University of Extremadura

About: University of Extremadura is a education organization based out in Badajoz, Spain. It is known for research contribution in the topics: Population & Hyperspectral imaging. The organization has 7856 authors who have published 18299 publications receiving 396126 citations. The organization is also known as: Universidad de Extremadura.

On Endmember Identification in Hyperspectral Images Without Pure Pixels: A Comparison of Algorithms

Abstract: Hyperspectral imaging is an active area of research in Earth and planetary observation. One of the most important techniques for analyzing hyperspectral images is spectral unmixing, in which mixed pixels (resulting from insufficient spatial resolution of the imaging sensor) are decomposed into a collection of spectrally pure constituent spectra, called endmembers weighted by their correspondent fractions, or abundances. Over the last years, several algorithms have been developed for automatic endmember extraction. Many of them assume that the images contain at least one pure spectral signature for each distinct material. However, this assumption is usually not valid due to spatial resolution, mixing phenomena, and other considerations. A recent trend in the hyperspectral imaging community is to design endmember identification algorithms which do not assume the presence of pure pixels. Despite the proliferation of this kind of algorithms, many of which are based on minimum enclosing simplex concepts, a rigorous quantitative and comparative assessment is not yet available. In this paper, we provide a comparative analysis of endmember extraction algorithms without the pure pixel assumption. In our experiments we use synthetic hyperspectral data sets (constructed using fractals) and real hyperspectral scenes collected by NASA's Jet Propulsion Laboratory.

Spanish method of visual impact evaluation in wind farms

Abstract: The present Spanish laws on the procedure to evaluate the environmental impact of wind farms are ambiguous, especially those pertaining to visual impact. There is no specific national law but only regional laws. The main targets of these laws are the conservation of the environment (protected animals and plants), and the noise generated. The focus of this paper, the visual impact, is not taken into account in a direct way in these laws. This work develops a methodology to predict, before its construction, the visual impact that a wind farm can have. This could be used as a consulting tool to analyze and evaluate wind projects, both government-run and private. The developed methodology is quick, concise and clear.