It is important to realize that the depiction of edges in raster images is fundamentally constrained by the lattice grid structure. Consequently, raster images portray lines in stair-step fashion. The result is an upward bias in the measurement of edge length; that is, the measured edge length is always more than the true edge length. The magnitude of this bias depends on the grain or resolution of the image (i.e., cell size), and the consequences of this bias with regards to the use and interpretation of edge-based metrics must be weighed relative to the phenomenon under investigation.