9,041 research outputs found

    AUTOMATIC REGISTRATION OF MULTI-SOURCE MEDIUM RESOLUTION SATELLITE DATA

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    Multi-temporal and multi-source images gathered from satellite platforms are nowadays a fundamental source of information in several domains. One of the main challenges in the fusion of different data sets consists in the registration issue, i.e., the integration into the same framework of images collected with different spatial resolution and acquisition geometry. This paper presents a novel methodology to accomplish this task on the basis of a method that stands out from existing approaches. The whole data (time series) set is simultaneously co-registered with a two-dimensional multiple Least Squares adjustment with different geometric transformations implemented. Some tests were carried out with different geometric transformation models (including similarity, affine, and polynomial) and variable matching thresholds. They showed a sub-pixel precision after the computation of multiple adjustment. The use of multi-image corresponding points allowed the improvement of the registration accuracy and reliability of a time series made up of data imaged with different sensors

    Thermal mapping, geothermal source location, natural effluents and plant stress in the Mediterranean coast of Spain

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    Data obtained by HCMM satellite over a complex area in eastern Spain were evaluated and found to be most useful in studying macrostructures in geology and in analyzing marine currents, layers, and areas (although other satellites provide more data). The upper scale to work with HCMM data appears to be 1:2.000.000. Techniques used in preprocessing, processing, and analyzing imagery are discussed as well as methods for pattern recognition. Surface temperatures obtained for soils, farmlands, forests, geological structures, and coastal waters are discussed. Suggestions are included for improvements needed to achieve better results in geographic areas similar to the study area

    The Shroud Around the Twin Radio Jets in NGC 1052

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    (Abridged) We discuss multiple VLBI continuum and spectral line observations and WSRT spectroscopy of NGC 1052. Sub-parsec scale features move outward at approximately 0.26c in bi-symmetric jets, most likely oriented near the plane of the sky. Absorption and emission signatures reveal ionised, atomic, and molecular components of the surrounding medium. Seven-frequency (1.4 to 43 GHz) VLBA observations show free-free absorption in the inner parsec, probably together with synchrotron self-absorption. There is apparently a geometrically thick but patchy structure oriented roughly orthogonal to the jets. The western jet is receding: it is covered more deeply and extensively. HI spectral line VLBI reveals atomic gas in front of both jets. There appear to be three velocity systems. The deepest, at "high velocities" (receding by 125 to 200 km/s), seems restricted to a shell 1 to 2 pc away from the core, within which this gas might be largely ionised. WSRT spectroscopy has revealed 1667 and 1665 MHz OH absorption with their line ratio varying roughly from 1:1 to 2:1 between -35 and 200 km/s. In the high velocity system the OH profiles are similar to HI, suggesting co-location of that atomic and molecular gas, and leaving unclear the connection to the H2O masing gas seen elsewhere. We have also detected both 18cm OH satellite lines in the high velocity system. They have conjugate profiles: 1612 MHz is in absorption, and 1720 MHz in emission.Comment: 16 pages, 14 figures, LaTeX, includes aa.cls, accepted for publication in Astronomy and Astrophysic
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