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Item Conservative Ray Batching using Geometry Proxies(The Eurographics Association, 2020) Molenaar, Mathijs; Eisemann, Elmar; Wilkie, Alexander and Banterle, FrancescoWe present a method for improving batched ray traversal as was presented by Pharr et al. [PKGH97]. We propose to use conservative proxy geometry to more accurately determine whether a ray has a possibility of hitting any geometry that is stored on disk. This prevents unnecessary disk loads and thus reduces the disk bandwidth.Item Rayground: An Online Educational Tool for Ray Tracing(The Eurographics Association, 2020) Vitsas, Nick; Gkaravelis, Anastasios; Vasilakis, Andreas-Alexandros; Vardis, Konstantinos; Papaioannou, Georgios; Romero, Mario and Sousa Santos, BeatriceIn this paper, we present Rayground; an online, interactive education tool for richer in-class teaching and gradual self-study, which provides a convenient introduction into practical ray tracing through a standard shader-based programming interface. Setting up a basic ray tracing framework via modern graphics APIs, such as DirectX 12 and Vulkan, results in complex and verbose code that can be intimidating even for very competent students. On the other hand, Rayground aims to demystify ray tracing fundamentals, by providing a well-defined WebGL-based programmable graphics pipeline of configurable distinct ray tracing stages coupled with a simple scene description format. An extensive discussion is further offered describing how both undergraduate and postgraduate computer graphics theoretical lectures and laboratory sessions can be enhanced by our work, to achieve a broad understanding of the underlying concepts. Rayground is open, cross-platform, and available to everyone.Item First Order Signed Distance Fields(The Eurographics Association, 2020) Bán, Róbert; Valasek, Gábor; Wilkie, Alexander and Banterle, FrancescoThis paper investigates a first order generalization of signed distance fields. We show that we can improve accuracy and storage efficiency by incorporating the spatial derivatives of the signed distance function into the distance field samples. We show that a representation in power basis remains invariant under barycentric combination, as such, it is interpolated exactly by the GPU. Our construction is applicable in any geometric setting where point-surface distances can be queried. To emphasize the practical advantages of this approach, we apply our results to signed distance field generation from triangular meshes. We propose storage optimization approaches and offer a theoretical and empirical accuracy analysis of our proposed distance field type in relation to traditional, zero order distance fields. We show that the proposed representation may offer an order of magnitude improvement in storage while retaining the same precision as a higher resolution distance field.Item Controllable Caustic Animation Using Vector Fields(The Eurographics Association, 2020) Rojo, Irene Baeza; Gross, Markus; Günther, Tobias; Wilkie, Alexander and Banterle, FrancescoIn movie production, lighting is commonly used to redirect attention or to set the mood in a scene. The detailed editing of complex lighting phenomena, however, is as tedious as it is important, especially with dynamic lights or when light is a relevant story element. In this paper, we propose a new method to create caustic animations, which are controllable through constraints drawn by the user. Our method blends caustics into a specified target image by treating photons as particles that move in a divergence-free fluid, an irrotational vector field or a linear combination of the two. Once described as a flow, additional user constraints are easily added, e.g., to direct the flow, create boundaries or add synthetic turbulence, which offers new ways to redirect and control light. The corresponding vector field is computed by fitting a stream function and a scalar potential per time step, for which constraints are described in a quadratic energy that we minimize as a linear least squares problem. Finally, photons are placed at their new positions back into the scene and are rendered with progressive photon mapping.Item Photon Mapping Superluminal Particles(The Eurographics Association, 2020) Waldemarson, Gustaf; Doggett, Michael; Wilkie, Alexander and Banterle, FrancescoOne type of light source that remains largely unexplored in the field of light transport rendering is the light generated by superluminal particles, a phenomenon more commonly known as Cherenkov radiation [Cˇ37]. By re-purposing the Frank-Tamm equation [FT91] for rendering, the energy output of these particles can be estimated and consequently mapped to photons, making it possible to visualize the brilliant blue light characteristic of the effect. In this paper we extend a stochastic progressive photon mapper and simulate the emission of superluminal particles from a source object close to a medium with a high index of refraction. In practice, the source is treated as a new kind of light source, allowing us to efficiently reuse existing photon mapping methods.