GPS for Dummies.pdf - Engineering Surveyor

Chapter 16: Going Three Dimensional with 3DEM271Working with overlay mapsAfter you create an overlay map, you can print, save, and create 3-D scenesjust like with the map made from the DEM data in the preceding section.In Figure 16-7, you can see a 3-D scene of inside the Mount St. Helens craterwith overlaid DRG data. Most of the menu and dialog box commands that Idescribe in earlier sections of this chapter work the same.Figure 16-7:A section ofan overlaymap displayedasa detailed3-D scene.One command that’s unique to working with overlay maps displays the topographicmap without any relief shading (just like the paper version of the mapwould appear). To view the overlay map with no relief shading1. Use the View tool to define the area you want to view. (Move and resizethe view square to choose the area.)2. Choose Map Overlay View from the Operation menu.3DEM displays the selected area as a topographic map without shading.To navigate around the map, use the window scroll bars.3. To return to the shaded relief overlay map, choose Overhead Viewfrom the Operation menu.