The registration problem is one of the major issues in augmented reality (AR). Fiducial tracking is gaining interest as a solution to this problem in video see-through AR because of the availability of digitized real ...
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The registration problem is one of the major issues in augmented reality (AR). Fiducial tracking is gaining interest as a solution to this problem in video see-through AR because of the availability of digitized real scenes. There are several AR systems using fiducial tracking, but most of them operate in small desktop workspaces. It is difficult to apply them directly to large scale applications. The wide range of work distance and non-uniform lighting conditions make fiducial detection very difficult. Adding new fiducials requires off-line processing for measuring positions of new fiducials. We propose a fast and robust fiducial detection procedure with carefully designed color fiducials and noise analysis of digitized images. We also present a dynamic workspace extension method with on-line position determination of unknown features. We present a framework for applying AR to large scale applications.
We present a new scheme of data representation for image-based objects. It allows the illumination to be changed interactively without knowing any geometrical information (e.g. depth or surface normal) of the scene, b...
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ISBN:
(纸本)0818680288
We present a new scheme of data representation for image-based objects. It allows the illumination to be changed interactively without knowing any geometrical information (e.g. depth or surface normal) of the scene, but the resulting images are physically correct. The scene is first sampled from different view points and under different illuminations. By treating each pixel on the image plane as a surface element, the sampled images are used to measure the apparent BRDF of each surface element. Two compression schemes, spherical harmonics and discrete cosine transform, are proposed to compress the tabular BRDF data. Whenever the user changes the illumination a certain number of views are reconstructed. The correct user perspective view is then displayed using the standard texture mapping hardware. Hence, the intensity, the type and the number of the light sources can be manipulated interactively.
Block-based compression algorithms have found widespread use in image and video compression standards. Algorithms such as JPEG, however, while very effective in compressing continuous tone images, do not perform well ...
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This paper discusses a hierarchical scheduling framework which reduces the complexity of scheduling synchronous data flow (SDF) graphs onto multiple processors. The core of this framework is a clustering algorithm tha...
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We compare synchronous dataflow (SDF) and cyclo-static dataflow (CSDF), which are each special cases of a model of computation we call dataflow process networks. In SDF actors have static firing rules: They consume an...
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The problem of interpolating data points using a smooth function has many existing solutions. In particular, the use of piecewise polynomials (splines) has provided solutions with user controlled smoothness. In this p...
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The problem of interpolating data points using a smooth function has many existing solutions. In particular, the use of piecewise polynomials (splines) has provided solutions with user controlled smoothness. In this paper we introduce a new interpolation procedure which utilizes multiple knot Hermitian splines. The technique renders the interpolating spline function using fixed point shifts and additions. In applications requiring parallel computation the use of these simpler operations implies a significant reduction in hardware complexity.
Block-based compression algorithms have found widespread use in image and video compression standards. Algorithms such as JPEG, however, while very effective in compressing continuous tone images, do not perform well ...
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Block-based compression algorithms have found widespread use in image and video compression standards. Algorithms such as JPEG, however, while very effective in compressing continuous tone images, do not perform well in compressing multimedia documents which contain text and graphics. With a growing number of applications using images with a high content of both continuous tone data and text, e.g. color facsimile data and educational videos, requires the need for a good compression algorithm. In this paper we present a modified JPEG algorithm for compressing such mixed-mode images which occur in multimedia documents. The algorithm is based on the classification of a block as a kind of text or an image block depending on its DCT coefficients. There can be anywhere from 2 to 256 classes. With such a classification, the same compression algorithm can be applied except that different quantization matrices are used for the different type of blocks. The compression algorithm also uses different entropy codes for the different type of blocks. Simulation results show that the modified JPEG algorithm achieves upto 3 dB gain in PSNR compared to JPEG on multimedia documents.
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