4,065 research outputs found
Improved depth recovery in consumer depth cameras via disparity space fusion within cross-spectral stereo.
We address the issue of improving depth coverage in consumer depth cameras based on the combined use of cross-spectral stereo and near infra-red structured light sensing. Specifically we show that fusion of disparity over these modalities, within the disparity space image, prior to disparity optimization facilitates the recovery of scene depth information in regions where structured light sensing fails. We show that this joint approach, leveraging disparity information from both structured light and cross-spectral sensing, facilitates the joint recovery of global scene depth comprising both texture-less object depth, where conventional stereo otherwise fails, and highly reflective object depth, where structured light (and similar) active sensing commonly fails. The proposed solution is illustrated using dense gradient feature matching and shown to outperform prior approaches that use late-stage fused cross-spectral stereo depth as a facet of improved sensing for consumer depth cameras
Les historiens grecs entre la cité et l'exil
International audienceIn his treatise How to write history Lucian states that «in his books» the historian should be «a foreigner and a man without a country, independent, subject to no sovereign». This statement is not a sophistic paradox. It comes from a long traditionregarding Greek historians, which considers a biographical accident – the situation of exile – as a necessary condition for historical inquiry. This paper aims at reconstructing this tradition, from Herodotus to Arrian, and at showing it to be one of the most important paradigms of historical knowledge
Worldwide Needs for Safe Drinking Water Are Underestimated: Billions of People Are Impacted
An official statistic from the United Nations at the end of 2008 was that 884 million people lacked access to "improved" water sources. But many unaware of the precise meaning behind "improved", and indeed even the UN General Assembly itself, have convinced the public that 884 million is the number of people who lack access to safe water. The author argues that this is a serious underestimation. Not only does "improved" not ensure potability, it also fails to incorporate all aspects of the right to water. Furthermore, the question of access can not easily be answered with a yes or no; different modes of access may be more or less satisfactory. Shedding light on the order of magnitude truly involved in the water problem, this report provides rough estimates of the number of people whose right to safe drinking water is inadequately met
Ionospheric Behavior During Descendant Phase of Solar Cycle 20
This study describes the behavior of the peak value of the ionospheric concentration (foF2) during the descending phase of Solar Cycle 20. In order to understand the ionospheric dependency with the solar activity during the descending phase of solar cycle 20 (1970 to 1975), peak ionospheric values for multiple ionospheric stations have been downloaded from the National Oceanic and atmospheric Administration (NOAA)’s National Geophysics Data Center (NGDC) database and analyzed using a new approach: The study of daily maximum and minimum values. Many interesting characteristics of the ionospheric behavior were detected, while the trend of the maxima closely follows the trend of the solar activity (as captured by different indexes), the trend of the minima is 2 – 4 times less pronounced. The variability of both values seems to be consistently linked with the solar activity trend, but the clear picture does not emerge from this analysis. In order to clarify these trends, we plan to continue the exploration of the multiple dependencies of the ionospheric behavior with the solar activity
Topological Background Fields as Quantum Degrees of Freedom of Compactified Strings
It is shown that background fields of a topological character usually
introduced as such in compactified string theories correspond to quantum
degrees of freedom which parametrise the freedom in choosing a representation
of the zero mode quantum algebra in the presence of non-trivial topology. One
consequence would appear to be that the values of such quantum degrees of
freedom, in other words of the associated topological background fields, cannot
be determined by the nonperturbative string dynamics.Comment: 1+10 pages, no figure
Unconventional antiferromagnetic correlations of the doped Haldane gap system YBaNiZnO
We make a new proposal to describe the very low temperature susceptibility of
the doped Haldane gap compound YBaNiZnO. We propose a new
mean field model relevant for this compound. The ground state of this mean
field model is unconventional because antiferromagnetism coexists with random
dimers. We present new susceptibility experiments at very low temperature. We
obtain a Curie-Weiss susceptibility as expected
for antiferromagnetic correlations but we do not obtain a direct signature of
antiferromagnetic long range order. We explain how to obtain the ``impurity''
susceptibility by subtracting the Haldane gap contribution to
the total susceptibility. In the temperature range [1 K, 300 K] the
experimental data are well fitted by . In the temperature range [100 mK, 1 K] the experimental data are
well fitted by , where increases with
. This fit suggests the existence of a finite N\'eel temperature which is
however too small to be probed directly in our experiments. We also obtain a
maximum in the temperature dependence of the ac-susceptibility which
suggests the existence of antiferromagnetic correlations at very low
temperature.Comment: 19 pages, 17 figures, revised version (minor modifications
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