26,064 research outputs found
Ground-based CCD astrometry with wide field imagers. IV. An improved Geometric Distortion Correction for the Blue prime-focus Camera at the LBT
High precision astrometry requires an accurate geometric distortion solution.
In this work, we present an average correction for the Blue Camera of the Large
Binocular Telescope which enables a relative astrometric precision of ~15 mas
for the B_Bessel and V_Bessel broad-band filters. The result of this effort is
used in two companion papers: the first to measure the absolute proper motion
of the open cluster M67 with respect to the background galaxies; the second to
decontaminate the color-magnitude diagram of M67 from field objects, enabling
the study of the end of its white dwarf cooling sequence. Many other
applications might find this distortion correction useful.Comment: 13 pages, 11 figures, 4 tables. accepted for publication on Astronomy
and Astrophysic
Digital image correlation (DIC) analysis of the 3 December 2013 Montescaglioso landslide (Basilicata, Southern Italy). Results from a multi-dataset investigation
Image correlation remote sensing monitoring techniques are becoming key tools for
providing effective qualitative and quantitative information suitable for natural hazard assessments,
specifically for landslide investigation and monitoring. In recent years, these techniques have
been successfully integrated and shown to be complementary and competitive with more standard
remote sensing techniques, such as satellite or terrestrial Synthetic Aperture Radar interferometry.
The objective of this article is to apply the proposed in-depth calibration and validation analysis,
referred to as the Digital Image Correlation technique, to measure landslide displacement.
The availability of a multi-dataset for the 3 December 2013 Montescaglioso landslide, characterized
by different types of imagery, such as LANDSAT 8 OLI (Operational Land Imager) and TIRS
(Thermal Infrared Sensor), high-resolution airborne optical orthophotos, Digital Terrain Models
and COSMO-SkyMed Synthetic Aperture Radar, allows for the retrieval of the actual landslide
displacement field at values ranging from a few meters (2–3 m in the north-eastern sector of the
landslide) to 20–21 m (local peaks on the central body of the landslide). Furthermore, comprehensive
sensitivity analyses and statistics-based processing approaches are used to identify the role of the
background noise that affects the whole dataset. This noise has a directly proportional relationship to
the different geometric and temporal resolutions of the processed imagery. Moreover, the accuracy
of the environmental-instrumental background noise evaluation allowed the actual displacement
measurements to be correctly calibrated and validated, thereby leading to a better definition of
the threshold values of the maximum Digital Image Correlation sub-pixel accuracy and reliability
(ranging from 1/10 to 8/10 pixel) for each processed dataset
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