Geography Reference
In-Depth Information
practicalities of managing file sizes and the need for reasonably accurate data.
Larger files allowed clear image processing, however file handling was limited
by available hardware (Figure 2).
Our study began by developing a geographical surface model of the region
using ArcView 3.2 software and its accompanying 3-D Analyst tool (Figure
3). This model allowed us to geo-spatially analyse slopes in an extensive
landscape and identify potential transport corridors without the need for
extensive individual pathway calculations. The surface model was developed
using current topographical maps of the area. Without ground-truthing, our
interpretation and digitising is subject to the tolerances and accuracy of the
source survey maps. Error when using a Digital Elevation Model (DEM) and
the associated slope tools in the GIS was expected during this assemblage
process (Hageman and Bennett, 2000). The digitising process itself was
understood to be another potential source for errors, which arise from
interpretation. This was a problem that was noted by others as are strategies to
minimize the problem (Bolstad, et al., 1990, Morad, et al., 1996).
Figure 1. Preliminary digitising using INEGI survey map 1:50000 (L. C. Hazell).
