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projects:earth_observation:sen2cor_processing_handbook [2024/12/06 09:47] – kymkiprojects:earth_observation:sen2cor_processing_handbook [2024/12/06 09:56] (current) – kymki
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-==== The Sen2cor Processing Handbook ====+==== The Sentinel 2 Data Processing Handbook ====
  
 This post is work in progress. You have been warned! This post is work in progress. You have been warned!
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     dates the individual lines in the recieved image to enable the exact capture time of each ISP within a predefined granule (geographic region) to be recorded,     dates the individual lines in the recieved image to enable the exact capture time of each ISP within a predefined granule (geographic region) to be recorded,
     packages Instrument Source Packets obtained from the satellite ground station network into granules     packages Instrument Source Packets obtained from the satellite ground station network into granules
 +    
 +== Level-0 Consolidated ==
 +
 +This intermediary product contains L-0 and all the meta-data required for subsequent L1 processing. These packets of data are compressed and stored. Like the L0 product L0C is not available to the public.
 +
 +== Level-1 A ==
 +
 +This processing step refers to the decompression of the L0C product and applies no processing beyond that.
 +
 +== Level-1 B ==
 +
 +   1.  Level-1B radiometric processing, including:
 +
 +    dark signal correction
 +    pixel response non-uniformity correction
 +    crosstalk correction
 +    defective pixels identification
 +    high spatial resolution bands restoration (de-convolution and de-noising)
 +    binning of the 60 m spectral bands.
 +
 +   2. Resampling on the common geometry grid for registration between the Global Reference Image (GRI) and the reference band (B4 by default).
 +   3. Collection of the tie-points from the two images for registration between the GRI and the reference band.
 +   4. Tie-points filtering for image-GRI registration: filtering of the tie-points over several areas. A minimum number of tie-points is required.
 +   5. Refinement of the viewing model using the initialised viewing model and and Ground Control Points (GCPs). The output refined model ensures registration between the GRI and the reference band.
 +   6. Level-1B imagery compression utilises the JPEG2000 algorithm.
 +   
 +== Level 1 ==
 +
 +‌‌Sentinel-2 MSI L1C data undergoes a number of pre-processing steps before it is ready for use. These steps include radiometric and geometric correction, atmospheric correction, and cloud and water masking.‌‌‌‌‌‌‌‌DEM https://sentinel.esa.int/web/sentinel/user-guides/sentinel-2-msi/definitions
 +
 +Radiometric correction is applied to adjust the data to account for variations in the instrument's sensitivity and to remove any effects of the atmosphere on the measured radiance.
 +
 +Geometric correction is applied to remove any distortion in the image caused by the satellite's motion and to project the data onto a consistent map projection.
 +
 +Atmospheric correction is applied to remove the effects of the atmosphere on the measured radiance. This step is necessary because the atmosphere can cause the measured radiance to be either higher or lower than the actual surface reflectance.
 +
 +Cloud and water masking is applied to identify and mask out any clouds or water bodies in the image. This step is necessary because clouds and water can interfere with the analysis of the data.
 +
 +Overall, the pre-processing steps applied to Sentinel-2 MSI L1C data are designed to correct for various factors that can affect the quality of the data and to make the data more consistent and usable for various applications.
 +
 +== Outlook and advice == 
 +
 +We recommend taking a parsimonious approach to preprocessing; correct the artifacts necessary for a particular application, but avoid unnecessary steps that may introduce additional artifacts without gaining additional value (Song et al. 2001, Riaño et al. 2003, Kennedy et al. 2009).
 +
 +Sources, further reading:
 +
 +    Young, Nicholas & Anderson, Ryan & Chignell, Stephen & Vorster, Anthony & Lawrence, Rick & Evangelista, Paul. 2017. A survival guide to Landsat preprocessing. Ecology. 98. 920-932. 10.1002/ecy.1730.
 +    Gyanesh Chander, Brian L. Markham, Dennis L. Helder. 2009. Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors, Remote Sensing of Environment, Volume 113, Issue 5, Pages 893-903,‌‌