Landsat-8

DN to Reflectance

Reflective band DN’s are converted to TOA reflectance using the rescaling coefficients in the MTL file:

\[ R(b)′= M_b \times DN + A_b \]

where:

\(R(b)'\) is the Top of Atmosphere planetary reflectance, without correction for solar angle.

Note that \(R(b)'\) does not contain a correction for the sun angle.

\(M_b\) is the band-specific multiplicative rescaling factor from the metadata (REFLECTANCE_MULT_BAND_x, where x is the band number)
\(A_b\) is the band-specific additive rescaling factor from the metadata (REFLECTANCE_ADD_BAND_x, where x is the band number)

Top of Atmosphere reflectance with a correction for the sun angle is then:

\[ R(b) = R(b)' \times cos(θ_{SZ}) = R(b)' \times sin(θ_{SE}) \]

where:

\(R(b)\) is the TOA planetary reflectance
\(θ_{SE}\) is the local sun elevation angle. The scene center sun elevation angle in degrees is provided in the metadata (SUN_ELEVATION).
\(θ_{SZ}\) is the local solar zenith angle; \(θ_{SZ} = 90° - θ_{SE}\)

The input is an ingested Landsat-8, see details here.

The output is a STAC item geojson ... including the assets ...