UK-DMC-2
UK-DMC-2 acquisitions are calibrated using the Orfeo Toolbox.
DN to Radiance
The UK-DMC-2 product handbook provides the formula below to convert the DN into radiance:
For the conversion from \(DN\) (for Digital Numbers) to spectral radiance (or ‘TOA radiance’) \(L \), the following formula is used :
As such, the calibration uses:
and
\(L \) in \(W/m^2/steradians/micrometers\) with \(b\) being a band ID.
Radiance to 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 \(ESUN(b)\) are provided in the table below:
Common band name | Mean TOA solar irradiance |
nir | 1036 |
red | 1561 |
green | 1811 |
Input
The input is an ingested UK-DMC-2, see details here.
Output
The output is a STAC item geojson ... including the assets ...
References
RW01 - OTB Optical calibration