A cost surface can be thought of as a map of the costs of movement from one location to one or more destinations. Cost surfaces are usually generated as the first step in computing least-cost paths between locations. Although cost surfaces are typically represented in raster format, vector-based cost surfaces can be created, though these are more complex and difficult to compute than raster-based models. This entry focuses on cost surfaces represented as rasters. Cost surface maps are also known as cost-of-passage maps, accumulated cost surface maps, and friction surfaces or friction maps.

To create a cost surface within a GIS, it is necessary to consider the following: the mode of transport or movement, the currency used to calculate costs of movement, attributes of the landscape ...