One way to improve the efficiency of concentrated solar power plants is to use short-term forecasts of Direct Normal Irradiance (DNI) to apply advanced control strategies. These short-term forecasts are obtained using...
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One way to improve the efficiency of concentrated solar power plants is to use short-term forecasts of Direct Normal Irradiance (DNI) to apply advanced control strategies. These short-term forecasts are obtained using sky imagers along with signal and image processing techniques. An important step in DNI forecasting is cloud motion estimation. blockmatching and optical flow algorithms are the most widely used techniques for motion estimation. In this paper, we present a comparative study between the various existing approaches used to estimate the velocity field of clouds. The comparative study is made using a database of images captured by a sky-imaging system developed at PROMES-CNRS laboratory. Computational time and estimation accuracy are the two criteria used to evaluate the performance of each algorithm. The results demonstrate the high performance of optical flow algorithms in terms of accuracy. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
The paper presents a novel Orthogonal Logarithmic Search (OLS) method for block base motion compensation. The performance of the algorithm is evaluated, by using standard QCIF benchmark video sequences and the results...
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ISBN:
(纸本)0819448222
The paper presents a novel Orthogonal Logarithmic Search (OLS) method for block base motion compensation. The performance of the algorithm is evaluated, by using standard QCIF benchmark video sequences and the results are compared to a traditional well-known full search algorithm (FSA) and a sub-optimal method called the Three Step Search (3SS). The evaluation considers the three important metrics, time, entropy and PSNR (Peak Signal to Noise Ratio). The paper also shows that the strength of the algorithm lies in its speed of operation as it is 95% faster than the FSA and over 60% faster than the 3SS. Investigation into-motion estimation algorithms is one of the important issues in the video coding standards such as ISO MPEG-1/2 and ITU-T H.263. These international standard's regularly use a conventional FSA to estimate the motion of pixels between pairs of image block matching algorithms. Since a full search requires intensive computations and the distortion function needs to be evaluated many times for each target block to be matched, the process is very time consuming. Therefore, the main aim of this investigation has been to alleviate this acute problem of search speed and accuracy.
One way to improve the efficiency of concentrated solar power plants is to use short-term forecasts of Direct Normal Irradiance (DNI) to apply advanced control strategies. These short-term forecasts are obtained using...
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Atmospheric turbulence adversely affects imaging systems by causing a random distribution of the index of refraction of the air through which the light must propagate. The resulting image degradation can seriously und...
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ISBN:
(纸本)0819437700
Atmospheric turbulence adversely affects imaging systems by causing a random distribution of the index of refraction of the air through which the light must propagate. The resulting image degradation can seriously undermine the effectiveness of the sensor. In many astronomical systems, which typically have a very narrow field of view, the entire image can be modeled by the convolution of the object with a single point spread function (PSF), and as a result of the narrow field of view, adaptive optical systems can be highly effective in correcting astronomical images. In the case of tactical infrared sensors the field of view is generally much larger than the isoplanatic angle, and the image cannot be modeled by a single point spread function convolved with the scene. Hence, adaptive optical solutions to wide angle infrared imaging over horizonatal paths would be difficult, if not impossible, and post-detection processing of the images is required to mitigate turbulence effects. The overall effect of turbulence within a given isoplanatic patch is not as strong as in the astronomical imaging case due to shorter paths and longer wavelengths. Tilt and low order turbulence modes dominate the aberration experienced within individual isoplanatic patches, greatly simplifying image reconstruction problems. In this paper Ne describe an algorithm for processing video sequences capable of partially correcting these turbulence effects. The algorithm is based on block matching algorithms used in video compression. Simulation results show that this algorithm reduces the squared error of the imagery, and subjectively better images are obtained.
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