Relativistic Effects for Time-Resolved Light Transport

We present a real-time framework which allows interactive visualization of relativistic effects for time-resolved light transport. We leverage data from two different sources: real-world data acquired with an effective exposure time of less than 2 picoseconds, using an ultra-fast imaging technique termed femto-photography, and a transient renderer based on ray-tracing. We explore the effects of time dilation, light aberration, frequency shift and radiance accumulation by modifying existing models of these relativistic effects to take into account the time-resolved nature of light propagation. Unlike previous works, we do not impose limiting constraints in the visualization, allowing the virtual camera to explore freely a reconstructed 3D scene depicting dynamic illumination. Moreover, we consider not only linear motion, but also acceleration and rotation of the camera. We further introduce, for the first time, a pinhole camera model into our relativistic rendering framework, and account for subsequent changes in focal length and field of view as the camera moves through the scene

Novative Rendering and Physics Engines to Apprehend Special Relativity

International audienceRelativity, as introduced by Einstein, is regarded as one of the most important revolutions in the history of physics. Nevertheless, the observation of direct outcomes of this theory on mundane objects is impossible because they can only be witnessed when relative velocities close the speed of light are involved. These effects are so counterintuitive and contradicting with our daily understanding of space and time that physics students find it hard to learn Special Relativity beyond mathematical equations and to understand the deep implications of the theory. Although we cannot travel at the speed of light for real, Virtual Reality makes it possible to experiment the effects of relativity in a 3D immersive environment. Our project is a framework designed to merge advanced 3D graphics with Virtual Reality interfaces in order to create an appropriate environment to study and learn relativity as well as to develop some intuition of the relativistic effects and the quadri-dimensional reality of space-time. In this paper, we focus on designing and implementing an easy-to-use game-like application : a carom billiard. Our implementation includes relativistic effects in an innovative graphical rendering engine and a non-Newtonian physics engine to treat the collisions. The innovation of our approach lies in the ability i) to render in real-time several relativistic objects, each moving with a different velocity vector (contrary to what was achieved in previous works), ii) to allow for interactions between objects, and iii) to enable the user to interact with the objects and modify the scene. To achieve this, we implement the 4D nature of space-time directly at the heart of the rendering engine, and develop an algorithm allowing to access non-simultaneous past events that are visible to the observers at their specific locations and at a given instant of their proper time. We explain how to retrieve the collision event between the pucks and the cushions of the billiard game and we show several counterintuitive results for very fast pucks. The effectiveness of the approach is demonstrated with snapshots of videos where several independent objects travel at velocities close to the speed of light, c

Highlighting interdisciplinarity between physics and mathematics in historical papers on special relativity: design of blended activities for pre-service teacher education

This thesis is framed within the Erasmus+ project titled IDENTITIES, whose aim is to develop interdisciplinary teaching materials for preservice teacher education. In collaboration with the research group in STEM education of Crete, a blended module on special relativity has been developed. The module is based on an analysis of the original texts by Lorentz, Poincaré, Einstein and Minkowski (written between 1904 and 1908), aimed to recognise the interplay between mathematics and physics implemented in the four papers. The analysis has been carried out by applying the 'Boundary Crossing and Boundary Object' research framework developed in 2011 by Akkermann and Bakker. The results of the analysis show that Lorentz Transformations can be read as a Boundary Object and this lens allows for different nuances of the interplay between mathematics and physics to be recognised in the four papers. A series of activities to be conducted in blended mode in a pre-service teacher education course have been designed with the goal of exploiting special relativity as a context to develop interdisciplinary skills