Changes between Version 10 and Version 11 of Processing/atmosphericcorrection


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Timestamp:
Apr 13, 2017 10:12:22 AM (6 weeks ago)
Author:
dac
Comment:

Added image (external link for now until wiki upload is fixed).

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  • Processing/atmosphericcorrection

    v10 v11  
    11= Atmospheric Correction =
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    3 This page is designed to give information on atmospheric correction of NERC-ARF hyperspectral data and also what needs to be done before and during data collection.
     3This page is designed to give general information on atmospheric correction of NERC-ARF hyperspectral data and also what needs to be done before and during data collection. For more specific guidance please contact NERC-ARF. If you are planning to collect field spectra it is highly recommended you attend one of the NERC Field Spectroscopy Facility (FSF) courses, even if you are not borrowing FSF equipment. Details are posted on the FSF site (http://fsf.nerc.ac.uk/).
    44
    55== Information on collection of field spectra ==
     
    1919* always record time correctly (check the system and instrument clocks are correct), record time zone and daylight savings time etc.
    2020
    21 
    2221=== Prior to the survey ===
    2322
    2423* Test the instruments - both to check that they are working and to give you practice in using them. Ideally attend training courses such as that offered by the Field Spectroscopy Facility (FSF), this is a requirement if you borrow instruments from FSF.
    25 * Plan the survey - identify suitable targets before the survey day, either by visiting the site in person or using online or offline map data. Save as much time as possible so that when the survey day arrives you can spend your time collecting measurements. Only consider targets within the area of the remote sensing survey.
     24* Plan the survey - identify suitable targets / locations to deploy targets before the survey day, either by visiting the site in person or using online or offline map data. Save as much time as possible so that when the survey day arrives you can spend your time collecting measurements. Only consider targets within the area of the remote sensing survey.
    2625* If your survey site is accessible and time permits, it is a good idea to do a "dry-run" a few days before hand to identify any potential problems.
    2726* Consider both 'bright' and 'dark' targets, especially if one wants to perform a vicarious calibration.
     
    4746**Calibration Targets**
    4847
    49 NERC-ARF and FSF have calibration targets available for use. When laid out the targets should be approximately 8 x the ground pixel size.
     48NERC-ARF and FSF have calibration targets available for use if it is possible and practical to deploy them. When laid out the targets should be approximately 8 x the ground pixel size.
    5049
    51 With positioning the targets there are a few things that need to be considered.
     50When positioning the targets there are a few things that need to be considered.
    5251
    5352* The targets should be separated by approximately the same dimensions as the target, if not greater.
     
    5554* The white target normally needs a black target underneath it to prevent the underlying surface from showing through. Ideally this target should also be the last in any sequence so that any saturation effects (with subsequent recovery of the detector) do not impact other targets.
    5655* Adjacency effects are key. The large targets should minimise this but it becomes relevant for small targets. This is the impact of a strong spectral signal at the edge of the FOV. A classic example is vegetation. The effect can be minimised / eliminated if the targets are placed on a spectrally inert surface. Asphalt is normally quite good. Of course this needs to be spectrally inert for all the bands which you wish to use. 
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     57[[Image(https://nerc-arf-dan.pml.ac.uk/files/atsc_targets.jpg, align=center)]]
    5758
    5859== Available software ==