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Directional Hemispherical Reflectance (Black Sky Albedo)

The directional hemispherical reflectance (DHR) is defined as the albedo of a target under direct illumination only.
Known also as black-sky albedo is, along with the white-sky albedo (or bi-hemispherical reflectance, BHR), a typical remote sensing product. It is related to th bidirectional reflectance factor (BRF) through the equation
$$DHR(\theta_i,\phi_i;2\pi)=\frac{1}{\pi} \int BRF(\theta_i,\phi_i;\theta_r,\theta_r) d\Omega_r$$ where the projected solid angle [sr] is given in terms of zenith ($\theta$) and azimuth ($\phi$) angles by $d\Omega = \sin\theta \cos\theta d\theta d\phi$.

Notice that within RAMI all incident and exiting radiation has to pass through a (virtual) planar reference surface of specified lateral dimension and elevation above the target, and oriented perpendicular to the underlying surface normal.
Simulations can be performed for all RAMI-V bands excluding GED. Sun geometries are the same as defined for brfpp and brfop measurements types, hence they depends on the specific scene (link or table again).

DHR: direct only
DHR: direct only
The reference plane
The reference plane.

Columns content

Content Format
directional hemispherical reflectance %.6f
standard deviation of dhr estimate* %.6f

*: if available, otherwise set to −1.000000.

0.123456	-1.000000