How Do I Define a Custom Selection of Levels for a Contour Plot or Surface Plot?
The primary controls for defining contour intervals for 3D surface or contour plots are accessed on the Surface Specifications dialog obtained by clicking the Surface specs button on the Plot: Fitting tab of the All Options plot customization dialog. (Display the All Options dialog by double-clicking on the outer background area of the graph.) Number of contours/levels. The number of color levels placed on the graph is determined by default by the number of minor tickmarks spanned by the surface on the Z axis of the plot. This default option is in the Get shading levels from box near the top of the Surface Specifications dialog (available by clicking the Surface specs button on the Plot: Fitting tab). Note that other options for determining the number of contour levels to place on the graph include major tickmarks, custom tickmarks, and combinations of custom with major or minor tickmark options. Specifying intervals. To control the numeric values that divide contours, use the Custom U
