An overview of the Legacy Distance toolset

Legacy:

This is a deprecated toolset. The Distance toolset provides enhanced functionality or performance.

The Legacy Distance tools allow you to access the distance analysis tools available in earlier releases of ArcGIS. These tools perform analysis that accounts for either straight-line (Euclidean) distance or weighted distance. Distance can be weighted by a simple cost (friction) surface or in ways that account for vertical and horizontal restrictions to movement. The Legacy Distance tools use the original method of computing distance from earlier releases. To take advantage of the more accurate distance calculations now available, use the distance tools outside of the Legacy toolset.

The two main ways of performing distance analysis with the ArcGIS Spatial Analyst extension is with the Euclidean distance and the cost-weighted distance tools.

The Euclidean Distance tool measures the straight-line distance from each cell to the closest source; the source identifies the objects of interest, such as wells, roads, or a school. The distance is measured from cell center to cell center. Not only can you determine the distance each cell is to the closest source, you can also calculate for each cell the direction with Euclidean Direction and determine the closest source with Euclidean Allocation.

• Learn more about Euclidean distance

The Cost Distance (or cost-weighted distance) tool modifies Euclidean distance by equating distance as a cost factor, which is the cost to travel through any given cell. For example, it may be a shorter distance to climb over the mountain to the destination, but it is quicker to walk around it. The Cost Allocation tool identifies the nearest (or least costly) source cell based on accumulated travel cost. The Cost Back Link tool provides a road map, identifying the route to take from any cell, along the least-cost path, back to the nearest source.

• Learn more about cost distance analysis

In addition to a single cost variable, vertical and horizontal restrictions to movement can be incorporated into your analysis with the Path Distance, Path Distance Allocation, and Path Distance Back Link tools.

• Learn more about path distance analysis

Once you have performed the cost distance analysis, creating distance and direction rasters, you can compute the least-cost (or shortest) path from a chosen destination to your source location with the Cost Path and Cost Path as Polyline tools. The cost path travels from the destination to the source in what is guaranteed to be the least expensive route relative to the cost units defined by the original cost raster. Using two cost rasters instead of a linear path, you can use the Corridor tool to determine a collection of cells that do not exceed a specified cost.

• Learn more about least-cost path and least-cost corridor

The following table lists the available tools and provides a brief description of each.

Tools in the Legacy Distance toolset

Tool	Description
Corridor	Calculates the sum of accumulative costs for two input accumulative cost rasters.
Cost Allocation	Calculates, for each cell, its least-cost source based on the least accumulative cost over a cost surface.
Cost Back Link	Defines the neighbor that is the next cell on the least accumulative cost path to the least-cost source.
Cost Connectivity	Produces the least-cost connectivity network between two or more input regions.
Cost Distance	Calculates the least accumulative cost distance for each cell from or to the least-cost source over a cost surface.
Cost Path	Calculates the least-cost path from a source to a destination.
Cost Path as Polyline	Calculates the least-cost path from a source to a destination as a line feature.
Euclidean Allocation	Calculates, for each cell, the nearest source based on Euclidean distance.
Euclidean Back Direction	Calculates, for each cell, the direction, in degrees, to the neighboring cell along the shortest path back to the closest source while avoiding barriers.
Euclidean Direction	Calculates, for each cell, the direction, in degrees, to the nearest source.
Euclidean Distance	Calculates, for each cell, the Euclidean distance to the nearest source.
Path Distance	Calculates, for each cell, the least accumulative cost distance from or to the least-cost source, while accounting for surface distance along with horizontal and vertical cost factors.
Path Distance Allocation	Calculates the least-cost source for each cell based on the least accumulative cost over a cost surface, while accounting for surface distance along with horizontal and vertical cost factors.
Path Distance Back Link	Defines the neighbor that is the next cell on the least accumulative cost path to the least-cost source, while accounting for surface distance along with horizontal and vertical cost factors.