Abstract: Methods, systems, and computer readable media use closed contours of a modeled surface for various purposes such as displaying a contour map of the modeled surface or computing volumetrics. For the closed contours, a colorfilled contour map may be displayed where each contour level is represented as a shape that has an opaque fill color by calculating the area of each shape and displaying the shapes in decreasing order of area. Where both elevations and depressions are present, such that elevations have a positive area and depressions have a negative area, the shapes are displayed in decreasing order of the absolute value of area. Where null values in the modeled surface are present such that unclosed contours result, values are substituted into the null values to close the contours. These closed contours may then be used for various purposes, such as calculating volumetrics of the modeled surface or generating the colorfilled contour map display according to the area of the closed contours.