Standard edge detection operators such as the Laplacian of Gaussian and the gradient of Gaussian can be used to track contours in image sequences. When using edge operators, a contour, which is determined on a frame of the sequence, is simply used as a starting contour to locate the nearest contour on the subsequent frame. However, the strategy used to look for the nearest edge points may not work when tracking contours of non isolated gray level discontinuities. In these cases, strategies derived from the optical flow equation, which look for similar gray level distributions, appear to be more appropriate since these can work with a lower frame rate than that needed for strategies based on pure edge detection operators. However, an optical flow strategy tends to propagate the localization errors through the sequence and an additional edge detection procedure is essential to compensate for such a drawback. In this paper a spatio-temporal intensity moment is proposed which integrates the two basic functions of edge detection and tracking.
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http://dx.doi.org/10.1109/TPAMI.2015.2478438 | DOI Listing |
Braz J Biol
January 2025
Near East University, Operational Research Center in Healthcare, Mersin, Turkey.
Amidst the ongoing COVID-19 pandemic, the imperative of our time resides in crafting stratagems of utmost precision to confront the relentless SARS-CoV-2 and quell its inexorable proliferation. A paradigm-shifting weapon in this battle lies in the realm of nanoparticles, where the amalgamation of cutting-edge nanochemistry begets a cornucopia of inventive techniques and methodologies designed to thwart the advances of this pernicious pathogen. Nanochemistry, an artful fusion of chemistry and nanoscience, provides a fertile landscape for researchers to craft innovative shields against infection.
View Article and Find Full Text PDFSci Adv
January 2025
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
The circumstellar liquid-water habitable zone guides our search for potentially inhabited exoplanets but remains observationally untested. We show that the inner edge of the habitable zone can now be mapped among exoplanets using their lack of surface water, which, unlike the presence of water, can be unambiguously revealed by atmospheric sulfur species. Using coupled climate-chemistry modeling, we find that the observability of sulfur gases on exoplanets depends critically on the ultraviolet (UV) flux of their host star, a property with wide variation: Most M-dwarfs have a low UV flux and thereby allow the detection of sulfur gases as a tracer of dry planetary surfaces; however, the UV flux of Trappist-1 may be too high for sulfur to disambiguate uninhabitable from habitable surfaces on any of its planets.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
University of Tokyo, Institute for Solid State Physics, Kashiwa, Chiba 277-8581, Japan.
Non-Hermiticity gives rise to distinctive topological phenomena absent in Hermitian systems. However, connection between such intrinsic non-Hermitian topology and Hermitian topology has remained largely elusive. Here, considering the bulk and boundary as an environment and system, respectively, we demonstrate that anomalous boundary states in Hermitian topological insulators exhibit non-Hermitian topology.
View Article and Find Full Text PDFScientific-grade spectrometers with high hyperspectral resolution and high spectral accuracy are desirable in miniaturized optical systems to maintain stable and real-time spectral sampling. Fourier transform spectrometers that utilize high-precision moving mirrors generally struggle to enhance their miniaturization and stable real-time performance. A static infrared spectral measurement method is proposed that uses micro/nano-optical devices as the core of static interference and lightweight imaging.
View Article and Find Full Text PDFOptical metasurfaces offer significant advantages in enhancing the speed, efficiency, and miniaturization of imaging systems. However, most existing metasurfaces are limited to static functionalities and lack reconfigurability, which is a key feature for practical applications in dynamic environments. In this work, we demonstrate a reconfigurable optical metasurface capable of switching between two distinct imaging functions (edge detection and bright-field imaging) within the visible spectrum.
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