KOMPSAT-3/3A
KOMPSAT-3 and KOMPSAT-3A acquisitions are calibrated using the Orfeo Toolbox.
DN to Radiance
For the conversion from DN to spectral radiance (or ‘TOA radiance’) \(L \), the following formula is used :
\(L \) in \(W/m^2/steradians/micrometers\) with \(b\) being a band ID.
The gain and bias values are read from the acquisition metadata.
Radiance to TOA Reflectance
To convert TOA radiance to TOA reflectance, the following formula is used :
where :
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\(L(b)\) is the spectral radiance for band b
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\(pi\) is the famous mathematical constant
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\(d\) is the earth-sun distance (in astronomical units) and depends on the acquisition’s day and month
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\(ESUN(b)\) is the mean TOA solar irradiance (or solar illumination) in \(W/m^2/micrometers\)
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\(θ\) is the solar zenith angle in degrees.
The values for the ESUN are provided in the tables below:
KOMPSAT-3
Band | Nominal
bandpass (nm) |
50% bandpass (nm) | Center (nm) | Bandwidth
(nm) |
ESUN |
Blue | 450 - 520 | 445.6 – 532.3 | 489.0 | 86.7 | 1970.281 |
Green | 520 - 600 | 511.9 – 606.1 | 559.0 | 94.2 | 1814.155 |
Red | 630 - 690 | 633.1 – 702.8 | 668.0 | 69.7 | 1516.303 |
NIR | 760 - 900 | 756.0 – 932.2 | 844.1 | 176.2 | 1024.850 |
KOMPSAT-3A
Band | Nominal
bandpass (nm) |
50% bandpass (nm) | Center (nm) | Bandwidth
(nm) |
ESUN |
Blue | 450 - 520 | 445.6 – 532.3 | 489.0 | 86.7 | 2001 |
Green | 520 - 600 | 511.9 – 606.1 | 559.0 | 94.2 | 1875 |
Red | 630 - 690 | 633.1 – 702.8 | 668.0 | 69.7 | 1525 |
NIR | 760 - 900 | 756.0 – 932.2 | 844.1 | 176.2 | 1027 |
Input
The input is an ingested KOMPSAT-3 or KOMPSAT-3A, see details here.
Output
The output is a STAC item geojson ... including the assets ...
References
RW01 - OTB Optical calibration