A Simple Physically-Based 3D Liquids Surface Tracking Algorithm

Navier-Stokes-based methods have been used in computer graphics to simulate liquids, especially water. These physically based methods are computationally intensive, and require rendering the water surface at each step of the simulation process. The rendering of water surfaces requires knowing which 3D grid cells are crossed by the water’s surface, that is, tracking the surface across the cells is necessary. Solutions to water surface tracking and rendering problems exist in literature, but they are either too computationally intensive to be appropriate for real-time scenarios, as is the case of deformable implicit surfaces and ray-tracing, or too application-specific, as is the case of height-fields to simulate and render water mantles (e.g., lakes and oceans). This paper proposes a novel solution to water surface tracking that does not compromise the overall simulation performance. This approach differs from previous solutions in that it directly classifies and annotates the density of each 3D grid cell as either water, air, or water-air (i.e., water surface), opening the opportunity for easily reconstructing the water surface at an interactive frame rate.

Tangible Interfaces for Art Restoration

Few people experience art the way a restorer does: as a tactile, multi-dimensional and ever-changing object. The authors investigate a set of tools for the distributed analysis of artworks in physical and digital realms. Their work is based on observation of professional art restoration practice and rich data available through multi-spectral imaging. The article presents a multidisciplinary approach to develop interfaces usable by restorers, students and amateurs. Several interaction techniques were built using physical metaphors to navigate the layers of information revealed by multi-spectral imaging, prototyped using single- and multi-touch displays. The authors built modular systems to accommodate the technical needs and resources of various institutions and individuals, with the aim to make high-quality art diagnostics possible on different hardware platforms, as well as rich diagnostic and historic information about art available for education and research through a cohesive set of web-based tools instantiated in physical interfaces and public installations.

Rain Simulation in Dynamic Scenes

Rain is a complex phenomenon and its simulation is usually very costly. In this article, the authors propose a fully-GPU rain simulation based on the utilization of particle systems. The flexibility of CUDA allows the authors to include, aside from the rainfall simulation, a system for the detection and handling of the collisions of particles against the scenario. This detection system allows for the simulation of splashes at the same time. This system obtains a very high performance because of the hardware programming capabilities of CUDA.

On Not Being Able to Draw a Mousetrap

A hundred years ago officers entering the Royal Navy took an exam where they had to draw a mouse-trap. At the time there was much discussion, and some despair, about competence, and about teaching. For amateurs, drawing manuals provided instructions on how to render a still life in 3D, or draw a running figure, tasks that would now be effortless given current software. Today much debate about drawing, its purpose, and about ‘digital drawing’, and de-skilling. Graphics programs are designed for ‘realism’. But contemporary drawing looks in the opposite direction: into the processes of drawing; the expressive mark; and the structure and character of the line. Those who deal with the evolving gadgetry of digital drawing have had to contend both with unhelpful software, and with an art world that has yet to realise the scope of this new visual universe.

An Assistant Interface to Design and Produce a Pop-Up Card

This article describes an assistant interface to design and produce pop-up cards. A pop-up card is a piece of folded paper from which a three-dimensional structure pops up when opened. The authors propose an interface to assist the user in the design and production of a pop-up card. During the design process, the system examines whether the parts protrude from the card or whether the parts collide with one another when the card is closed. The user can concentrate on the design activity because the error occurrence and the error resolution are continuously fed to the user in real time. The authors demonstrate the features of their system by creating two pop-up card examples and perform an informal preliminary user study, showing that automatic protrusion and collision detection are effective in the design process.

Magnet Mail

Magnet Mail (MM) is a visualization system for emails based on a zoomable interface and on manipulation of objects. Users are able to search, analyze and understand relations among email messages as long as they provide searching keywords to do so, as well as interact with graphical objects in the display in a pro-active manner. The underlying concept is a magnet metaphor that relates user interaction, searching keywords and relations among emails. In this paper, the authors present a prototype that interacts with a mass-market email system and most of its graphical implementation relies on the Piccolo toolkit.

Organix

This paper presents a mechanism for generating visually appealing but also effective representations for document visualisation. The mechanism is based on an organic growth model which is driven by features of the object to be visualised. In the examples used, the authors focus on the visualisation of text documents, but the methods are readily transferable to other domains. They are also scaleable to documents of any size. The objective of this research is to build visual representations that enable the human visual system to efficiently and effectively recognise documents without the need for higher level cognitive processing. In particular, the authors want the user to be able to recognise similarities within sets of documents and to be able to easily discriminate between dissimilar objects.

World-in-Miniature Interaction for Complex Virtual Environments

Object occlusion is a major handicap for efficient interaction with 3D virtual environments. The well-known World in Miniature (WIM) metaphor partially solves this problem by providing an additional dynamic viewpoint through a hand-held miniature copy of the scene. However, letting the miniature show a replica of the whole scene makes the WIM metaphor suitable for only relatively simple scenes due to occlusion and level of scale issues. In this paper, the authors propose several algorithms to extend the idea behind the WIM to arbitrarily complex scenes. The main idea is to automatically decompose indoor scenes into a collection of cells that define potential extents of the miniature replica. This cell decomposition works well for general indoor scenes and allows for simple and efficient algorithms for preserving the visibility of potential targets inside the cell. The authors also discuss how to support interaction at multiple levels of scale by allowing the user to select the WIM size according to the accuracy required for accomplishing the task.

Accurate Infrared Tracking System for Immersive Virtual Environments

In large-scale immersive virtual reality (VR) environments, such as a CAVE, one of the most common problems is tracking the position of the user’s head while he or she is immersed in this environment to reflect perspective changes in the synthetic stereoscopic images. In this paper, the authors describe the theoretical foundations and engineering approach adopted in the development of an infrared-optical tracking system designed for large scale immersive Virtual Environments (VE) or Augmented Reality (AR) settings. The system is capable of tracking independent retro-reflective markers arranged in a 3D structure in real time, recovering all possible 6DOF. These artefacts can be adjusted to the user’s stereo glasses to track his or her head while immersed or used as a 3D input device for rich human-computer interaction (HCI). The hardware configuration consists of 4 shutter-synchronized cameras attached with band-pass infrared filters and illuminated by infrared array-emitters. Pilot lab results have shown a latency of 40 ms when simultaneously tracking the pose of two artefacts with 4 infrared markers, achieving a frame-rate of 24.80 fps and showing a mean accuracy of 0.93mm/0.51º and a mean precision of 0.19mm/0.04º, respectively, in overall translation/rotation, fulfilling the requirements initially defined.

User Experiences and Differences in Viewing Architectural Images with Various Interfaces

This paper proposes an empirical approach to the visualization phase of architectural images, employing established concepts, methodologies, and measurement techniques found in media psychology and user-centered studies. The paper proposes a human-centered approach for conceptualizing visualization technologies and evaluating the quality concept of images to simulate a satisfactory architectural experience. The authors use psychophysiological measures to capture the affective component of image quality experience facilitated by different displays, including immersive and nonimmersive displays. These types of visualizations are important for empirically evaluating the experiential aspects of an architectural space and other types of images.