The forthcoming two-satellite GMES Sentinel-1 constellation is expected to render systematic surface soil moisture retrieval at 1 km resolution using C-band SAR data possible for the first time from space. Owing to the constellation's foreseen coverage over the Sentinel-1 Land Masses acquisition region-global approximately every six days, nearly daily over Europe and Canada depending on latitude-in the high spatial and radiometric resolution Interferometric Wide Swath (IW) mode, the Sentinel-1 mission shows high potential for global monitoring of surface soil moisture by means of fully automatic retrieval techniques. This paper presents the potential for providing such a service systematically over Land Masses and in near real time using a change detection approach, concluding that such a service is-subject to the mission operating as foreseen-expected to be technically feasible. The work presented in this paper was carried out as a feasibility study within the framework of the ESA-funded GMES Sentinel-1 Soil Moisture Algorithm Development (S1-SMAD) project.
We tackle the problem of jointly increasing the spatial resolution and apparent measurement accuracy of an input low-resolution, noisy, and perhaps heavily quantized depth map. In stark contrast to earlier work, we make no use of ancillary data like a color image at the target resolution, multiple aligned depth maps, or a database of highresolution depth exemplars. Instead, we proceed by identifying and merging patch correspondences within the input depth map itself, exploiting patchwise scene self-similarity across depth such as repetition of geometric primitives or object symmetry. While the notion of 'single-image' super resolution has successfully been applied in the context of color and intensity images, we are to our knowledge the first to present a tailored analogue for depth images. Rather than reason in terms of patches of 2D pixels as others have before us, our key contribution is to proceed by reasoning in terms of patches of 3D points, with matched patch pairs related by a respective 6 DoF rigid body motion in 3D. In support of obtaining a dense correspondence field in reasonable time, we introduce a new 3D variant of PatchMatch. A third contribution is a simple, yet effective patch upscaling and merging technique, which predicts sharp object boundaries at the target resolution. We show that our results are highly competitive with those of alternative techniques leveraging even a color image at the target resolution or a database of high-resolution depth exemplars.
KurzfassungDie Erkenntnis, dass wir Linien, von denen wir wissen, dass sie tatsächlich im Raum parallel sind, als Linien wahrnehmen, die scheinbar zu einem gemeinsamen Fluchtpunkt konvergieren, hat zu Techniken geführt, mit denen Künstler einen glaubwürdigen Eindruck von Perspektive vermitteln können. Dies führte später auch zu Ansätzen, mit denen die zugrundeliegende Geometrie von Bildern -oder in der Tat auch von Gemälden mit korrekter Perspektive -extrahiert werden kann. In dieser Arbeit beschäftigen wir uns mit der Extraktion von Fluchtpunkten mit dem Ziel, die Rekonstruktion urbaner Szenen zu vereinfachen. Im Gegensatz zu den meisten Methoden zur Extraktion von Fluchtpunkten, extrahiert die unsere eine Konstellation von Fluchtpunktenüber mehrere Ansichten hinweg, anstatt nur in einem einzigen Bild. Durch das Verwenden eines starken Orthogonalitätskriteriums in jeder Ansicht, einer optimalen Berechnung von Segmentschnittpunkten und einem neuartigen Dreibein-Ausrichtungsverfahren, erlaubt unser Ansatz die Extraktion von Ergebnissen, die eine nahe Approximation der dominanten drei paarweise orthogonalen Orientierungen typischer urbaner Szenen darstellen. Dementsprechend kann unser Ansatz als wesentliche Verfeinerung der Methode von Sinha et al. bezeichnet werden.
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