We present a highly efficient, automatic method for the generation of hierarchical surface triangulations. Given a set of scattered points in three-dimensional space, without known connectivity information, our method...
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We present a highly efficient, automatic method for the generation of hierarchical surface triangulations. Given a set of scattered points in three-dimensional space, without known connectivity information, our method reconstructs a valid triangulated surface model in a two-step procedure. First, we apply clustering to the set of given points and identify point subsets in locally nearly planar regions. Second, we construct a surface triangulation from the output of the clustering step. The output of the clustering step is a set of 2-manifold tiles, which locally approximate the underlying, unknown surface. We construct the triangulation of the entire surface by triangulating the individual tiles and triangulating the gaps between the tiles. Since we apply point clustering in a hierarchical fashion we can generate model hierarchies by triangulating various levels resulting from the hierarchical clustering step.
In many applications one is concerned with techniques for visualizing data sets with real-time interaction. One technique for providing real-time performance is through the use of multiresolution techniques. These tec...
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In many applications one is concerned with techniques for visualizing data sets with real-time interaction. One technique for providing real-time performance is through the use of multiresolution techniques. These techniques provide multiple representations of a data set at different levels of detail. The idea is to select a level of detail that can be rendered within the user's time constraints. We discuss a mechanism which renders finer-detailed representations where the data set has a high frequency, and coarser representations where the data set has lower frequency. We present a new technique for storing curvilinear data sets within a quadtree representation and discuss two rendering schemes: an anti-aliasing scheme and a scheme for maintaining a specified frame rate.
A unified Eigenfilter approach is proposed for determining the mean-square-optimal coefficients of the McClellan transformation. The approach applies to all filter shapes without the use of prior knowledge of the prop...
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A unified Eigenfilter approach is proposed for determining the mean-square-optimal coefficients of the McClellan transformation. The approach applies to all filter shapes without the use of prior knowledge of the properties of the coefficients. Several design examples for arbitrarily shaped and oriented 2-D fan, elliptical, and diamond filters are given to demonstrate the results achieved with this method. Comparisons with other recently published methods are made to demonstrate the advantages of our method.
We describe the properties of algorithms based on methods of inhomogeneous diffusion and their application to image and video coding. Filtering by inhomogeneous diffusion has the desirable property of reducing noise a...
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We describe the properties of algorithms based on methods of inhomogeneous diffusion and their application to image and video coding. Filtering by inhomogeneous diffusion has the desirable property of reducing noise and other artifacts while preserving the image structure, maintaining or improving image quality. As a preprocessor, this filtering removes non-perceptible noise, leading to improved compression. As a postprocessor, it suppresses coding artifacts, such as the block impairments of DCT-based coders. Maintaining the basic structure of JPEG, MPEG, and other coders, we describe the improvements possible with inhomogeneous diffusion preprocessing and postprocessing.
We have developed a computer‐aided system (Bony Parts) to analyze periodic bands in fish otoliths (or other structures) for age estimation. The image analysis program first scans the image of a thin otolith section, ...
We have developed a computer‐aided system (Bony Parts) to analyze periodic bands in fish otoliths (or other structures) for age estimation. The image analysis program first scans the image of a thin otolith section, perpendicular to the bands specified by the user. Adjacent scans are averaged and filtered with Fourier transformation or spatial domain convolution. Bands of higher density are detected and are marked and summed on the screen. We evaluated this new technique using subsamples of thin‐sectioned otoliths from the bank rockfishSebastes rufus. The time and effort for cleaning, preparation, sectioning, and mounting are the same for both traditional and computer‐aided techniques. The computer‐aided technique reduced the time and tedium of counting bands, yet still allowed the user to interactively make subjective decisions about aging criteria. Both approaches produced similar readings, but computer‐aided estimates were more precise than traditional readings and required less analysis time. Thus, this new technique allows sample size and precision to be increased for a given amount of effort. Use of this new technique to age 1,897 sections produced von Bertalanffy growth equations that indicate female bank rockfish grow to a larger theoretical maximum size than males (L∞= 500.7 mm versus 438.1 mm total length) but grow at a slightly slower rate (K= 0.054 for females versus 0.073 for males).
We present two applications of wavelet and related techniques to problems arising in medical imaging. Both make considerable use of the edge detection and classification properties of wavelet-type representations. Fir...
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Finite context models improve the performance of chain based encoders to the point that they become attractive, alternative models for binary image compression. The resulting code is within 4% of JBIG at 200 dpi and i...
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Finite context models improve the performance of chain based encoders to the point that they become attractive, alternative models for binary image compression. The resulting code is within 4% of JBIG at 200 dpi and is 9% more efficient at 400 dpi.
This paper considers an objective picture quality scale for color images (PQScolor). PQScolor approximates the mean opinion score satisfactorily, it takes into account the color perception by using color difference an...
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This paper considers an objective picture quality scale for color images (PQScolor). PQScolor approximates the mean opinion score satisfactorily, it takes into account the color perception by using color difference and the properties of visual perception for global features and for localized disturbances. There are two type systems, PQScolor1 is based on Godlove's color difference and PQScolor2 is based on H, V, C signal difference. The correlation coefficient between PQScolor (1, 2) and MOS is more than 0.9, which is very high compared to the value 0.34 obtained for the mean color difference scale.
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