and FRÉDO DURAND MIT CSAILWe propose a generalized approach to decoupling shading from visibility sampling in graphics pipelines, which we call decoupled sampling. Decoupled sampling enables stochastic supersampling of motion and defocus blur at reduced shading cost, as well as controllable or adaptive shading rates which trade off shading quality for performance. It can be thought of as a generalization of multisample antialiasing (MSAA) to support complex and dynamic mappings from visibility to shading samples, as introduced by motion and defocus blur and adaptive shading. It works by defining a many-to-one hash from visibility to shading samples, and using a buffer to memoize shading samples and exploit reuse across visibility samples. Decoupled sampling is inspired by the Reyes rendering architecture, but like traditional graphics pipelines, it shades fragments rather than micropolygon vertices, decoupling shading from the geometry sampling rate. Also unlike Reyes, decoupled sampling only shades fragments after precise computation of visibility, reducing over-shading.We present extensions of two modern graphics pipelines to support decoupled sampling: a GPU-style sort-last fragment architecture, and a Larrabee-style sort-middle pipeline. We study the architectural implications of decoupled sampling and blur, and derive end-to-end performance estimates on real applications through an instrumented functional simulator. We demonstrate high-quality motion and defocus blur, as well as variable and adaptive shading rates.
Displacement Mapping is an effective technique for encoding the high levels of detail found in today's triangle based surface models. Extending the hardware rendering pipeline to be capable of handling displacement maps as geometric primitives, will allow highly detailed models to be constructed without requiring large numbers of triangles to be passed from the CPU to the graphics pipeline. We present a new approach based on recursive tessellation that adapts to the surface complexity described by the displacement map. We also ensure that the resolution of the displaced mesh is tessellated with respect to the current view point. Our tessellation scheme performs all tests only on triangle edges to avoid generating cracks on the displaced surface. The main decision for vertex insertion is based on two comparisons involving the average height surrounding the vertices and the normals at the vertices. Individually, the tests will fail to tessellate a mesh satisfactorily, but their combination achieves good results.We propose several additions to the typical hardware rendering pipeline in order to achieve displacement map rendering in hardware. The mesh tessellation is placed within the rendering pipeline so that we can take advantage of the pre-existing vertex transformation units to perform the setup calculations for our view dependent test. Our method adds only simple arithmetic and comparison operations to the graphics pipeline and makes use of existing units for calculations wherever possible.
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Figure 1: This paper presents a method for automatically constructing 3D meshes from a single piece of concept artwork. This figure shows how a typical 2D concept image (a) is separated from the background (b) and how a bent skeleton (c) is generated and used to create polygonal shells (d). The profile view (e) shows clearly how the shells create a 3D representation of the input image. The final model (f -h) is mapped with textures based on the initial concept artwork and contains bone and vertex weighting information appropriate for animation. Details such as the hair and ears are correctly transformed into 3D, and mechanical objects such as the gun and knife have sharp edges. AbstractIn this paper we present a new method for automatically constructing 3D meshes from a single input image. With the increasing content demands of modern digital entertainment and the expectation of involvement from users, automatic artist-free systems are an important step in allowing user generated content and rapid game prototyping. Our system proposes a novel heuristic for the creation of a 3D mesh from a single piece of non-occluding 2D concept art. By extracting a skeleton structure, approximating the 3D orientation and analysing line curvature properties, appropriate centrepoints can be found around which to create the cross-sectional slices used to build a final triangle mesh. Our results show that a single 2D input image can be used to generate a rigged 3D lowpolygon model suitable for use in realtime applications.
Adaptive subdivision of triangular meshes is highly desirable for surface generation algorithms including adaptive displacement mapping in which a highly detailed model can be constructed from a coarse triangle mesh and a displacement map. The communication requirements between the CPU and the graphics pipeline can be reduced if more detailed and complex surfaces are generated, as in displacement mapping, by an adaptive tessellation unit which is part of the graphics pipeline. Generating subdivision surfaces requires a large amount of memory in which multiple arbitrary accesses are required to neighbouring vertices to calculate the new vertices. In this paper we present a meshing scheme and new architecture for the implementation of adaptive subdivision of triangular meshes that allows for quick access using a small memory making it feasible in hardware, while at the same time allowing for new vertices to be adaptively inserted. The architecutre is regular and characterized by an efficient data management that minimizes the data storage and avoids the wait cycles that would be associated with the multiple data accesses required for traditional subdivision. This architecture is presented as an improvement for adaptive displacement mapping algorithms, but could also be used for adaptive subdivision surface generation in hardware.
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