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8th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1981

作者： Wallace, Bruce A. Program of Computer Graphics Cornell University United States

ISBN: (纸本)0897910451

The task of assembling drawings and backgrounds together for each frame of an animated sequence has always been a tedious undertaking using conventional animation camera stands and has contributed to the high cost of animation production. In addition, the physical limitations that these camera stands place on the manipulation of the individual artwork levels restricts the total image-making possibilities afforded by traditional cartoon animation. Documents containing all frame assembly information must also be maintained. This paper presents several computer methods for assisting in the production of cartoon animation, both to reduce expense and to improve the overall quality. Merging is the process of combining levels of artwork into a final composite frame using digital computer graphics. The term "level" refers to a single painted drawing (cel) or background. A method for the simulation of any hypothetical animation camera set-up is introduced. A technique is presented for reducing the total number of merges by retaining merged groups consisting of individual levels which do not change over successive frames. Lastly, a sequence-editing system which controls precise definition of an animated sequence, is described. Also discussed is the actual method for merging any two adjacent levels and several computational and storage optimizations to speed the process. © 1981 ACM.

关键词： Animation

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A color animation system based on the multiplane technique 77

A color animation system based on the multiplane technique

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4th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1977

作者： Levoy, Marc Program of Computer Graphics Cornell University United States

ISBN: (纸本)9781450373555

This paper describes an animation package currently under development at the cornell program of computer graphics. The basic algorithm employed is linear or non-linear interpolation between successive pairs of key frames. These key frames are composed of artwork input by the animator on a graphic tablet and displayed on either a black and white vector scope or a color halftone CRT. The initial working environment is two-dimensional, and the individual images are combined using a multiplane cel animation technique to produce depth and motion illusions. Real-time film previewing, utilizing an on-the-fly interpolation algorithm, provides the artist with instant playback of animated sequences.

关键词： Animation

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Mixed methods for complex kinematic constraints in dynamic figure animation

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The Visual computer 1988年第6期4卷 296-305页

作者： Isaacs, Paul M. Cohen, Michael F. Program of Computer Graphics Cornell University Ithaca 14850 NY United States

Advances for achieving user control of a dynamic simulation of linked figures is presented. The formulation integrates forward and inverse kinematics specification within a mixed method of forward and inverse dynamics simulation. Kinematic specifications can be imposed through kinematic constraints embedded within the dynamics framework. Kinematic constraints may be simple (functions of one degree of freedom), or complex (functions of multiple interrelated degrees of freedom). Thus, keyframed paths, closed loops, point-to-path constraints, and collisions between links and the environment can be simulated. A simultaneous solution for unknown motion and forces of constraint is performed. A Lagrange multiplier method is outlined for incorporating these general constraints into the mathematical formulation of the equations of motion. Results from three example simulations are presented and discussed. © 1988 Springer-Verlag.

关键词： Animation Constraints Dynamics Simulation

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Automated translation and thermal zoning of digital building models for energy analysis

Automated translation and thermal zoning of digital building...

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13th Conference of the International Building Performance Simulation Association, BS 2013

作者： Jones, Nathaniel L. McCrone, Colin J. Walter, Bruce J. Pratt, Kevin B. Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca NY United States

Building energy simulation is valuable during the early stages of design, when decisions can have the greatest impact on energy performance. However, preparing digital design models for building energy simulation typically requires tedious manual alteration. This paper describes a series of five automated steps to translate geometric data from an unzoned CAD model into a multi-zone building energy model. First. CAD input is interpreted as geometric surfaces with materials. Second, surface pairs defining walls of various thicknesses are identified. Third, normal directions of unpaired surfaces are determined. Fourth, space boundaries are defined. Fifth, optionally, settings from previous simulations are applied, and spaces are aggregated into a smaller number of thermal zones. Building energy models created quickly using this method can offer guidance throughout the design process. Copyright © 2011 by IPAC'11/EPS-AG.

关键词： computer aided design

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Combining edges and points for interactive high-quality rendering 03

Combining edges and points for interactive high-quality rend...

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ACM SIGGRAPH 2003 Papers, SIGGRAPH '03

作者： Bala, Kavita Walter, Bruce Greenberg, Donald P. Computer Science Department Cornell University United States Program of Computer Graphics Cornell University United States

ISBN: (纸本)1581137095

This paper presents a new interactive rendering and display technique for complex scenes with expensive shading, such as global illumination. Our approach combines sparsely sampled shading (points) and analytically computed discontinuities (edges) to interactively generate high-quality images. The edge-and-point image is a new compact representation that combines edges and points such that fast, table-driven interpolation of pixel shading from nearby point samples is possible, while respecting *** edge-and-point renderer is extensible, permitting the use of arbitrary shaders to collect shading samples. Shading discontinuities, such as silhouettes and shadow edges, are found at interactive rates. Our software implementation supports interactive navigation and object manipulation in scenes that include expensive lighting effects (such as global illumination) and geometrically complex objects. For interactive rendering we show that high-quality images of these scenes can be rendered at 8 - 14 frames per second on a desktop PC: a speedup of 20 - 60 over a ray tracer computing a single sample per pixel. © 2003 ACM.

