Permeability, rather than being based on individual species movements, is a measure of landscape structure, incorporating the hardness of barriers, the connectedness of natural cover, and the arrangement of land uses. Permeability is a surface that reveals the implications of the physical landscape structure with respect to the continuous flow of natural processes, including not only the dispersal and recruitment of plants and animals, but the rearrangement of existing communities.  Local connectedness starts with a focal cell and measures the resistance to flows outward in all directions of the cell's local neighborhood.  Regional flow patterns look at the broader flow patterns across the entire region, measuring how these patterns become slowed, redirected, or channeled due to the spatial arrangement of impediments. 

Permeability data and documentation is taken from a larger report, "Resilient Sites for Terrestrial Conservation in the Northeast and Mid-Atlantic Region", which can be downloaded here.