Jean-François Lapointe

A comparative study of four input devices for desktop virtual walkthroughs

This paper presents the results of an experiment measuring the effect of four different input devices on overall task performance for desktop virtual walkthroughs. The input devices tested are: a keyboard, a mouse, a joystick and a gamepad. The results indicate that the participants completed the tasks in significantly less time and distance travelled with the mouse than with the three other input devices. The use of the mouse also significantly reduced the number of collisions, while the use of the gamepad resulted in significantly more collisions.

On-screen laser spot detection for large display interaction

Laser pointer based interfaces present an interesting alternative for interaction with large displays such as those provided by video projection systems. In order to operate correctly, such systems need to quickly and reliably detect the on-screen laser spot generated by the pointer. This paper describes a fast algorithm for real-time laser spot tracking and presents some performance results.

Effects of joystick mapping and field-of-view on human performance in virtual walkthroughs

Virtual environments are increasingly used to visit virtual mockups of proposed buildings or virtualized models of real sites or buildings. This paper presents the results of a human-machine interaction experiment aimed at measuring the effects of the real field-of-view (FOV) and of the use of a third joystick axis on human performance for navigation in virtual walkthroughs in a closed-space environment. The results indicate that neither the real FOV nor the third joystick axis significantly affect performance. There is however a perceived increase of immersion with the larger real FOV, and an added freedom of movement when a third axis of movement is mapped onto the joystick.

On the digital reconstruction and interactive presentation of heritage sites through time

Virtual time travel from existing remains of a heritage site to its previous states and original condition is an educational and interesting experience and can provide better understanding of history. However, digitally reconstructing non-existing objects is a challenge. The interaction and navigation within virtual 4D worlds (adding time to 3D worlds) is also problematical due to the time dimension. In this paper we developed an approach to modelling of heritage sites that has undergone changes over the years. The method creates independent models from different types of data, such as frescos and paintings, drawings, old photos, historic descriptions, and digitization of remains, then assembles and integrates these models for an interactive presentation. Several research issues had to be addressed: (1) Modelling from frescos and drawings with incorrect perspective, (2) modelling from paintings and old photos including fine geometric details from shading (3) colouring models from old photos and drawings to match the colours of existing elements, (4) the seamless and accurate integration of models created independently from different sets of data, and (5) the creation of intuitive interactive presentation that combines all the models and other useful information. We provide contributions to these issues, including our own advanced model viewer, and apply them to modelling of: destroyed Haida house of Chief Weah (Masset, Canada), the demolished and partially relocated Rideau Chapel (Ottawa, Canada), and the Stenico castle (Trentino, Italy) which undergone many changes over several centuries. Each of these diverse examples illustrates different approach for reconstructing heritage sites that changed through time.

Digital reconstruction and 4D presentation through time

Virtual time travel transforming the existing remains of a heritage site to its original condition has value for education and cultural understanding. However, digitally reconstructing objects which no longer exist is a challenge. Interaction and navigation within virtual 4D worlds (adding time to 3D worlds) is also problematic due to imprecise understanding of the time dimension. In this project we developed an approach to 3D modeling of sites that have undergone changes over the years. The method creates independent models from different types of data, such as frescoes, paintings, drawings, old photos, historic documents, and digitized remains. The models are assembled and integrated for a 4D interactive presentation. Several research issues have been addressed: (1) Modeling from frescoes and drawings with incorrect perspective, (2) modeling from paintings and old photos including fine geometric details from shading (3) coloring models from old photos and drawings to match existing elements, (4) creation of models by seamless and accurate integration of data obtained from independent sources, and (5) the creation of intuitive interactive presentations that link the models with other multimedia components and information related to the history of the site. We will describe contributions to these issues, including our own advanced model viewer [Dem ], and apply them to modeling heritage sites such as Venice which appeared in paintings by Canaletto, Bernardo Bellotto, and Francesco Guardi, and many 19th century photos. Canalettos paintings have been used to measure the subsidence of Venice [Camuffo and Sturaro 2003].

An auto-calibrated laser-pointing interface for large screen displays

Most of the current laser pointing interfaces use a vision based approach, which requires camera calibration. This paper presents the use of a planar homography-based auto-calibrated technique to eliminate the camera calibration step, thus simplifying the setup process. The system performance of a user interface implemented with this technique is then analyzed in details.

Towards automatic modeling of monuments and towers

Three-dimensional modeling from images, when carried out entirely by a human, can be time consuming and impractical for large-scale projects. On the other hand, full automation may be unachievable or not accurate enough for many applications such as culture heritage documentation. In addition, three-dimensional modeling from images, particularly fully automated methods, requires the extraction of features, such as corners, and needs them to appear in multiple images. However, in practical situations those features are not always available, sometimes not even in a single image, due to occlusions or lack of texture on the surface. Taking closely separated images or optimally designing view locations can preclude some occlusions. However, taking such images is often not practical and we are left with small number of images that do not properly cover every surface or corner. The approach presented in this paper uses both interactive and automatic techniques, each where it is best suited, to accurately and completely model monuments and towers. It particularly focuses on automating the construction of unmarked surfaces such as columns, arches, and blocks from minimum available clues. It also extracts the occluded or invisible corners from existing ones. Many examples, such as Arc de Triomphe in Paris, Florences St. John baptistery at Santa Maria del Fiori Cathedral, and other monuments and towers from around the world are completely modeled from a small number of images taken by tourists.

Comparison of Viewpoint Orientation Techniques for Desktop Virtual Walkthroughs

This paper presents the results of a formal experiment that evaluated three viewpoint orientation techniques for desktop virtual walkthroughs. The results suggest that the use of either velocity or position control techniques for viewpoint orientation does not have a large effect on both travel time and distance for virtual walkthroughs. These results are useful for designers of desktop interactive 3D environments.

Learning and Performance Support - Personalization Through Personal Assistant Technology

Personalization is important for online learning due to the ever changing needs of online learners and because of its potential to reach a wide variety of users. This paper describes the results of a literature review about the personalization of online learning systems. It also describes results of user studies of the prototype of a learning and performance support (LPSS) platform developed at the National Research Council of Canada. Main findings are that personalized learning systems can enhance learning effectiveness and motivate learners, and that learners are looking for ways to better explore their learning context through social network.

A comparative study of three bimanual travel techniques for desktop virtual walkthroughs

This paper presents the results of a formal experiment that compared three bimanual travel techniques for desktop virtual walkthroughs, each having a different number of degrees of freedom (DOF) for the control interface. When compared in a primed search task, results indicate that the use of a 4-DOF interface with integrated pitch control provides a more realistic travel experience by allowing full visual exploration around the scene, while slightly increasing completion time when compared to the use of a 2-DOF or 3-DOF interface. The evaluation method developed here could be used to conduct further experimentation to explore other desktop travel techniques and/or other types of virtual environments.