Contour maps of baselapping surfaces should have no contours in areas of baselap because the surface does not exist there. To baselap one grid onto another for map display, the elevation z values at each grid node are compared and the value of the baselapping grid is set to missing if lower or kept if higher than the other grid ([[:file:using-and-improving-surface-models-built-by-computer_fig9.png|Figure 9]]). | Contour maps of baselapping surfaces should have no contours in areas of baselap because the surface does not exist there. To baselap one grid onto another for map display, the elevation z values at each grid node are compared and the value of the baselapping grid is set to missing if lower or kept if higher than the other grid ([[:file:using-and-improving-surface-models-built-by-computer_fig9.png|Figure 9]]). |