If the data are displayed as a shaded relief image, the appearance of the artifacts will vary depending on the direction of illumination, vertical exaggeration applied, and the scale of the display. Generally, none of the artifacts will be visible on a course-scale portrayal of the global data set. Some production artifacts are also present in the areas derived from the vector sources. Small artificial mounds and depressions may be present in localized areas, particularly where steep topography is adjacent to relatively level areas, and the hypsography data are sparse. Here the transition between contour line elevations does not slope constantly across the area but instead is covered by a flat area with sharper changes in slope at the locations of the contour lines.
Histograms show sharp peaks at elevations that are multiples of the source s contour interval.
This effect is common in DEMs produced by gridding of contour data, in which the interpolation process favors elevations at or near the contour values, thus leading to a greater frequency of those elevations. Every effort to reduce these effects has been made by careful selection of parameters for the interpolation process.