Click the Line button in the 3D wireframe dialog Color Zones or Z Levels page, or click the Line button in the grid node editor Contour Levels dialog to open the Line Spectrum dialog and create gradational line color.
Specify the line properties in the Line Spectrum dialog.
Minimum and Maximum Line Properties
Click the Minimum Line Properties and Maximum Line Properties buttons to specify the line style, color, and width for the minimum and maximum levels. When you click the Minimum Line Properties or Maximum Line Properties button, the Line Properties dialog is displayed. The minimum line property is assigned to the lowest contour level and the maximum line property is assigned to the highest contour level. Surfer automatically assigns gradational line colors or widths between the minimum and maximum levels.
If you choose different line styles for the minimum and maximum contours, there is no gradational change in line styles. The lower half of the contour lines use the style assigned for the minimum and the upper half of the contour lines use the style assigned for the maximum.
If you do not want to display contour lines for a plot you can assign an invisible line style for both the minimum and maximum lines from the Line Spectrum dialog.