ACIX I: CEOS-WGCV Atmospheric Correction Inter-comparison Exercise
1st Workshop

Minimize Background

ACIX is an international collaborative initiative to inter-compare a set of atmospheric correction (AC) processors for high-spatial resolution optical sensors. The exercise will focus on Landsat-8 and Sentinel-2 imagery over a set of test areas. The inter-comparison of the derived Bottom-of-Atmosphere (BOA) products is expected to contribute to the understanding of the different uncertainty contributors and help in improving the AC processors.



The free and open data access policy to Landsat-8 and Sentinel-2 satellite imagery has stimulated the development of atmospheric correction (AC) processors for generating Bottom-of-Atmosphere (BOA) products. Several entities have started to generate (or plan to generate in the short term) BOA reflectance products at global scale for Landsat-8 and Sentinel-2 missions. To this end, NASA and the European Space Agency are organizing this exercise on AC processors inter-comparison. The results of the exercise are expected to point out the strengths and weaknesses, as well as communalities and discrepancies of various AC processors, in order to suggest and define ways for their further improvement.

Minimize Objectives and Expected Outcomes

The exercise aimed to bring together the developers of the available AC processors, who were invited to generate the corresponding BOA products. The input data were Landsat-8 and Sentinel-2 imagery of various test sites, i.e. coastal, agricultural, snow/artic areas and deserts. A common and harmonised inter-comparison procedure was agreed and followed by all the participants.


Objective of the 1st Workshop

To discuss and elaborate concepts, protocols and guidelines for the inter-comparison and validation of BOA products

Expected Outcomes of the 1st Workshop

  • Description of concept, protocols and procedures for inter-comparing and validating products
  • Definition of the ACIX protocol
Minimize Programme

You can find the Programme of the 1st ACIX workshop  here

Minimize Schedule and Deadlines

The Atmospheric Correction Inter-comparison Exercise was performed in three phases:

  1. Definition of the inter-comparison protocol: The participants were invited to propose a protocol for the AC processors inter-comparison. The number and type of the test sites, the number of scenes and the metrics for models inter-comparison were proposed before the 1st ACIX workshop. All the proposals were discussed in the workshop and all participants agreed on the final inter-comparison procedure.
  2. Application of the AC processors: The participants applied their AC schemes on the test cases keeping the processing parameters constant. The results were submitted for analysis (3rd phase) to ACIX coordinators.
  3. Analysis of the results: The ACIX coordinators analysed the submitted results from all participants and assessed the inter-comparison outputs based on the agreed metrics. All the results were announced to participants prior to the 2nd ACIX workshop, where they were presented and discussed.

1st Workshop Announcement

25 January 2015

1st Workshop Registration Deadline

15 March 2016

1st Workshop Preliminary programme

30 April 2016

Proposals for AC inter-comparison protocol Deadline

31 May 2016

1st Workshop of CEOS-WGCV Atmospheric Correction Inter-comparison Exercise

21-22 June 2016


Minimize Registration
Minimize Venue
Venue and accommodation information are available here
Minimize Organisation
Local Organiser    Organisation committee
Jean-Claude Roger, University of Maryland (USA)
Eric Vermote, NASA/GSFC (USA)
Georgia Doxani, Serco and ESA/ESRIN (Italy)
Ferran Gascon, ESA/ESRIN (Italy)
Jean-Claude Roger, University of Maryland (USA)
Eric Vermote, NASA/GSFC (USA)



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