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Toward the light field display: Autostereoscopic rendering via a cluster of projectors

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2008年第1期14卷 84-96页

作者： Yang, Ruigang Huang, Xinyu Li, Sifang Jaynes, Christopher Univ Kentucky Dept Comp Sci Lexington KY 40507 USA Cisco Syst Inc San Jose CA 95134 USA Mersive Technol Inc Lexington KY 40507 USA

Ultimately, a display device should be capable of reproducing the visual effects observed in reality. In this paper, we introduce an autostereoscopic display that uses a scalable array of digital light projectors and a projection screen augmented with microlenses to simulate a light field for a given three-dimensional scene. Physical objects emit or reflect light in all directions to create a light field that can be approximated by the light field display. The display can simultaneously provide many viewers from different viewpoints a stereoscopic effect without head tracking or special viewing glasses. This work focuses on two important technical problems related to the light field display: calibration and rendering. We present a solution to automatically calibrate the light field display using a camera and introduce two efficient algorithms to render the special multiview images by exploiting their spatial coherence. The effectiveness of our approach is demonstrated with a four-projector prototype that can display dynamic imagery with full parallax.

关键词： virtual reality display algorithms projector calibration image based rendering

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Planar Shape Interpolation Based On Teichmuller Mapping

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COMPUTER GRAPHICS FORUM 2016年第7期35卷 43-56页

作者： Nian, Xianshun Chen, Falai Univ Sci & Technol China Sch Math Sci Hefei 230026 Anhui Peoples R China

Shape interpolation is a classical problem in computer graphics and has been widely investigated in the past two decades. Ideal shape interpolation should be natural and smooth which have good properties such as affine and conformal reproduction, bounded distortion, no fold-overs, etc. In this paper, we present a new approach for planar shape interpolation based on Teichmuller maps - a special type of maps in the class of quasi-conformal maps. The algorithm consists of two steps. In the first step, a Teichmuller map is computed from the source shape to the target shape, and then the Beltrami coefficient is interpolated such that the conformal distortion is linear with respect to the time variable. In the second step, the intermediate shape is reconstructed by solving the Beltrami equation locally over each triangle and then stitching the mapped triangles by conformal transformations. The new approach preserves all the good properties mentioned above and produces more natural and more uniform intermediate shapes than the start-of-the-art methods. Especially, the conformal distortion changes linearly with respect to the time variable. Experiment results show that our method can produce appealing results regardless of interpolating between the same or different objects.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.3 [Computer Graphics]: Picture/Image Generation&mdash display algorithms I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism&mdash Animation

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Real-time point-based rendering using visibility map

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2008年第1期E91D卷 124-131页

作者： Shin, Byeong-Seok Oh, Dong-Ryeol Kang, Daniel Inha Univ Dept Comp Sci & Informat Engn Inchon 402751 South Korea

Because of its simplicity and intuitive approach, point-based rendering has been a very popular research area. Recent approaches have focused on hardware-accelerated techniques. By applying a deferred shading scheme, both high-quality images and high-performance rendering have been achieved. However, previous methods showed problems related to depth-based visibility computation. We propose an extended point-based rendering method using a visibility map. In our method we employ a distance-based visibility technique (replacing depth-based visibility), an averaged position map and an adaptive fragment processing scheme, resulting in more accurate and improved image quality, as well as improved rendering performance.

关键词： display algorithms point-based rendering deferred shading hardware accelerated graphics

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Visualizing the Positional and Geometrical Variability of Isosurfaces in Uncertain Scalar Fields

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COMPUTER GRAPHICS FORUM 2011年第3期30卷 951-960页

作者： Pfaffelmoser, Tobias Reitinger, Matthias Westermann, Ruediger Tech Univ Munich Comp Graph & Visualizat Grp D-8000 Munich Germany

