Poisson disk sampling has proven to be very useful and versatile in a variety of computer graphics applications in the past 35 years, since it was first introduced to solve the ray tracing sampling problem. It can sim...
详细信息
Poisson disk sampling has proven to be very useful and versatile in a variety of computer graphics applications in the past 35 years, since it was first introduced to solve the ray tracing sampling problem. It can simply and mathematically be defined as a set of samples (points) in a certain distance space such that each sample is at least a certain distance away from others. Poisson disk sampling is far better than any other sampling methods in the sense that it achieves the combined objective of acquiring the highest quality in visual appearance and producing the least spectral artifacts in the spectral domain. Henceforth, it is favored for ray tracing, which desires the least artifacts when using a small number of ray samples, stippling which requires a uniform distribution of drawing metaphors to represent gray scale smoothly without any noticeable structure, surface remeshing for its random and uniform resultant vertex positions, and many other applications which ask for a uniform distribution of objects in any distance space. In this thesis, I present my three works on Poisson disk sampling, each of which addresses certain problems in a more specific context: Poisson disk sampling on surface by using dual Poisson disk tiling, the acceleration of capacity constrained Voronoi tessellation in 2D Euclidean space and anisotropic Poisson disk sampling in Riemannian distance space. Apart from the detailed description of my own work, prior work on the same topic is also discussed to serve as a background to current Poisson disk sampling research. I categorized the algorithms into 3 chapters based on their working domain: 2D Euclidean space, manifold surface and Riemannian space. Finally, I compare different Poisson disk sampling algorithms in terms of quality and performance in order to provide a reference by which the audience can grasp the usage of Poisson disk sampling in their own research problems.
The article discusses the author's subjective presentations of some of the substantial visions and challenges that the world of the information and communication technology (ICT) faces, and for which computer grap...
详细信息
The article discusses the author's subjective presentations of some of the substantial visions and challenges that the world of the information and communication technology (ICT) faces, and for which computer graphics is an enabling technology. The fundamental concept of image-based rendering (IBR) will be fully developed through applying a set of given images from a scene and synthesizing new views of this scene from these images. The author cites that the challenges of real-time IBR include the enhancement of bandwidth, image analysis, and image synthesis. He stresses that extensive research and development in computer graphic tools and techniques will allow multivariate large-scale data presentation and interaction capabilities for data analysis.
This paper reports on a methodology to reposition the hip joint of a human body finite element model. Repositioning of the hip in flexion - extension, abduction - adduction and internal - external rotations with respe...
详细信息
ISBN:
(纸本)9783033025509
This paper reports on a methodology to reposition the hip joint of a human body finite element model. Repositioning of the hip in flexion - extension, abduction - adduction and internal - external rotations with respect to the pelvic bone has been demonstrated. The developed method is based on computer graphics techniques and permits control over the kinematics of the bones. For some critical areas (in the vicinity of the joint) where distortion of the soft tissue elements is large, a mesh smoothing technique is used to improve the mesh quality. The applicability of the tool is demonstrated by orienting the lower extremity model (with respect to the pelvis) to generate models for various postures. The tool typically can generate a model at 90o flexion, 30o extension, 15o internal / external rotation, 30o abduction, 4o adduction and any combinations of these motions in just a few seconds without any subjective interventions.
In this paper, we present a no-reference video quality metric based on individual measurements of the blockiness artifact. The proposed metric is a modification of the work by Vlachos that measures the strength of blo...
详细信息
ISBN:
(纸本)9781618390837
In this paper, we present a no-reference video quality metric based on individual measurements of the blockiness artifact. The proposed metric is a modification of the work by Vlachos that measures the strength of blockiness artifacts in video sequences. Vlachos' algorithm estimates the blockiness signal strength by comparing the cross-correlation of pixels inside (intra) and outside (inter) the borders of the coding blocking structure of a frame. The proposed algorithm estimates the amount of spatial activity of each frame and uses this measure to modify the blockiness estimates according to its visibility. Contrary to what has been done by Vlachos, we used a Minkowski metric to combine the blockiness estimates for all frames of the video. The proposed algorithm was tested using a set of standard resolution videos compressed with an MPEG-2 enconder.
The building façade model is the most prominent streetscape feature for rendering virtual street models. This paper aims to develop a method to identify street obstacles which hinder photo-realistic texturing of ...
详细信息
ISBN:
(纸本)9781617389160
The building façade model is the most prominent streetscape feature for rendering virtual street models. This paper aims to develop a method to identify street obstacles which hinder photo-realistic texturing of building façade. In order to achieve this, the presented method focuses on two research components. Firstly, we develop an effective grid-based line analysis method to differentiate image elements including building façade from the ones containing street obstacles. The image is divided into a number of grids with a regular size. The dominant façade's geometry plays a significant role as scene knowledge to filter street obstacle by analyzing the numbers of parallel lines and the density of parallel line per each grid. Secondly we present a method to generate an occlusion-free texturing of building façade based-on planar affine transformation and bilinear interpolation. We evaluate the effect of the presented method using real street-view images.
For adequate operations of those precision instruments like hard disc and digital video disc drives, the effects of rotating vibrations must be carefully considered in the design stage. In this paper, an axial-winding...
详细信息
ISBN:
(纸本)9789810860691
For adequate operations of those precision instruments like hard disc and digital video disc drives, the effects of rotating vibrations must be carefully considered in the design stage. In this paper, an axial-winding single-phase brush less DC motor is adopted to form the single-phase spindle motor for its lower cost and better capability of vibration reduction. With proper structure refinement, it is verified that the undesired vibrations and cogging torques of this motor design can be much reduced, and large axial force can be generated to adjust the operational axial displacement. Hence a refined single-phase spindle motor structure that can provide stable operations for related drive applications is thus provided.
The spatial relations representation modeling is a basic task of computer graphics comprehension, however, previous modeling is usually aimed at a certain kind of relations such as direction, topology and distance. Th...
详细信息
Ambient occlusion is a shading method which approximates the global illumination by taking into account attenuation of light due to occlusion. Screen-space ambient occlusion (SSAO) is a scene-independent improvement w...
详细信息
ISBN:
(纸本)9781450305242
Ambient occlusion is a shading method which approximates the global illumination by taking into account attenuation of light due to occlusion. Screen-space ambient occlusion (SSAO) is a scene-independent improvement which performs the visibility test using depth buffer on GPU in real time. Shanmugam *** [2007] efficiently reconstructs the surface using spheres that can be projected to screen, but has the overocclusion issue. Bavoil *** [2008] approximates the ambient occlusion illumination A at a given surface point P by [EQUATION] where w is the sample directions at P within the unit normal-oriented hemisphere with azimuth angle θ and elevation angle α, the tangent angle t(θ) is the signed elevation angle of the surface tangent vector while the horizon angle h(θ) is the maximum elevation α ≥ t(θ) for which w is occluded for all α
This paper describes a cluster-based transcoder that could transcode MPEG-2 format video files to MPEG-4 and H.264 format video files with faster transcoding speed than traditional single PC transcoder1. A seamless me...
详细信息
暂无评论