Diffusion curves [OBW+ 08] provide a flexible tool to create smooth-shaded images from curves defined with colors. The resulting image is typically computed by solving a Poisson equation that diffuses the curve colors...
详细信息
Diffusion curves [OBW+ 08] provide a flexible tool to create smooth-shaded images from curves defined with colors. The resulting image is typically computed by solving a Poisson equation that diffuses the curve colors to the interior of the image. In this paper we present a new method for solving diffusion curves by using ray tracing. Our approach is analogous to final gathering in global illumination, where the curves define source radiance whose visible contribution will be integrated at a shading pixel to produce a color using stochastic ray tracing. Compared to previous work, the main benefit of our method is that it provides artists with extended flexibility in achieving desired image effects. Specifically, we introduce generalized curve colors called shaders that allow for the seamless integration of diffusion curves with classic 2D graphics including vector graphics (e.g. gradient fills) and raster graphics (e.g. patterns and textures). We also introduce several extended curve attributes to customize the contribution of each curve. In addition, our method allows any pixel in the image to be independently evaluated, without having to solve the entire image globally (as required by a Poisson-based approach). Finally, we present a GPU-based implementation that generates solution images at interactive rates, enabling dynamic curve editing. Results show that our method can easily produce a variety of desirable image effects.
Visual analytics is a powerful paradigm for gaining insight from large, complex data. It seeks to engage the analyst more deeply in data exploration, allowing for iterative sense-making using visual interaction for fa...
详细信息
Visual analytics is a powerful paradigm for gaining insight from large, complex data. It seeks to engage the analyst more deeply in data exploration, allowing for iterative sense-making using visual interaction for fast, intuitive human-computer communication. Although researchers have made much progress in this field, the computer still plays a relatively passive role, reduced mostly to number crunching and record keeping. How can we make the computer a more active participant in the reasoning process? Can a computer be more of a mediator and collaborating partner in this insight-gathering task? A first step toward this goal is to determine how to make a computer a better communicator of the 'insight' it has acquired, and so appeal to the human analyst as a source for creative input. This insight is typically available as some form of formatted knowledge—a computational model. This article draws parallels from established rules of human interpersonal communication. It suggests equivalents by which a computer might use these communication channels, elements, and instruments, employing visual interaction as the bilateral medium. [ABSTRACT FROM PUBLISHER]
The propagation kernel for time dependent radiative transfer is represented by a Feynman path integral (FPI). The FPI is approximately evaluated in the spatial-Fourier domain. Spatial diffusion is exhibited in the ker...
详细信息
The propagation kernel for time dependent radiative transfer is represented by a Feynman path integral (FPI). The FPI is approximately evaluated in the spatial-Fourier domain. Spatial diffusion is exhibited in the kernel when the approximations lead to a Gaussian dependence on the Fourier domain wave vector. The approximations provide an explicit expression for the diffusion matrix. They also provide an asymptotic criterion for the self-consistency of the diffusion approximation. The criterion is weakly violated in the limit of large numbers of scattering lengths. Additional expansion of higher-order terms may resolve whether this weak violation is significant. (C) 2010 Elsevier Ltd. All rights reserved.
Emerging applications in virtual museums, cultural-heritage projects, and digital art preservation require high-quality, high-resolution imaging of objects with fine structure, shape, and texture. Large-format digital...
详细信息
Emerging applications in virtual museums, cultural-heritage projects, and digital art preservation require high-quality, high-resolution imaging of objects with fine structure, shape, and texture. Large-format digital photography can provide such imaging. However, such photography presents unique challenges, particularly sensor-lens mismatch and extended depth of field. A new digital tile-scan large-format camera can acquire high-quality, high-resolution images of static scenes. It employs unique calibration techniques and a novel but simple algorithm for focal-stack processing of very large images with significant magnification variations. The camera automatically collects a set of overlapping focal stacks and processes them into a single high-resolution and extended-depth-of-field image.
We propose a novel adaptive pipeline for continuous collision detection in cloth simulation. The pipeline consists of four components: bounding volume hierarchy (BVH) update, BVH traversal, a skipping frame session, a...
详细信息
We propose a novel adaptive pipeline for continuous collision detection in cloth simulation. The pipeline consists of four components: bounding volume hierarchy (BVH) update, BVH traversal, a skipping frame session, and elementary test processing. The skipping frame session is activated adaptively for skipping both BVH update and BVH traversal during the process of collision detection. The proposed method improves the performance of collision detection in simulating cloth models comparing to some existing feature-based collision detection techniques, as indicated from experimental results.
Sketching is an important enabling technology for modern animation interfaces. The proposed method for analyzing sketches is flexible and works consistently across a variety of software and hardware platforms. Importa...