关键词： Compressed sensing

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Local illumination environments for direct lighting acceleration

Local illumination environments for direct lighting accelera...

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13th Eurographics Workshop on Rendering

作者： Fernandez, Sebastian Bala, Kavita Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca NY United States

ISBN: (纸本)1581135343

Computing high-quality direct illumination in scenes with many lights is an open area of research. This paper presents a world-space caching mechanism called local illumination environments that enables interactive direct illumination in complex scenes on a cluster of off-the-shelf PCs. A local illumination environment (LIE) caches geometric and radiometric information related to direct illumination. A LIE is associated with every octree cell constructed over the scene. Each LIE stores a set of visible lights, with associated occluders (if they exist). LIEs are effective at accelerating direct illumination because they both eliminate shadow rays for fully visible and fully occluded regions of the scene, and decrease the cost of shadow rays in other regions. Shadow ray computation for the partially occluded regions is accelerated using the cached potential occluders. One important implication of storing occluders is that rendering is accelerated while producing accurate hard and soft shadows. This paper also describes a simple perceptual metric based on Weber's law that further improves the effectiveness of LIEs in the fully visible and partially occluded regions. LIE construction is view-driven, continuously refined, and asynchronous with the shading process. In complex scenes of hundreds of thousands of polygons with up to a hundred lights, the LIEs improve rendering performance by 10x to 30x over a traditional ray tracer.

关键词： Illuminating engineering

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A user interface for interactive cinematic shadow design 02

A user interface for interactive cinematic shadow design

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ACM Transactions on graphics;Proceedings of ACM SIGGRAPH 2002

作者： Pellacini, Fabio Tole, Parag Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca NY United States

ISBN: (纸本)9781581135213

Placing shadows is difficult task since shadows depend on the relative positions of lights and objects in an unintuitive manner. To simplify the task of the modeler, we present a user interface for designing shadows in 3d environments. In our interface, shadows are treated as first-class modeling primitives just like objects and lights. To transform a shadow, the user can simply move, rescale or rotate the shadow as if it was a 2d object on the scene's surfaces. When the user transforms a shadow, the system moves lights or objects in the scene as required and updates the shadows in realtime during mouse movement. To facilitate interaction, the user can also specify constraints that the shadows must obey, such as never casting a shadow on the face of a character. These constraints are then verified in real-time, limiting mouse movement when necessary. We also integrate in our interface fake shadows typically used in computer animation. This allows the user to draw shadowed and non-shadowed regions directly on surfaces in the scene.

关键词： Interactive computer graphics

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The symbiotic relationship between computer graphics and colour imaging

The symbiotic relationship between computer graphics and col...

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Final program and Proceedings of the 4th IS and T/SID Color Imaging Conference: Color Science, Systems and Applications

作者： Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca NY United States

Our goal is to develop physically based lighting models and perceptually based rendering procedures for computer graphics that will allow synthetic images to be generated that are visually and measurably indistinct from real-world images. The research implies the symbiotic relationship which could exist between computer graphics and digital imaging. This presentation describes how work at cornell's program of computer graphics is attempting to achieve this goal.

关键词： Color image processing

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Fast computation of incident solar radiation from preliminary to final building design

Fast computation of incident solar radiation from preliminar...

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12th Conference of International Building Performance Simulation Association Building Simulation 2011, BS 2011

作者： Jones, Nathaniel L. Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca NY United States

Accurate calculation of direct solar radiation with current methods is slow and frequently requires oversimplification of building geometry to obtain expedient performance simulations. This paper describes the use of a fast new method for calculating direct solar gains on architectural CAD models at any stage in design. A pre-processing module computes direct incident solar radiation with high accuracy several orders of magnitude faster than common analytical approaches. The technique is illustrated using preliminary CAD models of two existing buildings that are gradually made more complex through the addition of intricate louvered shading devices, foliage, and adjacent urban structures. Each refinement allows EnergyPlus to calculate much more accurate direct solar gain data with only minimal increase in pre-processing time and no effect on energy simulation time.

关键词： Architectural design

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The back-buffer algorithm: An extension of the radiosity method to dynamic environments

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The Visual computer 1986年第5期2卷 298-306页

作者： Baum, Daniel R. Wallace, John R. Cohen, Michael F. Greenberg, Donald P. Cornell University Program of Computer Graphics Cornell University Ithaca 14853 NY 120 Rand Hall United States

An efficient algorithm is introduced for the production of realistic image sequences of dynamic environments. The practicality of the radiosity method, which computes the interreflection of light within complex diffuse environments independent of viewpoint, is extended to dynamic environments where the paths of moving objects have been predefined. The algorithm takes advantage of the object coherence between static portions of an environment. A preprocessing stage executes once for a given image sequence and precalculates constant geometrical relationships in the environment. When the environment geometry changes, an update stage determines the global illumination using information provided by the preprocessor and the current positions of all moving objects. Test environments show speedups of at least twenty-five times over previous radiosity methods. © 1986 Springer-Verlag.

关键词： computer animation Light reflectance models Radiosity

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