The Minnaert function is a photometric function used to interpret astronomical observations[1][2] and remote sensing data for the Earth.[3] It was named after the astronomer Marcel Minnaert. This function expresses the radiance factor (RADF) as a function the phase angle (), the photometric latitude () and the photometric longitude ().
where is the Minnaert albedo, is an empirical parameter, is the scattered radiance in the direction , is the incident radiance, and
The phase angle is the angle between the light source and the observer with the object as the center.
The assumptions made are:
- the surface is illuminated by a distant point source.
- the surface is isotropic and flat.
Minnaert's contribution is the introduction of the parameter , having a value between 0 and 1,[4] originally for a better interpretation of observations of the Moon. In remote sensing the use of this function is referred to as Minnaert topographic correction, a necessity when interpreting images of rough terrain.
References
[edit]- ^ Chanover, N.J.; Anderson, C.M.; McKay, C.P.; Rannou, P.; Glenar, D.A.; Hillman, J.J.; Blass, W.E. (2003). "Probing Titan's lower atmosphere with acousto-optic tuning". Icarus. 163 (1): 150–163. Bibcode:2003Icar..163..150C. doi:10.1016/S0019-1035(03)00075-7.
- ^ Soderblom, J.; Belliii, J.; Hubbard, M.; Wolff, M. (2006). "Martian phase function: Modeling the visible to near-infrared surface photometric function using HST-WFPC2 data". Icarus. 184 (2): 401–423. Bibcode:2006Icar..184..401S. doi:10.1016/j.icarus.2006.05.006.
- ^ Blesius, L.; Weirich, F. (2005). "The use of the Minnaert correction for land-cover classification in mountainous terrain". International Journal of Remote Sensing. 26 (17): 3831–3851. Bibcode:2005IJRS...26.3831B. doi:10.1080/01431160500104194. S2CID 129750287.
- ^ Minnaert, M. (1941). "The reciprocity principle in lunar photometry" (PDF). The Astrophysical Journal. 93: 403. Bibcode:1941ApJ....93..403M. doi:10.1086/144279.