Browsing by Author "Vanderhaeghe, David"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    EUROGRAPHICS 2022: Short Papers Frontmatter
    (The Eurographics Association, 2022) Pelechano, Nuria; Vanderhaeghe, David; Pelechano, Nuria; Vanderhaeghe, David
  • Thumbnail Image
    Item
    Global Illumination Shadow Layers
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) DESRICHARD, François; Vanderhaeghe, David; PAULIN, Mathias; Boubekeur, Tamy and Sen, Pradeep
    Computer graphics artists often resort to compositing to rework light effects in a synthetic image without requiring a new render. Shadows are primary subjects of artistic manipulation as they carry important stylistic information while our perception is tolerant with their editing. In this paper we formalize the notion of global shadow, generalizing direct shadow found in previous work to a global illumination context. We define an object's shadow layer as the difference between two altered renders of the scene. A shadow layer contains the radiance lost on the camera film because of a given object. We translate this definition in the theoretical framework of Monte-Carlo integration, obtaining a concise expression of the shadow layer. Building on it, we propose a path tracing algorithm that renders both the original image and any number of shadow layers in a single pass: the user may choose to separate shadows on a per-object and per-light basis, enabling intuitive and decoupled edits.
  • Thumbnail Image
    Item
    Shadow Layers for Participating Media
    (© 2022 Eurographics ‐ The European Association for Computer Graphics and John Wiley & Sons Ltd, 2022) Desrichard, François; Vanderhaeghe, David; Paulin, Mathias; Hauser, Helwig and Alliez, Pierre
    In the movie industry pipeline, rendering programs output the main image along with a collection of Arbitrary Output Variable layers (AOVs) that retain specific information on light transport and scene properties in image space. Compositing artists use AOVs to improve the quality and appearance of the rendered picture during post‐processing, according to the artistic goal of the shot. In particular, cast shadows are manipulated to support narration and storytelling, as the human perception tolerates non‐physical edits. Conventional path tracing renderers often propose a shadow matte AOV containing radiance lost when shadow rays are occluded. Previous work has shown that they incorrectly estimate shadow and miss occluded radiance from indirect light sources, and that shadow layers must be used to correctly recover radiance from single, solid occluders. In this paper, we generalise shadow layers to an arbitrary number of occluders, and add support for participating media. We begin by quantifying the radiance loss between the radiative transfer equation and the rendering equation, and translate it into a path integral formulation for an efficient Monte Carlo integration. We propose a prototype implementation that renders the main image and shadow layers in a single pass with an affordable computational overhead.