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Team MANAO Melting the frontiers between Light, Shape
"... 2.3.1.1. Using a global approach 3 2.3.1.2. Taking observers into account 4 3. Scientific Foundations.....................................................................5 ..."
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2.3.1.1. Using a global approach 3 2.3.1.2. Taking observers into account 4 3. Scientific Foundations.....................................................................5
Author manuscript, published in "ACM Transactions on Graphics 32, 4 (2013)" Depicting Stylized Materials with Vector Shade Trees
"... Part of the difficulty in depicting stylized materials stems from the fact that the techniques artists use to draw materials are based on accumulated artistic knowledge. These guidelines they use to dehal-00828067, ..."
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Part of the difficulty in depicting stylized materials stems from the fact that the techniques artists use to draw materials are based on accumulated artistic knowledge. These guidelines they use to dehal-00828067,
Depicting Stylized Materials with Vector Shade Trees
"... Figure 1: We describe Vector Shade Trees that represent stylized materials as a combination of basic shade nodes composed of vector graphics primitives (a). Combining these nodes allows the depiction of a variety of materials while preserving traditional vector drawing style and practice. We integra ..."
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Figure 1: We describe Vector Shade Trees that represent stylized materials as a combination of basic shade nodes composed of vector graphics primitives (a). Combining these nodes allows the depiction of a variety of materials while preserving traditional vector drawing style and practice. We integrate our vector shade trees in a vector drawing tool that allows users to apply stylized shading effects on vector line drawings (b,c). This pdf contains png versions of vector art to avoid viewer compatibility problems; full vector versions of our results are in supplemental material. Original line drawing from koconmus, openclipart.org c, colored version c the authors. Vector graphics represent images with compact, editable and scalable primitives. Skillful vector artists employ these primitives to produce vivid depictions of material appearance and lighting. However, such stylized imagery often requires building complex multilayered combinations of colored fills and gradient meshes. We facilitate this task by introducing vector shade trees that bring to vector graphics the flexibility of modular shading representations as known in the 3D rendering community. In contrast to traditional shade trees that combine pixel and vertex shaders, our shade nodes encapsulate the creation and blending of vector primitives that vector artists routinely use. We propose a set of basic shade nodes that we design to respect the traditional guidelines on material depiction described in drawing books and tutorials. We integrate our representation as an Adobe Illustrator plug-in that allows even inexperienced users to take a line drawing, apply a few clicks and obtain a fully colored illustration. More experienced artists can easily refine the illustration, adding more details and visual features, while using all the vector drawing tools they are already familiar with. We demonstrate the power of our representation by quickly generating illustrations of complex objects and materials.
Adobe Systems
, 2011
"... Figure 1: Diffusion curves (left), and the corresponding color image (right). Note the complex shading on the folds and blur on the face. We describe a new vector-based primitive for creating smoothshaded images, called the diffusion curve. A diffusion curve partitions the space through which it is ..."
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Figure 1: Diffusion curves (left), and the corresponding color image (right). Note the complex shading on the folds and blur on the face. We describe a new vector-based primitive for creating smoothshaded images, called the diffusion curve. A diffusion curve partitions the space through which it is drawn, defining different colors on either side. These colors may vary smoothly along the curve. In addition, the sharpness of the color transition from one side of the curve to the other can be controlled. Given a set of diffusion curves, the final image is constructed by solving a Poisson equation whose constraints are specified by the set of gradients across all diffusion curves. Like all vector-based primitives, diffusion curves conveniently support a variety of operations, including geometry-based editing, keyframe animation, and ready stylization. Moreover, their representation is compact and inherently resolution-independent. We describe a GPU-based implementation for rendering images defined by a set of diffusion curves in realtime. We then demonstrate an interactive drawing system for allowing artists to create artworks using diffusion curves, either by drawing the curves in a freehand style, or by tracing existing imagery. The system is simple and intuitive: we show results created by artists after just a few minutes of instruction. Furthermore, we describe a completely automatic conversion process for taking an image and turning it into a set of diffusion curves that closely approximate the original image content.
