Changes between Version 2 and Version 3 of Processing/Py6S_vs_Hyperspectral


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Timestamp:
Oct 21, 2015 10:21:45 AM (4 years ago)
Author:
asm
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  • Processing/Py6S_vs_Hyperspectral

    v2 v3  
    1515=== Running Py6S for hyperspectral delivery check ===
    1616
    17 You can plot the at-sensor radiance spectra recorded by hyperspectral sensonr and compare it to the at-sensor py6s model using the script check_fenix_spectra_py6s.py. This procedure should be done during the hyperespectral delivery check.
     17You can plot the at-sensor radiance spectra recorded by hyperspectral sensor and compare it to the at-sensor py6s model using the script check_fenix_spectra_py6s.py. This procedure should be done during the hyperespectral delivery check.
    1818
    19 The simplest version of the script looks for a ramdom vegetation pixel at nadir and plots its spectra recorded by the Fenix sensor versus the predefined py6s vegetation type without atmospheric correction.
     19The simplest version of the script looks for a random vegetation pixel at nadir and plots its spectra recorded by the Fenix sensor versus the predefined py6s vegetation type without atmospheric correction.
    2020
    2121Go to delivery project directory that you want to check. Example:
     
    4141
    4242
    43 If you want to run the model with different setings, click here for more advanced techniques such as:
    44   -Plot sepectra for only one flightline in a directory with several ones. Or a specific flightline with different names on IGM, NAV and level1b.
     43If you want to run the model with different settings, click here for more advanced techniques such as:
     44  -Plot spectra for only one flightline in a directory with several ones. Or a specific flightline with different names on IGM, NAV and level1b.
    4545  -Chose a pixel by its given (lat,lon).
    4646  -Chose a pixel by its position on the grid (x,y).
     
    5454Py6S has several parameters needed to run the model. For this script, ARSF have selected the most convenient ones for our use but do not expect perfect match of the hyperspectral spectra recorded from our sensor against the Py6S. A more detailed explanation about Py6S parameters and settings used by ARSF can be found here
    5555
    56 Both curves (Fenix and Py6S) should match general features. The peaks and depression (reflecfance-absorption) caused by vegetation have to match and there should be no other spikes on the Fenix spectra that does not match the Py6s. However, note that it is probably to have a spike on some Fenix spectra flightlines on the bands around band 349, close to 900-950 nm. This is caused by the shift on the SWIR bands detected on on October 2014 and those pixels are listed as bad pixels, therefore the spectra recorded by Fenix is correct. You can find a picture ilustrating this issue which also suggest the type of spike you have to look for when they are not on the overlapping region.
     56Both curves (Fenix and Py6S) should match general features. The peaks and depression (reflecfance-absorption) caused by vegetation have to match and there should be no other spikes on the Fenix spectra that does not match the Py6s. However, note that it is probably to have a spike on some Fenix spectra flightlines on the bands around band 349, close to 900-950 nm. This is caused by the shift on the SWIR bands detected on on October 2014 and those pixels are listed as bad pixels, therefore the spectra recorded by Fenix is correct. You can find a picture illustrating this issue which also suggest the type of spike you have to look for when they are not on the overlapping region.
    5757
    5858Under_picture: Figure shows Fenix vs Py6S. Both spectra matches except for a Fenix spike close to 950 nm. No other spikes or depressions like which does not match the Py6S model should be found outside that region.