APPENDIX B: EXPLANATION OF CONTOUR PLOTS
The data from this study were partly displayed in the form
of contour plots. This type of graph, commonly used in land elevation maps, is used to
display three-dimensional information. The coordinates axes represent two of the
dimensions. Here, those were the X and Y coordinates of the points. The third dimension is
used to represent the value of interest as a function of the X and Y location; in this
case, the error. Curves are created by connecting points of identical value. Interpolation
techniques allow for these lines to have a much higher resolution than the original data.
Interpretation of these graphs is similar to interpreting a land map. "Peaks"
and "valleys" are displayed as closed contour lines.