The purpose of contouring is to identify areas on a surface or contour chart that have like contour values. On a surface chart, the contour data is the elevation data itself. In such a chart, contour bands are painted upon the surface along areas within given elevation ranges while contour lines are striped along areas at specific elevations.

Basic contour information is contained in an array of contour attributes each of which define a contour band or line. Each element in the array consists of a contour value, brush for contour bands, pen for contour lines, and an optional label which is used to identify the contour element in a contour legend.

When displaying contour bands on a chart, areas on the chart whose contour values lie directly beneath a given elements value (but above the preceding elements value) are filled using that elements brush. When displaying contour lines on a chart, areas on the chart whose contour values exactly match a given elements value are striped using that elements pen.

You can use the Contour tab to set the types of contour you want to display on your chart. The available contour types are: