# Resource: con_interval

Resource | con_interval |
---|---|

Overview | Specifies the contour interval to use in contouring grids. This can also be used to color code plotted data and vectors. |

Command Line | -ci=value |

Environment Variable | wxpconint |

Possible Values | A positive number |

Default Value | 0 |

This resource is used to specify the contour interval. When running the
contouring programs, this is the interval between contour lines. For filled
contours, this is the interval for each color region. For vector and data
plots, it's used to color the text, wind vectors and streamlines. 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 specified with the
**resrc: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
**resrc: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.

*Last updated October 2013*