool. We also report on the use of the tool in a Multi-Variable Calculus course, designed in accordance to the Teaching for Understanding (TFU) pedagogical framework..

Telepresence support for synchronous distance

This paper describes a telepresence application that combines bi-directional video, audio and a shared virtual environment as means to support synchronous distance education sessions.In order to validate the effectiveness of the tool, it was used in several courses at our University. Students were divided into an experimental group -- using the tool in a simulated distance learning environment -- and a control group -- receiving traditional face-to-face lectures --. The results show that the use of the telepresence application, hand in hand with an appropriate pedagogical framework, lead the students in the distance education sessions to reach at least the same levels of understanding, and sometimes even better, than those attained by students in the face-to-face sessions.We are offering the telepresence application to other education institutions in our country, with the hope that it will allow students in regions isolated by the war or by the lack of infrastructure to have access to better education, both at school and university levels.

Message caching for local and global resource optimization in shared virtual environments

The use of Shared Virtual Environments is growing in areas such as multi-player video games, military and industrial training, and collaborative design and engineering. As a result, different mixes of computing power and graphics capabilities of the participating computers arise naturally as the variety of people/organizations sharing a virtual environment grows. This paper presents an adaptive mechanism to reduce bandwidth usage and to optimize the use of computing resources of heterogeneous computers mixes utilized in a shared virtual environment. The mechanism is based on caching of both outgoing- and incoming-messages. We also report the results of implementing the proposed scheme in a simple shared virtual environment.

Distance Education and Distributed Virtual Environments

The possible applications of Distributed Virtual Environments to support Distance Education are being explored. A first experience with IRC (Internet Relay Chat) is described.

Collaborative networked virtual surgical simulators cnvss implementing hybrid client-server architecture: Factors affecting collaborative performance

Currently, surgical skills teaching in medical schools and hospitals is changing, requiring the development of new tools to focus on (i) the importance of the mentor’s role, (ii) teamwork skills training, and (iii) remote training support. Collaborative Networked Virtual Surgical Simulators (CNVSS) allow collaborative training of surgical procedures where remotely located users with different surgical roles can take part in the training session. To provide successful training involving good collaborative performance, CNVSS should guarantee synchronicity in time of the surgical scene viewed by each user and a quick response time which are affected by factors such as users’ machine capabilities and network conditions. To the best of our knowledge, the impact of these factors on the performance of CNVSS implementing hybrid client–server architecture has not been evaluated. In this paper the development of a CNVSS implementing a hybrid client–server architecture and two statistical designs of experiments (DOE) is described by using (i) a fractional factorial DOE and (ii) a central composite DOE, to determine the most influential factors and how these factors affect the collaboration in a CNVSS. From the results obtained, it was concluded that packet loss, bandwidth, and delay have a larger effect on the consistency of the shared virtual environment, whereas bandwidth, server machine capabilities, and delay and interaction between factors bandwidth and packet loss have a larger effect on the time difference and number of errors of the collaborative task.

Design and Implementation of a Low-Cost Projected Virtual Reality System to Support Learning Processes

Virtual Reality technologies have been successfully incorporated into the learning processes and potential new applications in education are explored continuously. We found that one of the difficulties to popularize its use in the educational context, in countries with emerging and developing economies, is the cost of hardware required to generate satisfactory immersive experience. In this work we considered virtual reality from the perspective of human-computer interaction to support learning processes. The characteristics of low-cost projected virtual reality system (PVR) proposed, combines study and integration of available technology solutions, the development of an image synchronization routine that enables the use of a single video projector and the design of a printable pattern that preserve the state of polarization on the projection screen.

Design and Usability Evaluation of a Multi-input Interface in an idTV Environment

In recent years, and considering the rise of Interactive Digital Television (idTV), it has been great interest in the design of applications and services for this platform. However, the success of these applications largely depends on the ease of use and how users interact with them. For this reason, we have explored different interfaces and modes of interaction to improve the user experience with these applications in comparison with the traditional Remote-Control (RC). This article presents an interaction with idTV applications using multiple input control interfaces with different modes of interaction such as touch buttons, gesture recognition, voice recognition, and recognition of movements. These modes of interaction were validated through usability testing using a model of quasi-experimental evaluation of three dimensions, where each dimension represents respectively: users, tasks and control interfaces. As a result of the qualitative and quantitative assessments, we performed an analysis of possible improvements in the usability of a particular application of idTV. The results showed few differences between one multi-input control interface and one RC in tasks the user was familiar with, on the opposite, significant differences were found in performing tasks involving greater user interaction, such as the text input or navigation between menus.