pybsm.metrics.functional.giqe5

pybsm.metrics.functional.giqe5(*, rer_1: float, rer_2: float, gsd: float, snr: float, elev_angle: float) → tuple[float, float, float]

NGA The General Image Quality Equation version 5.0. 16 Sep 2015. (originally published by https://gwg.nga.mil/) https://github.com/Kitware/pybsm/blob/main/docs/GIQE-5_for_Public_Release.pdf

This version of the GIQE replaces the earlier versions and should be used in all future analyses. See also “Airborne Validation of the General Image Quality Equation 5” https://opg.optica.org/ao/abstract.cfm?uri=ao-59-32-9978

Parameters:

  • rer_1 – relative edge response in two directions (e.g., along- and across- scan, horizontal and vertical, etc.); see also pybsm.metrics.functional.giqe5_RER. (unitless)

  • rer_2 – relative edge response in two directions (e.g., along- and across- scan, horizontal and vertical, etc.); see also pybsm.metrics.functional.giqe5_RER. (unitless)

  • gsd – image plane geometric mean ground sample distance (m), as defined for GIQE3; the GIQE 5 version of GSD is calculated within this function

  • snr – contrast signal-to-noise ratio (unitless), as defined for GIQE3

  • elev_angle – sensor elevation angle as measured from the target (rad), i.e. pi/2-nadir_angle; see pybsm.geospatial.nadir_angle for more information

Returns:

niirs :

a National Image Interpretability Rating Scale value (unitless)

gsd_w :

elevation angle weighted GSD (m)

rer :

weighted relative edge response (rer)

Raises:
ZeroDivisionError:

error raised when snr is 0

NOTE:

NIIRS 5 test case: rer_1=rer_2=0.35, gsd = 0.52832 (20.8 inches), snr = 50, elev_angle = np.pi/2. From Figure 1 in the NGA GIQE5 paper.