详细信息
Sketching is an important enabling technology for modern animation interfaces. The proposed method for analyzing sketches is flexible and works consistently across a variety of software and hardware platforms. Importantly, it suits mobile devices' restrictive requirements. The associated framework builds a semantic representation of informal drawings and uses this model along with other properties of the sketch to drive an output module. The method is robust and can run in real time even on devices with limited hardware resources. It has been implemented on a Nintendo DS, an iPhone, and a regular PC. An example application employs it to drive facial expressions. The associated video shows the interface used in real time on several distinct platforms and with different output modules.
In this work a new algorithm is derived for the onboard calibration of three-axis strapdown magnetometers. The proposed calibration method is written in the sensor frame, and compensates for the combined effect of all...
详细信息
In this work a new algorithm is derived for the onboard calibration of three-axis strapdown magnetometers. The proposed calibration method is written in the sensor frame, and compensates for the combined effect of all linear time-invariant distortions, namely soft iron, hard iron, sensor nonorthogonality, and bias, among others. A maximum likelihood estimator (MLE) is formulated to iteratively find the optimal calibration parameters that best fit to the onboard sensor readings, without requiring external attitude references. It is shown that the proposed calibration technique is equivalent to the estimation of a rotation, scaling and translation transformation, and that the sensor alignment matrix is given by the solution of the orthogonal Procrustes problem. Good initial conditions for the iterative algorithm are obtained by a suboptimal batch least squares computation. Simulation and experimental results with low-cost sensors data are presented and discussed, supporting the application of the algorithm to autonomous vehicles and other robotic platforms.
Applications that use games to harness human intelligence to perform various computational tasks are increasing in popularity and may be termed human computation games (HCGs). Most HCGs are collaborative in nature, re...
详细信息
Applications that use games to harness human intelligence to perform various computational tasks are increasing in popularity and may be termed human computation games (HCGs). Most HCGs are collaborative in nature, requiring players to cooperate within a game to score points. Competitive versions, where players work against each other, are a more recent entrant, and have been claimed to address shortcomings of collaborative HCGs such as quality of computation. To date, however, little work has been conducted in understanding how different HCG genres influence computational performance and players' perceptions of such. In this paper we study these issues using image tagging HCGs in which users play games to generate keywords for images. Three versions were created: collaborative HCG, competitive HCG, and a control application for manual tagging. The applications were evaluated to uncover the quality of the image tags generated as well as users' perceptions. Results suggest that there is a tension between entertainment and tag quality. While participants reported liking the collaborative and competitive image tagging HCGs over the control application, those using the latter seemed to generate better quality tags. Implications of the work are discussed.
Uninhabited aerial vehicles provide numerous advantages in fighting wildland fires that include persistent operation and elimination of humans from performing what can be dull, dangerous, and dirty work. Multiple coop...
详细信息
Uninhabited aerial vehicles provide numerous advantages in fighting wildland fires that include persistent operation and elimination of humans from performing what can be dull, dangerous, and dirty work. Multiple cooperating uninhabited aerial vehicles can potentially bring about a paradigm shift in the way we fight complex wildland fires. This paper investigates algorithmic development for cooperative control of a number of uninhabited aerial vehicles engaged in fighting a wildland fire. The paper considers two tasks to be performed by a group of uninhabited aerial vehicles: 1) Cooperative tracking of a fire front for accurate situational awareness, and 2) cooperative, autonomous fire fighting using fire suppressant fluid. The scenario considered in this paper makes the following assumptions: information regarding the location of the fire and position of all uninhabited aerial vehicles is made available to each uninhabited aerial vehicle;and each uninhabited aerial vehicle is equipped with unlimited fire suppressant fluid which extinguishes fire in a circle of specified area directly beneath it. This paper formulates these two tasks of fire fighting based upon optimization of respective utility functions, develops a decentralized control method for the cooperative uninhabited aerial vehicles, and analyzes the system for its stability and its ability to carry out the tasks. The proposed strategies have been verified with the help of extensive simulations. Although simplifying assumptions have been made, this preliminary study presents a framework for path planning and cooperative control of multiple uninhabited aerial vehicles engaged in gathering data and actively fighting forest fires.
A VR-based system for the virtual prototyping of shoes employs a user interface that mimics shoe designer's conventional work style, using a pen and a shoe last as 3D proxy objects. Users sketch design lines onto ...
详细信息
A VR-based system for the virtual prototyping of shoes employs a user interface that mimics shoe designer's conventional work style, using a pen and a shoe last as 3D proxy objects. Users sketch design lines onto the last. For this task, the system employs an algorithm for real-time sketch recognition on curved surfaces. On the basis of the framework of curves, the system creates further design elements (for example, leather pieces) to complete the model. Users can employ three pen-based interaction metaphors to interact directly with design elements, to input values, or to make choices from a menu. A user study shows that conventional designers can easily learn and apply these interaction methods. [ABSTRACT FROM PUBLISHER]
暂无评论