Pascal Guitton

A camera-based interface for interaction with mobile handheld computers

Recent advances in mobile computing allow the users to deal with 3D interactive graphics on handheld computers. Although the computing resources and screen resolutions grow steadily, user interfaces for handheld computers do not change significantly. Consequently, we designed a new 3-DOF interface adapted to the characteristics of handheld computers. This interface tracks the movement of a target that the user holds behind the screen by analyzing the video stream of the handheld computer camera. The position of the target is directly inferred from the color-codes that are printed on it using an efficient algorithm. The users can easily interact in real-time in a mobile setting. The visualization of the data is good as the target does not occlude the screen and the interaction techniques are not dependent on the orientation of the handheld computer. We used the interface in several test applications for the visualization of large images such as maps, the manipulation of 3D models, and the navigation in 3D scenes. This new interface favors the development of 2D and 3D interactive applications on handheld computers.

Navidget for Easy 3D Camera Positioning from 2D Inputs

Navidget is a new interaction technique for camera positioning in 3D environments. This technique derives from the point-of-interest (POI) approaches where the endpoint of a trajectory is selected for smooth camera motions. Unlike the existing POI techniques, Navidget does not attempt to automatically estimate where and how the user wants to move. Instead, it provides good feedback and control for fast and easy interactive camera positioning. Navidget can also be useful for distant inspection when used with a preview window. This new 3D User interface is totally based on 2D inputs. As a result, it is appropriate for a wide variety of visualization systems, from small handheld devices to large interactive displays. A user study on TabletPC shows that the usability of Navidget is very good for both expert and novice users. This new technique is more appropriate than the conventional 3D viewer interfaces for some camera positioning tasks in 3D environments.

Adaptive hierarchical RBF interpolation for creating smooth digital elevation models

This paper presents a fast algorithm for smooth digital elevation model interpolation and approximation from scattered elevation data. The global surface is reconstructed by subdividing it into overlapping local subdomains using a perfectly balanced binary tree. In each tree leaf, a smooth local surface is reconstructed using radial basis functions. Finally a hierarchical blending is done to create the final C¹-continuous surface using a family of functions called Partition of Unity. We present two terrain data sets and show that our method is robust since the number of data points in the Partition of Unity blending areas is explicitly specified.

Toponym Recognition in Scanned Color Topographic Maps

Topographic paper maps are a common support for geographical information. In the field of document analysis of this kind of support, this paper proposes an automatic approach to extract and recognize toponyms. We present a technique based on image segmentation and connected component processing. Different filtering stages ensure the consistency of plausible characters and strings. Detected text areas are used to feed an OCR software and the recognized words are analyzed and corrected. The main advantage of our technique is that no assumption is made about the character font, size or orientation. Experimental results obtained are encouraging in term of recognition efficiency.

The Use of Virtual Reality for Episodic Memory Assessment Effects of Active Navigation

Episodic memory was assessed using Virtual Reality (VR). Forty-four (44) subjects visualized a target virtual apartment containing specific objects in each room. Then they visualized a second virtual apartment comprised of specific objects and objects shared by the two apartments. Subjects navigated in the virtual apartments in one of the following two conditions: active and passive. Four main episodic memory components were scored from the VR exposures: (1) learning effect; (2) active forgetting effect; (3) strategies at encoding and at retrieval; and (4) false recognitions (FRs). The effect of navigation mode (active vs. passive) on each memory component was examined. Active subjects had better learning and retrieval (recognition hits) performances compared to passive subjects. A beneficial effect of active navigation was also observed on the source-based FR rates. Active subjects made fewer source-based FRs compared to passive subjects. These overall results for the effect of active navigation are discussed in terms of the distinction between item-specific and relational processing.

Navidget for 3D interaction: Camera positioning and further uses

This paper presents an extended version of Navidget. Navidget is a new interaction technique for camera positioning in 3D environments. This technique derives from the point-of-interest (POI) approaches where the endpoint of a trajectory is selected for smooth camera motions. Unlike the existing POI techniques, Navidget does not attempt to automatically estimate where and how the user wants to move. Instead, it provides good feedback and control for fast and easy interactive camera positioning. Navidget can also be useful for distant inspection when used with a preview window. This new 3D user interface is totally based on 2D inputs. As a result, it is appropriate for a wide variety of visualization systems, from small handheld devices to large interactive displays. A user study on TabletPC shows that the usability of Navidget is very good for both expert and novice users. This new technique is more appropriate than the conventional 3D viewer interfaces in numerous 3D camera positioning tasks. Apart from these tasks, the Navidget approach can be useful for further purposes such as collaborative work and animation.

The interaction table: a new input device designed for interaction in immersive large display environments

Large display systems such as Reality Centers or Powerwalls, allow several users to be immersed in a virtual environment while being located in the same physical space. The characteristics of such systems induce new problems and new constraints as far as it concerns the interaction. According to the lack of input devices well adapted to large displays, we are developing a new interactor: The Interaction Table. This device, composed of a movable tray fixed on a pillar, offers 6 DOFs and uses both isotonic and isometric information. The table top offers a 2D plane on which the position of a pen can be recovered. Many 2D and 3D interaction techniques can be used to accomplish the different interaction tasks (navigation, manipulation, selection, system control) dealing with different space ranges. The design of the Interaction Table makes it accurate and easy to use without any effort. Its auto-supported aspect makes it a non constraining tool, which can be shared by all co-located users. We illustrate the utility of the Interaction Table through a real application of 3D geomarketing.

Interactive Generation and Modification of Cutaway Illustrations for Polygonal Models

We present a system for creating appealing illustrative cutaway renderings. This system bases on simple sketch-based interfaces and stylized rendering techniques for the study of elaborate 3D models. Since interactive visualization technology found its way to the general public, there is a demand for novel interaction techniques that allow easy exploration of the displayed illustrations. Hence, our system lets users create individual cutaway views to focus on hidden objects. At the same time, important contextual information is emphasized by illustrative rendering techniques.

A New Efficient Wave Model for Maritime Training Simulator

The market for maritime training simulators is as important as the market for aeronautical training simulators. Many maritime accidents are caused by piloting errors in critical situations. Such situations are usually due to the environment (waves and streams). Hence, the main challenge of a maritime simulator is to simulate this environment as accurately as possible and, more precisely, to simulate ocean waves. Nowadays, two kinds of wave simulation theories are being presented. Firstly, accurate models are being created by physicists, while in computer graphics, researchers are putting forward some simpler physically-based models in order to produce static photorealistic images. This paper describes a new, efficient, real-time model of wave propagation and shows its integration in a real maritime simulator.

Age and active navigation effects on episodic memory: A virtual reality study

We investigated the navigation-related age effects on learning, proactive interference semantic clustering, recognition hits, and false recognitions in a naturalistic situation using a virtual apartment-based task. We also examined the neuropsychological correlates (executive functioning [EF] and episodic memory) of navigation-related age effects on memory. Younger and older adults either actively navigated or passively followed the computer-guided tour of an apartment. The results indicated that active navigation increased recognition hits compared with passive navigation, but it did not influence other memory measures (learning, proactive interference, and semantic clustering) to a similar extent in either age group. Furthermore, active navigation helped to reduce false recognitions in younger adults but increased those made by older adults. This differential effect of active navigation for younger and older adults was accounted for by EF score. Like for the subject-performed task effects, the effects from the navigation manipulation were well accounted for by item-specific/relational processing distinction, and they were also consistent with a source monitoring deficit in older adults.