Search results for "interpolation."

Statistical Learning for End-to-End Simulations

2018

End-to-end mission performance simulators (E2ES) are suitable tools to accelerate satellite mission development from concet to deployment. One core element of these E2ES is the generation of synthetic scenes that are observed by the various instruments of an Earth Observation mission. The generation of these scenes rely on Radiative Transfer Models (RTM) for the simulation of light interaction with the Earth surface and atmosphere. However, the execution of advanced RTMs is impractical due to their large computation burden. Classical interpolation and statistical emulation methods of pre-computed Look-Up Tables (LUT) are therefore common practice to generate synthetic scenes in a reasonable…

Interpolation and Gap Filling of Landsat Reflectance Time Series

2018

Products derived from a single multispectral sensor are hampered by a limited spatial, spectral or temporal resolutions. Image fusion in general and downscaling/blending in particular allow to combine different multiresolution datasets. We present here an optimal interpolation approach to generate smoothed and gap-free time series of Landsat reflectance data. We fuse MODIS (moderate-resolution imaging spectroradiometer) and Landsat data globally using the Google Earth Engine (GEE) platform. The optimal interpolator exploits GEE ability to ingest large amounts of data (Landsat climatologies) and uses simple linear operations that scale easily in the cloud. The approach shows very good result…

Cubic Local Splines on Non-uniform Grid

2015

In this chapter, two types of local cubic splines on non-uniform grids are described: 1. The simplest variation-diminishing splines and 2. The quasi-interpolating splines. The splines are computed by a simple fast computational algorithms that utilizes a relation between the splines and cubic interpolation polynomials. Those splines can serve as an efficient tool for real-time signal processing. As an input, they use either clean or noised arbitrarily-spaced samples. On the other hand, the capability to adapt the grid to the structure of an object and minimal requirements to the operating memory are great advantages for off-line processing of signals and multidimensional data arrays.

An exponential spline interpolation for unequally spaced data points

1982

Norm continuity and related notions for semigroups on Banach spaces

1996

We find some conditions on a c0-semigroup on a Banach space and its resolvent connected with the norm continuity of the semigroup. We use them to get characterizations of norm continuous, eventually norm continuous and eventually compact semigroups on Hilbert spaces in terms of the growth of the resolvent of their generator.

Regularity of the inverse of a Sobolev homeomorphism in space

2006

Let Ω ⊂ Rn be open. Given a homeomorphism of finite distortion with |Df| in the Lorentz space Ln−1, 1 (Ω), we show that and f−1 has finite distortion. A class of counterexamples demonstrating sharpness of the results is constructed.

Embedding of Sobolev Spaces into Lipschitz Spaces

1989

The main result of the paper is that if Ω is a bounded uniform domain in ℝn and p>n, then the Sobolev space Wl, p(Ω) embeds continously into Cα(Ω), α = 1 - n/p.

Spatial Analysis, Cartography and Climate

2010

International audience

Quantification des hauteurs de neige et des températures de l'air à la surface d'un glacier : du terrain à l'interpolation, confrontation de méthodes

2009

Quantifying snow cover and surface air temperature on a glacier is usually based on point data. The density of point measures is dependent on the local context. Interpolation brings the opportunity to generate a continuous surface. This surface can be used to derive a global measure for the whole glacier. These measures (total snow water equivalent, average thermal state) are integrated in glaciological and hydrological equations. Interpolation also renders the spatial variations of processes and provides information on inaccessible or not-monitored zones. Using the example of an arctic glacier, several interpolation methods were tested and compared. These methods were applied to snow drill…

Versatile optimization-based speed-up method for autofocusing in digital holographic microscopy

2021

We propose a speed-up method for the in-focus plane detection in digital holographic microscopy that can be applied to a broad class of autofocusing algorithms that involve repetitive propagation of an object wave to various axial locations to decide the in-focus position. The classical autofocusing algorithms apply a uniform search strategy, i.e., they probe multiple, uniformly distributed axial locations, which leads to heavy computational overhead. Our method substantially reduces the computational load, without sacrificing the accuracy, by skillfully selecting the next location to investigate, which results in a decreased total number of probed propagation distances. This is achieved by…