STATISTICA offers a selection of facilities to custom define the levels for contour and surface plots (see the Surface Specifications dialog topic, and the description of options in the Graph: Surface options pane of the Graph Options dialog). In general, the shading levels of surface levels and contours can be related to the major or minor tickmarks of the vertical (z) axis scaling, while the vertical (z) axis scaling itself can be fully controlled by the respective Axis options of the 3D Surface plot Graph Options dialog.