We present a novel approach for visualizing the positional and geometrical variability of isosurfaces in uncertain 3D scalar fields. Our approach extends recent work by Pothkow and Hege [PH10] in that it accounts for correlations in the data to determine more reliable isosurface crossing probabilities. We introduce an incremental update-scheme that allows integrating the probability computation into front-to-back volume ray-casting efficiently. Our method accounts for homogeneous and anisotropic correlations, and it determines for each sampling interval along a ray the probability of crossing an isosurface for the first time. To visualize the positional and geometrical uncertainty even under viewing directions parallel to the surface normal, we propose a new color mapping scheme based on the approximate spatial deviation of possible surface points from the mean surface. The additional use of saturation enables to distinguish between areas of high and low statistical dependence. Experimental results confirm the effectiveness of our approach for the visualization of uncertainty related to position and shape of convex and concave isosurface structures.

关键词： I.3.3 [Computer Graphics]: Picture/Image Generation display algorithms Viewing algorithms

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Interactive Urban Context-Aware Visualization via Multiple Disocclusion Operators

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2016年第7期22卷 1862-1874页

作者： Deng, Hao Zhang, Liqiang Mao, Xiancheng Qu, Huamin Cent S Univ Dept Geoinfomat Changsha Hunan Peoples R China Beijing Normal Univ State Key Lab Remote Sensing Sci Beijing 100875 Peoples R China Hong Kong Univ Sci & Technol Dept Comp Sci & Engn Kowloon Hong Kong Peoples R China

In 3D urban environments, features of interest (FOIs) are often occluded by clusters of buildings, which prevent a clear overview of important spatial features. State-of-the-art disocclusion methods for urban environments fall short of preserving cityscape appearance or require time-consuming computation. These methods use only one or two operators for disocclusion and might not strike a good balance between disocclusion and distortion control. We present a novel, automatic method enabling interactive context-aware visualization of urban features of interest, which combines four effective disocclusion operators including viewpoint elevation, road shifting, building scaling, and building displacement to disocclude the features of interest. Our method provides an optimum compromise among the disocclusion operators via an efficient constrained optimization and the post-polishing phrases, which minimizes the distortions while enforcing the visibility of the FOIs. The 3D views generated at interactive frame rates ensure a resemblance in the cityscape appearance to its original ones and provide a good overview of the FOIs. The experiments with real data demonstrate that our method can greatly facilitate tasks such as navigation, wayfinding, and information overlay.

关键词： Occlusion reduction context-aware visualization interactive visualization display algorithms map generalization

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Efficient Contrast Effect Compensation with Personalized Perception Models

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COMPUTER GRAPHICS FORUM 2015年第3期34卷 211-220页

作者： Mittelstaedt, Sebastian Keim, Daniel A. Univ Konstanz Constance Germany

Color is one of the most effective visual variables and is frequently used to encode metric quantities. Contrast effects are considered harmful in data visualizations since they significantly bias our perception of colors. For instance, a gray patch appears brighter on a black background than on a white background. Accordingly, the perception of color-encoded data items depends on the surround in the rendered visualization. A method that compensates for contrast effects has been presented previously, which significantly improves the users' accuracy in reading and comparing color encoded data. The method utilizes established perception models to compensate for contrast effects, assuming an average human observer. In this paper, we provide experiments that show a significant difference in the perception of users. We introduce methods to personalize contrast effect compensation and show that this outperforms the original method with a user study. We, further, overcome the major limitation of the original method, which is a runtime of several minutes. With the use of efficient optimization and surrogate models, we are able to reduce runtime to milliseconds, making the method applicable in interactive visualizations.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.3 [Computer Graphics]: Picture/Image Generation&mdash display algorithms

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Speed-up technique for a local automatic colour equalization model

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COMPUTER GRAPHICS FORUM 2006年第1期25卷 5-14页

作者： Artusi, A Gatta, C Marini, D Purgathofer, W Rizzi, A Intercoll Nicosia Dept Comp Sci Nicosia Cyprus Vienna Univ Technol Inst Comp Graph & Algorithms Vienna Austria Univ Milan Dipartimento Tecnol Informaz Milan Italy Univ Milan Dipartimento Informaz & Comunicaz Milan Italy

