Topological Sound Propagation with Reverberation Graphs

International audienceReverberation graphs is a novel approach to estimate global soundpressure decay and auralize corresponding reverberation effects in interactive virtual environments. We use a 3D model to represent the geometry of the environment explicitly, and we subdivide it into a series of coupled spaces connected by portals. Off-line geometrical-acoustics techniques are used to precompute transport operators, which encode pressure decay characteristics within each space and between coupling interfaces. At run-time, during an interactive simulation, we traverse the adjacency graph corresponding to the spatial subdivision of the environment. We combine transport operators along different sound propagation routes to estimate the pressure decay envelopes from sources to the listener. Our approach compares well with off-line geometrical techniques, but computes reverberation decay envelopes at interactive rates, ranging from 12 to 100 Hz. We propose a scalable artificial reverberator that uses these decay envelopes to auralize reverberation effects, including room coupling. Our complete system can render as many as 30 simultaneous sources in large dynamic virtual environments

CoronaSurveys: Using Surveys with Indirect Reporting to Estimate the Incidence and Evolution of Epidemics

The world is suffering from a pandemic called COVID-19, caused by the SARS-CoV-2 virus. National governments have problems evaluating the reach of the epidemic, due to having limited resources and tests at their disposal. This problem is especially acute in low and middle-income countries (LMICs). Hence, any simple, cheap and flexible means of evaluating the incidence and evolution of the epidemic in a given country with a reasonable level of accuracy is useful. In this paper, we propose a technique based on (anonymous) surveys in which participants report on the health status of their contacts. This indirect reporting technique, known in the literature as network scale-up method, preserves the privacy of the participants and their contacts, and collects information from a larger fraction of the population (as compared to individual surveys). This technique has been deployed in the CoronaSurveys project, which has been collecting reports for the COVID-19 pandemic for more than two months. Results obtained by CoronaSurveys show the power and flexibility of the approach, suggesting that it could be an inexpensive and powerful tool for LMICs.Comment: Presented at The KDD Workshop on Humanitarian Mapping, San Diego, California USA, August 24, 202

Stereoscopic non-photorealistic rendering

Zsfassung in dt. SpracheThe use of stereoscopy in fine arts enabled artists to create paintings and drawings that could detach from the flat surfaces they were laid on and float directly in front of the observer's eyes, opening a whole new world of possibilities for artistic experimentation. In the digital era, abundant computational methods have been developed to create monoscopic images that resemble artwork, using as an input either 3D models or images. Despite the high availability of such algorithms, hardly any research has been done so far in the area of artistic stereoscopic rendering from real images. The work presented in this dissertation provides a stepping stone in the direction of combining computer graphics and vision techniques to form novel image-based stereoscopic Non-Photorealistic Rendering algorithms. These algorithms can be used to transform photographic stereoscopic images into pairs of pictures that resemble stereoscopic drawings, cartoons or paintings.Furthermore, the artistic-looking stereoscopic image pairs generated using our algorithms provide a basis over which a set of interactive methods and tools are built to enhance the experience of viewers. The novel algorithms presented in this work set the foundation to harnessing stereoscopy as an artistic medium within the context of image-based computer graphics and vision, and their results may find utility in the game, media or film industries.13

Stereoscopic Painting with Varying Levels of Detail

We present an algorithm for generating automatically stereoscopic paintings with varying levels of detail. We describe our interactive system built around the algorithm to enable users to adjust the level of detail of the painting. In this context of interactivity we have modified our stereo painting algorithm, presented in previous work, in order to explore the idea of user-driven artistic level-of-detail selection and display. In particular, a stereo painting is composed by two canvases, one for each eye. These canvases contain multiple refining coarseto -fine layers of brush strokes that compose the final painting. In past research, the underlying coarser layers are obscured and function only as the basis to progressively build the finer painting layers. In contrast, our interactive stereo viewing system enables the user to selectively toggle the visibility of finer strokes to reveal coarser representations of the artwork

Parameterized sketches from stereo images

In this paper we present an algorithm to automatically generate sketches from stereo image pairs. Stereo analysis is initially performed on the input stereo pair to estimate a dense depth map. An Edge Combination image is computed by localising object contour edges, as indicated by the depth map, within the intensity reference image. We then approximate these pixel-represented contours by devising a new parametric curve fitting algorithm. The algorithm successfully recovers a minimum number of control points required to fit a Bézier curve onto the pixel-edge dataset in the Edge Combination image. Experiments demonstrate how the Edge Combination algorithm, used for dominant edge extraction, can be combined with a curve fitting algorithm to automatically provide parameterized artistic sketches or concept drawings of a real scene

Parameterized Sketches from Stereo Images

ABSTRACT In this paper we present an algorithm to automatically generate sketches from stereo image pairs. Stereo analysis is initially performed on the input stereo pair to estimate a dense depth map. An Edge Combination image is computed by localising object contour edges, as indicated by the depth map, within the intensity reference image. We then approximate these pixel-represented contours by devising a new parametric curve fitting algorithm. The algorithm successfully recovers a minimum number of control points required to fit a Bézier curve onto the pixel-edge dataset in the Edge Combination image. Experiments demonstrate how the Edge Combination algorithm, used for dominant edge extraction, can be combined with a curve fitting algorithm to automatically provide parameterized artistic sketches or concept drawings of a real scene

A Psychophysical Study of Fixation Behavior in a Computer Game

Prediction of gaze behavior in gaming environments can be a tremendously useful asset to game designers, enabling them to improve gameplay, selectively increase visual fidelity, and optimize the distribution of computing resources. The use of saliency maps is currently being advocated as the method of choice for predicting visual attention, crucially under the assumption that no specific task is present. This is achieved by analyzing images for low-level features such as motion, contrast, luminance, etc. However, the majority of computer games are designed to be easily understood and pose a task readily apparent to most players. Our psychophysical experiment shows that in a task-oriented context such as gaming, the predictive power of saliency maps at design time can be weak. Thus, we argue that a more involved protocol utilizing eye tracking, as part of the computer game design cycle, can be sufficiently robust to succeed in predicting fixation behavior of players

A Testing Environment for Video-Based Multiview

We describe the methodology, design considerations and practical implementation of an environment used in developing and testing video-based, multiview computer vision algorithms