| The surface topology of the three-dimensional density map is defined by the outermost contour line. |
| It is a contour line, dividing areas that are more than half selected from areas that are less than half selected. |
| As soon as the contour line for the verifying analysis is available, it is added to the figure. |
| The software defines the contour line lying between the points as the reference contour and identifies the reference contour in blue. |
| The figures have been depicted within a frame delineated by a deep contour line. |
| The line would follow a particular elevation — ten feet above sea level — much like a contour line on a map. |
