Issues in Replication and Stability of Least-cost Path Calculations

Abstract

An important and frequently used tool in archaeological spatial analysis is least-cost path (LCP) analysis to compute routes connecting a set of targets. The outcome depends on the cost model chosen and the topographic data used. A slope-dependent cost model requires a digital elevation model (DEM) that should reflect the landscape in the past. It is often impossible to reconstruct the past terrain, and modern high-resolution elevation data results in problematic storage requirements and computation times. This article presents a case study that explores issues in replication and stability of LCP calculations for pairs of targets that are close to known old trade routes. A large number of cost models is tested based on two topographic data sets, including DEMs of two different resolutions (25 m and 50 m). The cost models use six different slope-dependent cost functions suggested by various authors for pedestrian movement. Moreover, a slope-dependent cost function is applied that results in LCPs including hairpin curves if the slope exceeds a predefined critical value. It is shown that the best-performing LCP sets for the two topographic data sets are closely related but not identical. Moreover, reasons for the failure of LCP reconstructions for some old route sections are discussed.

Keywords

• Reproducibility
• Digital Elevation Models
• Least-cost paths