Added topo.dist parameter to movecost(): when set to TRUE, the function calculates accumulated cost using topographic (surface) distance rather than planar (horizontal) distance. This accounts for the additional distance incurred when traversing sloped terrain, providing more realistic walking-time estimates in mountainous areas. The correction is calculated as surface distance = planar distance times the square root of (1 + slope squared). For example, on a 30% slope, surface distance is approximately 4.4% greater than planar distance; on a 50% slope, approximately 11.8% greater.
The topo.dist parameter works with all available cost functions, though it is particularly recommended for time-based hiking functions. Users should exercise caution when applying it to metabolic energy expenditure functions, as these were typically derived empirically using planar distance measurements.
Added detailed documentation section explaining the topographic distance methodology, its mathematical basis, and guidance on appropriateness for different cost function types.
Propagated the new topo.dist parameter to all wrapper functions that rely on movecost() as internal workhorse: movealloc(), movebound(), movecomp(), movecorr(), movenetw(), and moverank(). Users can now control whether topographic (surface) or planar distance is used directly from each wrapper. The default value (topo.dist = FALSE) preserves backward compatibility, so existing code continues to behave exactly as in version 2.1.