# 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; $$θ_{SZ} = 90° - θ_{SE}$$

## Input

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

## Output

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