70 research outputs found
The IEEE GRSS standardized remote sensing data website: A step towards "science 2.0" in remote sensing
The issue of homogeneity in performance assessment of proposed algorithms for information extraction is generally perceived also in the Earth Observation (EO) domain. Different authors propose different datasets to test their developed algorithms and to the reader it is frequently difficult to assess which is better for his/her specific application, given the wide variability in test sets that makes pure comparison of e.g. accuracy values less meaningful than one would desire. With our work, we gave a modest contribution to ease the problem by making it possible to automatically distribute a limited set of possible "standard" open datasets, together with some ground truth info, and automatically assess processing results provided by the users
The two tails of PSR J2055+2539 as seen by Chandra: analysis of the nebular morphology and pulsar proper motion
We analyzed two Chandra observations of PSR J2055+2539 (for a total
integration time of 130 ks) in order to measure its proper motion and
study its two elongated nebular features. We did not detect the proper motion,
setting an upper limit of 240 mas yr (3 level), that translates
into an upper limit on the transverse velocity of 700 km s, for an
assumed distance of 600 pc. A deep H observation did not reveal the
bow-shock associated with a classical pulsar wind nebula, thus precluding an
indirect measurement of the proper motion direction. We determined the main
axes of the two nebulae, which are separated by an angle of 160.8, using a new approach based on the Rolling Hough Transformation
(RHT). We analyzed the shape of the first 8' (out of the 12' seen by
XMM-Newton) of the brighter, extremely collimated one. Based on a combination
of our results from a standard analysis and a nebular modeling obtained from
the RHT, we find that the brightest nebula is curved on an arcmin-scale, with a
thickness ranging from " to " and a possible (single or
multiple) helicoidal pattern. We could not constrain the shape of the fainter
nebula. We discuss our results in the context of other known similar features,
with particular emphasis on the Lighthouse nebula (associated with PSR
J11016101). We speculate that a peculiar geometry of the powering pulsar may
play an important role in the formation of such features.Comment: 12 pages, 9 figures, 1 table; accepted by Astronomy & Astrophysic
Tile mapping of urban area extent in VHR SAR images
At the high resolutions attainable with the new generation space-borne sensors, the focus moves increasingly from spectral
characteristics to geometric features. This trend is even more evident for urban areas which tend to show an unpaired concentration of
linear features with respect to any other land cover. This naturally applies to both optical and radar images, and suggests one may use
local concentration of linear features to gauge the presence of urban structures. In this paper we exploit a linear feature extractor to
map the extent of urban areas in very high resolution optical and SAR images
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