Background

Many problems can be solved using a cost surface, including minimun distance computation. The function included in GRASS can compute the cost surface when the friction (the unit cost, that indicates the cost to move from one cell to a neighbour cell) do not depend on the direction.

For some problem this can not be assumed, as the cost problem is anisotropic. For these problem it is necessary to use different methods that take into account the direction of movement.

Here we describes briefly a new module to compute anisotropic cost surfaces and path using Grass.