38 research outputs found

    Towards Fully Dynamic Surface Illumination in Real-Time Rendering using Acceleration Data Structures

    Get PDF
    The improvements in GPU hardware, including hardware-accelerated ray tracing, and the push for fully dynamic realistic-looking video games, has been driving more research in the use of ray tracing in real-time applications. The work described in this thesis covers multiple aspects such as optimisations, adapting existing offline methods to real-time constraints, and adding effects which were hard to simulate without the new hardware, all working towards a fully dynamic surface illumination rendering in real-time.Our first main area of research concerns photon-based techniques, commonly used to render caustics. As many photons can be required for a good coverage of the scene, an efficient approach for detecting which ones contribute to a pixel is essential. We improve that process by adapting and extending an existing acceleration data structure; if performance is paramount, we present an approximation which trades off some quality for a 2–3× improvement in rendering time. The tracing of all the photons, and especially when long paths are needed, had become the highest cost. As most paths do not change from frame to frame, we introduce a validation procedure allowing the reuse of as many as possible, even in the presence of dynamic lights and objects. Previous algorithms for associating pixels and photons do not robustly handle specular materials, so we designed an approach leveraging ray tracing hardware to allow for caustics to be visible in mirrors or behind transparent objects.Our second research focus switches from a light-based perspective to a camera-based one, to improve the picking of light sources when shading: photon-based techniques are wonderful for caustics, but not as efficient for direct lighting estimations. When a scene has thousands of lights, only a handful can be evaluated at any given pixel due to time constraints. Current selection methods in video games are fast but at the cost of introducing bias. By adapting an acceleration data structure from offline rendering that stochastically chooses a light source based on its importance, we provide unbiased direct lighting evaluation at about 30 fps. To support dynamic scenes, we organise it in a two-level system making it possible to only update the parts containing moving lights, and in a more efficient way.We worked on top of the new ray tracing hardware to handle lighting situations that previously proved too challenging, and presented optimisations relevant for future algorithms in that space. These contributions will help in reducing some artistic constraints while designing new virtual scenes for real-time applications

    Sonic Interactions in Virtual Environments

    Get PDF

    Sonic Interactions in Virtual Environments

    Get PDF
    This open access book tackles the design of 3D spatial interactions in an audio-centered and audio-first perspective, providing the fundamental notions related to the creation and evaluation of immersive sonic experiences. The key elements that enhance the sensation of place in a virtual environment (VE) are: Immersive audio: the computational aspects of the acoustical-space properties of Virutal Reality (VR) technologies Sonic interaction: the human-computer interplay through auditory feedback in VE VR systems: naturally support multimodal integration, impacting different application domains Sonic Interactions in Virtual Environments will feature state-of-the-art research on real-time auralization, sonic interaction design in VR, quality of the experience in multimodal scenarios, and applications. Contributors and editors include interdisciplinary experts from the fields of computer science, engineering, acoustics, psychology, design, humanities, and beyond. Their mission is to shape an emerging new field of study at the intersection of sonic interaction design and immersive media, embracing an archipelago of existing research spread in different audio communities and to increase among the VR communities, researchers, and practitioners, the awareness of the importance of sonic elements when designing immersive environments

    Sonic interactions in virtual environments

    Get PDF
    This book tackles the design of 3D spatial interactions in an audio-centered and audio-first perspective, providing the fundamental notions related to the creation and evaluation of immersive sonic experiences. The key elements that enhance the sensation of place in a virtual environment (VE) are: Immersive audio: the computational aspects of the acoustical-space properties of Virutal Reality (VR) technologies Sonic interaction: the human-computer interplay through auditory feedback in VE VR systems: naturally support multimodal integration, impacting different application domains Sonic Interactions in Virtual Environments will feature state-of-the-art research on real-time auralization, sonic interaction design in VR, quality of the experience in multimodal scenarios, and applications. Contributors and editors include interdisciplinary experts from the fields of computer science, engineering, acoustics, psychology, design, humanities, and beyond. Their mission is to shape an emerging new field of study at the intersection of sonic interaction design and immersive media, embracing an archipelago of existing research spread in different audio communities and to increase among the VR communities, researchers, and practitioners, the awareness of the importance of sonic elements when designing immersive environments

