WMS:Contour Options

The options used to generate contours can be edited by selecting the Contour Options command in the Display menu. Each object that can be contoured (i.e. DEMs, TINs, Grids, Flood Plains) has its own set of contour options. This means that you can have color filled contours for a DEM and linear contours on a TIN at the same time. The set of contour options you are editing is determined by either the current module and/or the display options dialog from which the contour options are activated. For 2D grids there is set of contour options associated with data set and the options of each data set can be specified by right-clicking on the data set folder from the Tree window, or by selecting an active data set and choosing the Contour Options command or Macro.

The items in the Contour Options dialog are as follows:

Data Set Information

The values shown in the upper left corner of the dialog correspond to the maximum and minimum values in the active data set (TIN, DEM, etc.). These values are useful when choosing an appropriate contour interval.

Contour Interval

Three Contour Interval options are available.

Contour Method

The options at the lower left of the dialog control how the contours are computed. Three contouring methods are available:

Normal Linear Contours

The default method is Normal linear contours and results in the contours being displayed as piece-wise linear strings.

Color Fill Between Contours

If the Color fill between contours button is selected, the region between adjacent contour lines is filled with a solid color. For DEMs each DEM grid cell is filled with the color corresponding to the elevation of that cell. For 2D Grids the color fill can be smoothed across cell boundaries (similar to the TINs method) or cell filled (similar to the DEM method).

A transparency value can be set for color filled contours so that an image or other data can be seen through the color filled contours.

Cubic Spline Contours

If the Cubic spline contours button is selected, the contours are computed in strings and drawn as cubic splines. In some cases, drawing the contours as splines can cause the contours to appear smoother.

Occasionally, loops appear in the splines or the splines cross neighboring contour splines. These problems can sometimes be fixed by adding tension to the splines. A tension factor greater than zero causes the cubic spline to be blended with or converge to a linear spline based on the same set of points. A tension factor of unity causes the cubic spline to coincide with the linear spline.

Legend

A legend displaying the range of colors and associated values can be turned on for the current set of contour options. The legend options include a title, font, size and position. By default the legend will be placed in the upper left of the graphics window, but can be positioned in the other three corners as well. This is important when displaying contours of more than one data set at a time.

Bold Contours

The Bold every... option can be used to display contours at selected intervals with a thicker line width.

Contour Labels

The Label every... option can be used to plot labels on contours at selected intervals. The contour label options are edited using the Contour Labels dialog.

Contour Specified Range

Regardless of which option is selected for the contour interval, a maximum and a minimum contour value can be specified and the contouring can be restricted to the specified range.

Contour Colors

The options in the lower right corner of the Contour Options dialog define what colors are used when the contours are displayed. The Color Options button is used to set the default contour color.

Related Topics

• Display Options
• Contour Labels
• Color Ramp