The multi-scale analytical canopy (MAC) model deals with an arbitrary number of scales of canopy organisation. The angular gap size distribution defined as the probability of a gap of length along the plane containing both view and illumination direction vectors is applied to describe the extent of the "hotspot" effect in a manner that includes all scales.
Reference
A multi-scale analytical canopy (MAC) reflectance model based on the angular second order gap size distribution
R. Fernandes R., Leblanc, S. G. and Simic, A., A multi-scale analytical canopy (MAC) reflectance model based on the angular second order gap size distribution (2003), IGARSS 2003, 2003 IEEE International Geoscience and Remote Sensing Symposium, Proceedings (IEEE Cat. No.03CH37477), 7 4431-4433, DOI: 10.1109/IGARSS.2003.1295537.
