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Updated: Dec 14, 2025

Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
Atmospheric Correction Inter-comparison eXercise
Georgia Doxani1, Eric Vermote2, Jean-Clause Roger2,3
1SERCO SpA c/o European Space Agency ESA-ESRIN, Largo Galileo Galilei, 00044 Frascati, Italy.
Abstract:
The Atmospheric Correction Inter-comparison eXercise (ACIX) is an international initiative with the aim to analyse the Surface Reflectance (SR) products of various state-of-the-art atmospheric correction (AC) processors. The Aerosol Optical Thickness (AOT) and Water Vapour (WV) are also examined in ACIX as additional outputs of an AC processing. In this paper, the general ACIX framework is discussed; special mention is made of the motivation to initiate this challenge, the inter-comparison protocol and the principal results. ACIX is free and open and every developer was welcome to participate. Eventually, 12 participants applied their approaches to various Landsat-8 and Sentinel-2 image datasets acquired over sites around the world. The current results diverge depending on the sensors, products and sites, indicating their strengths and weaknesses. Indeed, this first implementation of processor inter-comparison was proven to be a good lesson for the developers to learn the advantages and limitations of their approaches. Various algorithm improvements are expected, if not already implemented, and the enhanced performances are yet to be investigated in future ACIX experiments.
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