In this paper we propose a speed-up technique for a local automatic colour equalization operator derived from a model of the human vision system. This method is characterized by local and global filtering effects, that simultaneously achieve different equalization tasks e.g. performing colour and lightness constancy, realizing dynamic image data driven stretching, controlling the contrast. We describe a way to quickly create a filtering mapping function to perform the global component of the mapping. This method is based on singular value decomposition (SVD) applied to sampled and filtered points in the input image. Then, the local information is added computing the basic algorithm on a neighbourhood of each input pixel. A slight quality loss is the price that we have to pay for a speed-up of more than two orders of magnitude of the basic algorithm. We present the results on several images and discuss the efficiency and the drawbacks of the speed-up technique.

关键词： display algorithms applications image display

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Prostate Cancer Visualization from MR Imagery and MR Spectroscopy

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COMPUTER GRAPHICS FORUM 2011年第3期30卷 1051-1060页

作者： Marino, Joseph Kaufman, Arie SUNY Stony Brook Stony Brook NY 11790 USA

Prostate cancer is one of the most prevalent cancers among males, and the use of magnetic resonance imaging (MRI) has been suggested for its detection. A framework is presented for scoring and visualizing various MR data in an efficient and intuitive manner. A classification method is introduced where acumulative score volume is created which takes into account each of three acquisition types. This score volume is integrated into a volume rendering framework which allows the user to view the prostate gland, the multi-modal score values, and the surrounding anatomy. A visibility persistence mode is introduced to automatically avoid full occlusion of a selected score and indicate overlaps. The use of GPU-accelerated multi-modal single-pass ray casting provides an inter-active experience. User driven importance rendering allows the user to gain insight into the data and can assist in localization of the disease and treatment planning. We evaluate our results against pathology and radiologists' determinations

关键词： I.3.3 [Computer Graphics]: Picture/Image Generation display algorithms I.3.6 [Computer Graphics]: Methodology and Techniques Interaction techniques I.3.8 [Computer Graphics]: Applications J.3 [Life and Medical Sciences]: Health

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Real-time adaptive radiometric compensation

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2008年第1期14卷 97-108页

作者： Grundhofer, Anselm Bimber, Oliver Bauhaus Univ Media Fac D-99423 Weimar Germany

Recent radiometric compensation techniques make it possible to project images onto colored and textured surfaces. This is realized with projector- camera systems by scanning the projection surface on a per-pixel basis. Using the captured information, a compensation image is calculated that neutralizes geometric distortions and color blending caused by the underlying surface. As a result, the brightness and the contrast of the input image is reduced compared to a conventional projection onto a white canvas. If the input image is not manipulated in its intensities, the compensation image can contain values that are outside the dynamic range of the projector. These will lead to clipping errors and to visible artifacts on the surface. In this article, we present an innovative algorithm that dynamically adjusts the content of the input images before radiometric compensation is carried out. This reduces the perceived visual artifacts while simultaneously preserving a maximum of luminance and contrast. The algorithm is implemented entirely on the GPU and is the first of its kind to run in real time.

关键词： computer graphics picture/image generation display algorithms image processing computer vision radiometry reflectance enhancement color

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Surface subdivision for generating superquadrics

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VISUAL COMPUTER 1998年第1期14卷 1-17页

作者： Montiel, ME Aguado, AS Zaluska, E Univ Southampton Southampton Hants England

Superquadrics have been considered as important models for part-level description in computer graphics and computer vision. The description power of these models resides in their parameterised nature, which allows the definition of a wide variety of shapes, yet maintains a compact characterisation. We present a subdivision technique for modelling and displaying superquadrics. The method defines the surface of a superquadric as a deformation of an ellipsoid. The linear are-length parameterisation obtained provides a regular distribution of the parameters along the surface. Furthermore, the definition simplifies computations in scanning by avoiding the evaluation of rational exponents. We exploit the geometric properties of an ellipsoid during subdivision for additional simplification.

关键词： modelling of surfaces surface subdivision parametric surfaces superquadrics superellipses rendering techniques display algorithms curve tracing tessellation reparameterisation deformations

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