Laboratory validation is an important step in the development of new navigation and estimation algorithms. The laboratory validation process often requires the simulation and/or emulation of vehicles, sensors, and ope...
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Laboratory validation is an important step in the development of new navigation and estimation algorithms. The laboratory validation process often requires the simulation and/or emulation of vehicles, sensors, and operational environments. At Texas A&M University’s Land, Air, and Space Robotics (LASR) Laboratory, robotics is utilized to provide the necessary motion and sensing capabilities to meet this end. A new robotic platform - the Navigation, Estimation, and Sensing Testbed (NEST) - was developed for the LASR Laboratory to aid the algorithm testing and validation process. NEST combines a suite of sensors, powerful onboard computer, rechargeable battery, and supporting power electronics into a compact, modular chassis. The result is a versatile, reusable vehicle emulation and sensing platform that can be applied to a variety of projects and operated on its own or in conjunction with other robotic platforms and computing units. NEST’s hardware and software are discussed, along with typical utilization within the laboratory.
The visualization of vector fields has attracted much attention over the last decade due to the vast variety of applications in science and engineering. Topological methods have been used intensively for global struct...
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The visualization of vector fields has attracted much attention over the last decade due to the vast variety of applications in science and engineering. Topological methods have been used intensively for global structure extraction and analysis. Recently, there has been a growing interest in local structure analysis due to its connection to automatic feature extraction and speed. We present an algorithm that extracts local topological structure of arbitrary regions in a two-dimensional vector field. It is based on a mathematical analysis of the topological vector field structure in these regions. The algorithm deals with piecewise linear vector fields and arbitrary polygonal regions. We have tested the algorithm for well known analytic Vector fields and data sets resulting from computational fluid dynamics. (C) 2000 SPIE and IS&T. [S1017-9909(00)01104-1].
In many measuring applications where several acquisitions are needed, resulting measurement data could be more useful if measuring information is included as part of resulting data. For example, in advanced measuremen...
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In many measuring applications where several acquisitions are needed, resulting measurement data could be more useful if measuring information is included as part of resulting data. For example, in advanced measurement algorithms development, it is common to acquire large amounts of organized data that should be clearly identified for automatic post processing. This paper proposes a new eXtensible Mark-up Language (XML) file structure, to be used as a data log file in generic measurement procedures. Benefits like web easiness, low file size requirements and flexible handling by several software platforms are introduced. Specifically developed software to work with the proposed XML structure is presented and the typical acquisition and processing architecture is presented. To demonstrate the proposed XML structure ability, a simple application example applied to power quality assessment was developed. (C) 2006 Elsevier Ltd. All rights reserved.
Standard ocean color data products from the Medium Resolution Imaging Spectrometer (MERIS) are compared with equivalent regional products in European seas exhibiting different bio-optical properties: the northern Adri...
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Standard ocean color data products from the Medium Resolution Imaging Spectrometer (MERIS) are compared with equivalent regional products in European seas exhibiting different bio-optical properties: the northern Adriatic Sea, the Baltic Sea and the Western Black Sea (ADRS, BLTS and BLKS, respectively). Investigated quantities are: 1) the algal-2 pigment index, alg2;2) the composite-absorption coefficient of yellow substance and non-pigmented particles at 442 nm, a(dg);and 3) the concentration of the total suspended matter, TSM. Regional data products are created using ocean color inversion schemes based on MultiLayer Perceptron (MLP) neural nets trained with field measurements from the Coastal Atmosphere and Sea Time Series (CoASTS) and Bio-Optical mapping of Marine Properties (BiOMaP) programs. MLP input is the remote sensing reflectance Res at MERIS center-wavelengths specifically selected for different water types in view of minimizing the perturbing effects of inaccurate atmospheric correction on the retrieval of regional data products. A new method is also proposed to define the applicability of regional MLPs to input Res. Results indicate that MERIS alg2 values tend to overestimate the equivalent quantity computed with MLP regional algorithms. The agreement between MERIS and regional TSM data products is significantly better than that reported for alg2 and ad, especially for BLKS. Findings highlight the relevance of using regional inversion schemes to evaluate standard products over extended oceanographic regions as a complement to the analysis of match-ups between marine products measured in situ and derived from space-born data. (C) 2013 Elsevier Inc. All rights reserved.
Digital filter design can be performed very efficiently using modern computer tools. The drawback of the numeric-based tools is that they usually generate a tremendous amount of numeric data, and the user might easily...
