Resource: con_interval

This resource is used to specify the contour interval.  When running the contouring programs, this value is prompted for if not specified. For plotting, this will specify the interval for coloring the plotted and vector data. The same algorithm for determining the value of the color fill contours is used for coloring data values. Whereas, the maximum and minimum values of a grid are known, these values are not known when plotting data.  Thus, the interval is specified and the base value is assumed to be 0 unless otherwise specified (see con_base resource).

Automated Interval (interval=0)

If the value is 0, the program will compute a reasonable value which is based on the number of values in the color fills (see color_fill resource).

   interval ~= (max-min)/num_colors

This value is rounded up to the nearest whole number.  This is also based on the range of data so if the range is less than 1, the program will make the resulting contour interval a fractional value.