Results 1  10
of
27
Antialiasing through stochastic sampling
 SIGGRAPH
, 1985
"... Stochastic sampling techniques, in particular Poisson and jittered sampling, are developed and analyzed. These approaches allow the construction of aliasfree approximations to continuous functions using discrete calculations. Stochastic sampling scatters high frequency information into broadband no ..."
Abstract

Cited by 129 (0 self)
 Add to MetaCart
Stochastic sampling techniques, in particular Poisson and jittered sampling, are developed and analyzed. These approaches allow the construction of aliasfree approximations to continuous functions using discrete calculations. Stochastic sampling scatters high frequency information into broadband noise rather than generating the false patterns produced by regular sampling. The type of randomness used in the sampling process controls the spectral character of the noise. The average sampling rate and the function being sampled determine the amount of noise that is produced. Stochastic sampling is applied adaptively so that a greater number of samples are taken where the function varies most. An estimate is used to determine how many samples to take over a given region. Noise reducing filters are used to increase the efficacy of a given sampling rate. The filter width is adaptively controlled to further improve performance. Stochastic sampling can be applied spatiotcmporally aswell as to other aspects of scene simulation. Ray tracing is one example of an image synthesis approach that can be antialiased by stochastic sampling.
Ray Tracing with Cones
, 1984
"... A new approach to ray tracing is introduced. The definition of a "ray" is extended into a cone by including information on the spread angle and the virtual origin. The advantages of this approach, which tries to model light propagation with more fidelity, include a better method of antia ..."
Abstract

Cited by 111 (3 self)
 Add to MetaCart
A new approach to ray tracing is introduced. The definition of a "ray" is extended into a cone by including information on the spread angle and the virtual origin. The advantages of this approach, which tries to model light propagation with more fidelity, include a better method of antialiasing, a way of calculating fuzzy shadows and dull reflections, a method of calculating the correct level of detail in a procedural model and texture map, and finally, a procedure for faster intersection calculation.
ModelBased 3D Hand Pose Estimation from Monocular Video
"... A novel modelbased approach to 3D hand tracking from monocular video is presented. The 3D hand pose, the hand texture and the illuminant are dynamically estimated through minimization of an objective function. Derived from an inverse problem formulation, the objective function enables explicit use ..."
Abstract

Cited by 24 (2 self)
 Add to MetaCart
A novel modelbased approach to 3D hand tracking from monocular video is presented. The 3D hand pose, the hand texture and the illuminant are dynamically estimated through minimization of an objective function. Derived from an inverse problem formulation, the objective function enables explicit use of temporal texture continuity and shading information, while handling important selfocclusions and timevarying illumination. The minimization is done efficiently using a quasiNewton method, for which we provide a rigorous derivation of the objective function gradient. Particular attention is given to terms related to the change of visibility near selfocclusion boundaries that are neglected in existing formulations. To this end we introduce new occlusion forces and show that using all gradient terms greatly improves the performance of the method. Qualitative and quantitative experimental results demonstrate the potential of the approach.
Algorithms for the Detection and Elimination of Specular Aliasing
 In Proc. Graphics Interface
, 1992
"... This paper introduces an algorithm that, given the geometry and surface characteristics of an object (the Phong highlight model is assumed), detects when specular or highlight aliasing is expected and indicates the correct sampling rate to eliminate it. This is accomplished by noting the geometric p ..."
Abstract

Cited by 9 (1 self)
 Add to MetaCart
(Show Context)
This paper introduces an algorithm that, given the geometry and surface characteristics of an object (the Phong highlight model is assumed), detects when specular or highlight aliasing is expected and indicates the correct sampling rate to eliminate it. This is accomplished by noting the geometric properties of the surface, the direction and distances to the eye and light sources, and the specular shading parameters. Also, an auxiliary algorithm is presented that eliminates the specular aliasing without increasing the sampling rate. It accomplishes this by clamping the specular function parameters to values that will not introduce significant high frequency components. Keywords antialiasing, shading, highlights, image synthesis Introduction An area of research in computer graphics that continues to receive a lot of attention is antialiasing (Crow, 1977; Cook, 1986). Much work, however, has concentrated with the edges of the display primitives, noting, correctly, that the most not...
Antialiasing of Curves by Discrete Prefiltering
, 1997
"... Prefiltering is generally considered the ideal approach to antialiasing but is difficult to perform exactly for complex geometries such as curves or for arbitrary choice of filters. We present a discrete prefiltering technique for antialiasing Bzier curves using arbitrary filters which is numeric ..."
Abstract

Cited by 8 (2 self)
 Add to MetaCart
Prefiltering is generally considered the ideal approach to antialiasing but is difficult to perform exactly for complex geometries such as curves or for arbitrary choice of filters. We present a discrete prefiltering technique for antialiasing Bzier curves using arbitrary filters which is numerically and geometrically robust and whose accuracy is controllable. CR Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image Generation  antialiasing Additional Keywords: Bzier curves, prefiltering 1 INTRODUCTION The causes of aliasing in computer generated imagery are well known and may be broken down into two components: aliasing due to inadequate sampling of the ideal image and aliasing due to incorrect or inadequate reconstruction of the displayed image from the samples. Many techniques have been proposed but there is no ideal or universal solution and compromises have to be made. As Mitchell and Netravali [29] point out, graphics has generally avoided the is...
Antialiasing with Line Samples
"... Abstract. Antialiasing is a necessary component of any high quality renderer. An antialiased image is produced by convolving the scene with an antialiasing filter and sampling the result, or equivalently by solving the antialiasing integral at each pixel. Though methods for analytically computing th ..."
Abstract