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Digital filter design can be performed very efficiently using modern computer tools. The drawback of the numeric-based tools is that they usually generate a tremendous amount of numeric data, and the user might easily lose insight into the phenomenon being investigated. The computer algebra systems successfully overcome some problems encountered in the traditional numeric-only approach. In this paper, we introduce an original approach to algorithm development and digital filter design using a computer algebra system. The main result of the paper is the development of an algorithm for an infinite impulse response (IIR) filter design that, theoretically, is impossible to be implemented using the traditional approach. We present a step-by-step procedure which includes derivations of closed-form expressions for (1) the transfer functions of the implemented digital filter which contains the algebraic loop;(2) the closed-form expression for computing the number of requested iteration steps;and (3) the error function representing the difference of the output sample values of the new filter and that of the conventional filter. We demonstrate how one can use some already-known multiplierless digital filter as a start-up filter to design a new digital filter whose passband edge frequency can be simply moved by using a single parameter. As a result, we obtain a multiplierless IIR filter, which belongs to the family of low-power digital filters where multipliers are replaced with a small number of adders and shifters.
A fast two-stage scheme for the search of the motion vectors under varying interframe brightness characteristics, referred to as enhanced motion vectors, is devised. In the first stage of the scheme, a given block and...
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A fast two-stage scheme for the search of the motion vectors under varying interframe brightness characteristics, referred to as enhanced motion vectors, is devised. In the first stage of the scheme, a given block and the corresponding blocks in the search window are mapped into the sum-of-pixel value domain, where two subsets of candidate blocks, one consisting the blocks having the DC values closest to the DC value of the block of interest and the other consisting of those having the farthest DC values are selected. In the second stage, the motion vector is determined by employing these subsets and using the mean square error as the matching criterion. Experimental results show that the proposed technique provides a high prediction accuracy with a low computational load. (c) 2005 SPIE and IS&T.
Window-based correlation algorithms are widely used for stereo matching due to their computational efficiency as compared to global algorithms. In this paper, a multiple window correlation algorithm for stereo matchin...
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Window-based correlation algorithms are widely used for stereo matching due to their computational efficiency as compared to global algorithms. In this paper, a multiple window correlation algorithm for stereo matching is presented which addresses the problems associated with a fixed window size. The developed algorithm differs from the previous multiple window algorithms by introducing a reliability test to select the most reliable window among multiple windows of increasing sizes. This ensures that at least one window is large enough to cover a region of adequate intensity variations while at the same time small enough to cover a constant depth region. A recursive computation procedure is also used to allow a computationally efficient implementation of the algorithm. The outcome obtained from a standard set of images with known disparity maps shows that the generated disparity maps are more accurate as compared to two popular stereo matching local algorithms. (c) 2007 SPIE and IS&T.
We present a color filter array interpolation algorithm to provide the missing colors associated with the commonly used Bayer pattern in digital still camera systems. The developed algorithm utilizes color correlation...
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We present a color filter array interpolation algorithm to provide the missing colors associated with the commonly used Bayer pattern in digital still camera systems. The developed algorithm utilizes color correlation and directional derivative attributes of neighboring color pixels and is thus named C2D2. The main advantage of this algorithm is that it requires no user-defined parameter, as is the case in many edge-adaptive color filter array interpolation algorithms. Both an objective and subjective comparison are carried out with two other popular edge-adaptive algorithms. The results indicate that this algorithm consistently generates lower mean-squared interpolation errors in the RGB and L*a*b* color spaces. (C) 2003 SPIE and IST.
We propose a new method to compress error-diffused bilevel images with resolution scalability. This method is a combination of inverse halftoning and rehalftoning. For the inverse halftoning, we combine 2 x 2 dots int...
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We propose a new method to compress error-diffused bilevel images with resolution scalability. This method is a combination of inverse halftoning and rehalftoning. For the inverse halftoning, we combine 2 x 2 dots into a single pixel of a resolution-reduced image, where each pixel has a multilevel value of 0, 1, 2, 3, and 4. After the inverse halftoning, the resolution-reduced multilevel image is halftoned by using an error diffusion algorithm. Thus, the resolution of the error-diffused bilevel images can be reduced by repetition of the inverse halftoning and rehalftoning processes. After reducing the image size, we encode an error-diffused bilevel image progressively from the lowest resolution image to the highest resolution image. To encode higher resolution images, we use the information in the previously coded lower resolution image. Though the compression ratios of the proposed algorithm are similar to those of progressive Joint Bilevel Image Processing Group (JBIG), the image quality of the resolution-reduced image from the proposed algorithm is much better than that from the progressive JBIG. (C) 2003 SPIE and IST.
A model-based FLIR ATR algorithm is described. It utilizes boundary contrast for target detection and recognition. Boundary contrast is related to the location uncertainty at target boundary points. A polygon model is...
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A model-based FLIR ATR algorithm is described. It utilizes boundary contrast for target detection and recognition. Boundary contrast is related to the location uncertainty at target boundary points. A polygon model is used for deriving target centroid location uncertainty caused by the boundary point location uncertainty. The significance of the work lies in the sound mathematical models used in deriving the relationship between contrast and location uncertainty for the boundary points and the relationship between boundary point location uncertainty and centroid location uncertainty Experiment results show significantly improved performance in detection, recognition, and localization. (C) 2000 SPIE and IS&T. [S1017-9909(00)01602-0].
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