    Tehnike zrcaljenja u Real-Time računalnoj grafici

    Get PDF
    Reflections have a long history in computer graphics, as they are important for conveying a sense of realism as well as depth and proportion. Their implementations come with a multitude of difficulties, and each solution typically has various trade-offs. Approaches highly depend on the geometry of the reflective surface since curved reflectors are usually more difficult to portray accurately. Techniques can typically be categorized by whether they work with the actual geometry of the reflected objects or with an image of these objects. For curved surfaces, image-based techniques are usually preferred, whereas for planar surfaces the reflected geometry can be used more easily because of the lack of distortion. With current advances in graphics hardware technology, ray tracing is also becoming more viable for real-time applications. Many modern solutions often combine multiple approaches to form a hybrid technique. In this paper, we give an overview of the techniques used in computer graphics applications to create real-time reflections. We highlight the trade-offs that have to be dealt with when choosing a particular technique, as well as their ability to produce interreflections. Finally, we describe how contemporary state-of-the-art rendering engines deal with reflections.Zrcaljenja imaju dugu povijest primjene u računalnoj grafici zbog njihove važnosti u prenošenju realističnosti prikaza te prikaza dubine i omjera na slikama. Pri implementaciji zrcaljenja dolazimo do raznih teškoća i svako novo rješenje često imaju svoju cijenu. Pristupi implementacije ovise o geometriji plohe na kojoj leži prikaz, Što je ploha zakrivljenija, to je teže postići vjerni prikaz. Tehnike možemo kategorizirati u one koje rade sa stvarnom geometrijom zrcaljenih objekata te one koje rade samo sa slikama objekata. Kod zakrivljenih ploha koriste se tehnike bazirane na slikama, dok se kod ravninskih ploha koristi zrcaljena geometrija jer nema iskrivljenja. Zahvaljujući trenutnom razvoju tehnologije grafičkih hardvera, metoda praćenja zraka (ray tracing) postaje sve isplativija u real-time primjeni. Mnoga moderna rješenja kombiniraju razne pristupe i dolazi do hibridnih tehnika. U ovom radu dajemo pregled tehnika korištenih u primjeni računalne grafike za postizanje real-time zrcalnih slika. Naglašavamo probleme koji nastaju pri korištenju određene tehnike te njihove mogućnosti u pogledu stvaranja međuzrcaljenja. Naposljetku, opisujemo kako moderni alati za renderiranje rješavaju probleme zrcaljenj

    Insights Into Stellar Explosions From Infrared Light

    Get PDF
    Massive stars are the workhorse of the Universe. While accounting for a minute fraction of baryonic mass, their influence on the cosmos is profound. Their lives and deaths lead to nucleosynthesis of all elements heavier than helium, including those essential to life. They produce some of the most energetic eruptions and explosions, core-collapse (CC) supernovae (SNe) at the end of their life. These explosions are common, about once per century per galaxy, and are one of the primary drivers of the gas dynamics of their host galaxies. Despite their importance, many facets of the massive stars' evolution and their eventual death in CCSNe are still uncertain. In this thesis, I use a variety of observations in the infrared (IR) part of the electromagnetic spectrum to probe aspects of these stellar explosions elusive to visible light. IR observations of SNe remain sparse compared to the optical, even for the most nearby events. I present the first systematic study of CCSNe light curves from the Spitzer Space Telescope showing trends in IR properties of CCSNe and identifying outliers that exhibit signs of interactions between the SN shock and the circumstellar medium (CSM) ejected from the star. I also present in-depth explorations of nearby SN 2017eaw, a typical and common hydrogen-rich explosion; and SN 2014C, a hydrogen-poor explosion whose shock wave crashes into the CSM containing material lost from the star. IR observations provide insights into the chemical evolution and circumstellar environment in these SNe. In the second part of this thesis, I present the development and commissioning of a near-IR spectropolarimeter WIRC+Pol at Palomar Observatory. WIRC+Pol utilizes a novel, highly efficient polarization grating as its polarimetric beam splitter and spectral disperser. The resulting high sensitivity allows WIRC+Pol to observe sources as faint as J = 14.5 to 0.1% polarimetric accuracy in 2 hours. I also present the first scientific results from the instrument: the spectropolarimetric measurements of four nearby SNe, which are the first such observations in the IR. We detected polarization from SN 2018hna, which allowed us to constrain that its explosion geometry looks similar to the very well-studied SN 1987A observed from a different angle, suggesting the same underlying geometry.</p

    Glossy Probe Reprojection for Interactive Global Illumination

    Get PDF
    International audienceRecent rendering advances dramatically reduce the cost of global illumination. But even with hardware acceleration, complex light paths with multiple glossy interactions are still expensive; our new algorithm stores these paths in precomputed light probes and reprojects them at runtime to provide interactivity. Combined with traditional light maps for diffuse lighting our approach interactively renders all light paths in static scenes with opaque objects. Naively reprojecting probes with glossy lighting is memory-intensive, requires efficient access to the correctly reflected radiance, and exhibits problems at occlusion boundaries in glossy reflections. Our solution addresses all these issues. To minimize memory, we introduce an adaptive light probe parameterization that allocates increased resolution for shinier surfaces and regions of higher geometric complexity. To efficiently sample glossy paths, our novel gathering algorithm reprojects probe texels in a view-dependent manner using efficient reflection estimation and a fast rasterization-based search. Naive probe reprojection often sharpens glossy reflections at occlusion boundaries, due to changes in parallax. To avoid this, we split the convolution induced by the BRDF into two steps: we precompute probes using a lower material roughness and apply an adaptive bilateral filter at runtime to reproduce the original surface roughness. Combining these elements, our algorithm interactively renders complex scenes while fitting in the memory, bandwidth, and computation constraints of current hardware
    corecore