A Vectorial Framework for Ray Traced Diffusion Curves
"... Diffusion curves allow creating complex, smoothly shaded images by diffusing colors defined at curves. These methods typically require the solution of a global optimization problem (over either the pixel grid or an intermediate tessellated representation) to produce the final image, making fully par ..."
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Diffusion curves allow creating complex, smoothly shaded images by diffusing colors defined at curves. These methods typically require the solution of a global optimization problem (over either the pixel grid or an intermediate tessellated representation) to produce the final image, making fully parallel implementation challenging. An alternative approach, inspired by global illumination, uses 2D ray tracing to independently compute each pixel value. This formulation allows trivial parallelism, but it densely computes values even in smooth regions and sacrifices support for instancing and layering. We describe a sparse, ray traced, multi-layer framework that incorporates many complementary benefits of these existing approaches. Our solution avoids the need for a global solve and trivially allows parallel GPU implementation. We leverage an intermediate triangular representation with cubic patches to synthesize smooth images faithful to the per-pixel solution. The triangle mesh provides a resolution-independent, vectorial representation and naturally maps diffusion curve images to a form natively supported by standard vector graphics and triangle rasterization pipelines. Our approach supports many features which were previously difficult to incorporate into a single system, including instancing, layering, alpha blending, texturing, local blurring, continuity control, and parallel computation. We also show how global diffusion curves can be combined with local painted strokes in one coherent system.
Shading Curves: Vector-Based Drawing With Explicit Gradient Control
"... A challenge in vector graphics is to define primitives that offer flexible manipulation of colour gradients. We propose a new primitive, called a shading curve, that supports explicit and local gradient control. This is achieved by associating shading profiles to each side of the curve. These shadin ..."
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A challenge in vector graphics is to define primitives that offer flexible manipulation of colour gradients. We propose a new primitive, called a shading curve, that supports explicit and local gradient control. This is achieved by associating shading profiles to each side of the curve. These shading profiles, which can be manually manipulated, represent the colour gradient out from their associated curves. Such explicit and local gradient control is challenging to achieve via the diffusion curve process, introduced in 2008, because it offers only implicit control of the colour gradient. We resolve this problem by using subdivision surfaces that are constructed from shading curves and their shading profiles.
Eurographics / ACM SIGGRAPH Symposium on Computer Animation (2014) Vladlen Koltun and Eftychios Sifakis (Editors) Fast Grid-Based Nonlinear Elasticity for 2D Deformations
"... Figure 1: Image warp of a flexible, yet incompressible, elastic sphere pinched between two fingers. The effect was created by providing spatially-varying compression resistance values to make the sphere significantly more area-preserving than its compressible background. We present a deformation tec ..."
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Figure 1: Image warp of a flexible, yet incompressible, elastic sphere pinched between two fingers. The effect was created by providing spatially-varying compression resistance values to make the sphere significantly more area-preserving than its compressible background. We present a deformation technique that constructs 2D warps by using spline curves to specify the starting and target shapes of selected key contours. We generate a two-dimensional deformation map from these contours by simulating a non-linear elastic membrane deforming in accordance with user-specified constraints. Although we support and demonstrate elastic models inspired by physical membranes, we highlight a custom material model for this specific application, which combines the benefits of harmonic interpolation and area-preserving deformations. Our warps are represented via a standard Cartesian lattice and leverage the regularity of this description to enable efficient computation. Specifically, our method resolves the targeting constraints imposed along arbitrarily shaped contours with sub-grid cell precision, without requiring an explicit remeshing of the warp lattice around the constraint curve. We describe how to obtain a well-conditioned discretization of our membrane model even under elaborate constraints and strict area preservation demands, and present a multigrid solver for the efficient numerical solution of the deformation problem.
