Modeling visibility through vegetation

The calculation of visibility patterns associated with past monuments and sites is an important element in modern landscape archaeology. These types of investigations have been limited by the inability of current viewshed routines to incorporate vegetation information. The following paper presents a new viewshed algorithm aimed at calculating the probability of locations being visible in the presence of vegetation. To this day, little work has been done to address this limitation, a notable exception is Dean's Permeability Index Model (1997 Dean, D. J. 1997. Improving the accuracy of forest viewsheds using triangulated networks and the visual permeability method.. Canadian Journal of Forest Research, 27: 969–977. Crossref] , Google Scholar]). A review of Dean's model is provided here in the light of the new proposed algorithm. The new algorithm is based on mathematical principles found in Beer–Lambert's Attenuation Law, a physics law governing the attenuation of light through a medium. In addition to common viewshed parameters, the routine requires a 3D model of a tree/plant and a layer indicating the spatial distribution and density of vegetation on the landscape. The possibility of varying both, the spatial and density distribution of tree/plants, and the three‐dimensional model representing vegetation makes the model well suited to investigate the impact that vegetation may have on visibility patterns.