Cited by 8 (0 self)
 Add to MetaCart
(Show Context)
Abstract. Antialiasing is a necessary component of any high quality renderer. An antialiased image is produced by convolving the scene with an antialiasing filter and sampling the result, or equivalently by solving the antialiasing integral at each pixel. Though methods for analytically computing this integral exist, they require the continuous twodimensional result of visiblesurface computations. Because these computations are expensive, most renderers use supersampling, a discontinuous approximation to the integral. We present a new algorithm, line sampling, combining a continuous approximation to the integral with a simple visiblesurface algorithm. Line sampling provides high quality antialiasing at significantly lower cost than analytic methods while avoiding the visual artifacts caused by supersampling’s discontinuous nature. A line sample is a line segment in the image plane, centered at a pixel and spanning the footprint of the antialiasing filter. The segment is intersected with scene polygons, visible subsegments are determined, and the antialiasing integral is computed with those subsegments and a onedimensional reparameterization of the integral. On simple scenes where edge directions can be precomputed, one correctly oriented line sample per pixel suffices for antialiasing. Complex scenes can be antialiased by combining multiple line samples weighted according to the orientation of the edges they intersect. 1
ObjectOrder Rendering of Discrete Objects
, 1997
"... This dissertation gives accurate and efficient methods for the objectorder rendering of discrete objects. Discrete objects are typically represented with a volume raster and rendered with a volume rendering algorithm. However, current objectorder volume rendering algorithms suffer from several pro ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
This dissertation gives accurate and efficient methods for the objectorder rendering of discrete objects. Discrete objects are typically represented with a volume raster and rendered with a volume rendering algorithm. However, current objectorder volume rendering algorithms suffer from several problems. First, they require that the volume raster be traversed in a strict visibility order, but existing visibility ordering methods do not always correctly order perspective projections of volume rasters. Second, both perspective and orthographic renderings of volume rasters can contain aliasing artifacts, but current objectorder techniques have no method for addressing these artifacts. Third, computergenerated animations suffer from temporal aliasing artifacts, which can be addressed by adding motion blur. But currently the only motionblur method for objectorder techniques is supersampling, which is very expensive. This
Motion Blur Rendering: State of the Art
 Computer Graphics Forum Volume 30 (2011), number 1
"... Motion blur is a fundamental cue in the perception of objects in motion. This phenomenon manifests as a visible trail along the trajectory of the object and is the result of the combination of relative motion and light integration taking place in film and electronic cameras. In this work, we analyse ..."
Abstract

Cited by 6 (1 self)
 Add to MetaCart
Motion blur is a fundamental cue in the perception of objects in motion. This phenomenon manifests as a visible trail along the trajectory of the object and is the result of the combination of relative motion and light integration taking place in film and electronic cameras. In this work, we analyse the mechanisms that produce motion blur in recording devices and the methods that can simulate it in computer generated images. Light integration over time is one of the most expensive processes to simulate in highquality renders, as such, we make an indepth review of the existing algorithms and we categorize them in the context of a formal model that highlights their differences, strengths and limitations. We finalize this report proposing a number of alternative classifications that will help the reader identify the best technique for a particular scenario.
Analytic Signal Processing for Computer Graphics using Multivariate Polyhedral Splines
, 1995
"... Multivariate polyhedral splines can be used to solve a common image synthesis problem: multivariate integrals defined over multiple geometrically defined domains. The theory is extended from applications in geometric design; this involves both the loosening of some overly restrictive assumptions as ..."
Abstract

Cited by 6 (2 self)
 Add to MetaCart
Multivariate polyhedral splines can be used to solve a common image synthesis problem: multivariate integrals defined over multiple geometrically defined domains. The theory is extended from applications in geometric design; this involves both the loosening of some overly restrictive assumptions as well as the introduction of hybridization, slicing, and weighted splines. Two applications are explored: analytic convolutional filtering for antialiasing and evaluation of projected reconstruction kernels for volume rendering. Filtering can be performed in the continuous domain for high quality antialiasing via Bspline filters. We extensively study a linearly interpolated, filtered triangle. Volume rendering via a linear splatting algorithm can be improved by using a box spline interpolation kernel. This approach avoids aliasing and reconstruction problems, allows progressive rendering directly from hierarchically compressed data, and allows precise evaluation of derivatives, which are necessary for shading. Both antialiasing and volume rendering can benefit from the close connection between continuous and discrete signal processing provided by the Bspline basis. An infinite extent analytic cardinal spline filter is equivalent to an analytic Bspline filter followed by a twopass
Pixelaligned warping for multiprojector tiled displays
 In PROCAMS 2005: IEEE International Workshop on ProjectorCamera Systems
, 2005
"... Multiprojector tiled displays offer a scalable path to highresolution display systems, often in a large format. Such displays have been employed in a range of applications from scientific visualization to collaborative virtual environments. Images projected onto these systems have always looked les ..."
Abstract

Cited by 5 (0 self)
 Add to MetaCart
(Show Context)
Multiprojector tiled displays offer a scalable path to highresolution display systems, often in a large format. Such displays have been employed in a range of applications from scientific visualization to collaborative virtual environments. Images projected onto these systems have always looked less sharp than expected owing to the image warping required to achieve geometrical alignment of the partial images to form the seamless whole. Similar degradation of image quality accompanies keystone correction techniques and image warping onto nonplanar surfaces used in single projector applications. In this paper we discuss the underlying cause of the degradation of apparent image resolution, and we introduce a new class of warping techniques, called pixelaligned warping, that tend to preserve image sharpness at the expense of strict adherence to underlying geometrical constraints that define the desired warp. We demonstrate how such techniques can be used to significantly improve the apparent sharpness of the final image. 1.