Changes between Version 1 and Version 2 of Processing/atcor


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Timestamp:
Jun 29, 2010 12:51:53 PM (9 years ago)
Author:
benj
Comment:

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  • Processing/atcor

    v1 v2  
    1616 1. Click "Selected SENSOR". Click the button with the sensor name and select the sensor appropriate to the bandset used for the flight (check the header file for the number of bands). Select the appropriate calibration file when prompted.
    1717 1. Change the nadir pixel size as appropriate (see pixel size calculator at http://arsf-dan.nerc.ac.uk/pixelsize/pixelsize.html)
    18  1. Click "Select" next to "ATMOSPHERIC FILE". Select an atmosphere model as appropriate to the flight location and altitude.
    19  1. Click "VISIB. ESTIMATE". Enter the given visibility value in the "Visibility" box.
     18 1. Click "Select" next to "ATMOSPHERIC FILE". Select 'rural' and select the atmosphere with a water vapour value of 1.0 (*wv10*) with the altitude closest to that of the flight above the ground (note, not absolute altitude).
     19 1. Click "AEROSOL TYPE". Wait for the tool to run. When it completes it will present you with two values for each atmosphere type. The second is the visibility, the former is a measure of how good the agreement is with the data - a lower number is better. Check that "rura" (rural) is the best value, if it's not then change the atmospheric file to a different atmosphere model as appropriate depending on which one is best. Enter the appropriate visibility number in the "Visibility" box
     20 1. Click "VISIB. ESTIMATE". Check the number agrees with the previous step - if not don't worry but it may need to be changed later.
     21 1. Click "WATER VAPOR". Click on "Calculate interpolated atmospheric file(s)" (if you don't get this option, go back and re-select the same atmospheric file). Once it's finished, click OK. Leave all the options on the next screen as default and click Done.
     22 1. Click "Calculate Water Vapor Map". Wait for it to complete.
     23 1. Open the water vapour map calculated in the previous step in ENVI. Go to Basic Tools > Calculate Statistics, select the WV map, leave all settings as default and check the mean value. If the mean value is closer to 400 than to 1000, go back and change your atmospheric file in ATCOR to use a water vapour value of 0.4 (*wv04*) instead of 1 (similarly if it's higher).
    2024 1. Click "IMAGE PROCESSING". Leave all the options as default and click OK.
    2125  1. Leave all the water vapour options as default and click DONE
     26  1. If it tells you that the current visibility settings result in a high number of pixels with negative reflectance then change the visibility settings as it suggests.
    2227  1. Click "RUN Atmospheric Correction" - wait for it to complete.
    2328