GPS for Dummies.pdf - Engineering Surveyor

272Part III: Digital Mapping on Your ComputerReviewing Other 3DEM Features3DEM has a number of other features worth mentioning: Multiple DEM file support: Instead of loading only a single DEM file at atime, 3DEM can merge DEMs to create 3-D models of large areas. GPS support: Waypoints, routes, and tracks can be downloaded from aGPS receiver and displayed on maps created by 3DEM. Aerial photo overlays: Aerial photographs can be overlaid on DEM data,just like DRG files, to create three-dimensional photos. (You need to georeferencethe photos first, which consists of identifying the coordinatesof several known points on the photo.) Flyby animation: 3DEM can create animation movies of flying over athree-dimensional scene. Additional data sources: 3DEM isn’t limited to using only DEM and DRGdata. 3DEM can create maps based on elevation data gathered by satellites,the Space Shuttle, and even Mars exploration probes.After you master the basics of working with 3DEM, spend some time experimentingwith other program features. 3DEM has an extensive online Helpsystem that you can use to find out more about all aspects of the program.If creating 3-D maps interests you, be sure to check out the Virtual TerrainProject at http://vterrain.org. This Web site is a clearinghouse for 3-Dterrain modeling information. You’ll find a number of links to resources andtools for creating three-dimensional maps of land forms and both natural andman-made features.Other 3-D Mapping Software3DEM isn’t the only kid on the block when it comes to creating 3-D maps.Several other free or inexpensive Windows programs are available that youcan use for three-dimensional terrain modeling.Global MapperGlobal Mapper is an easy-to-use, reasonably priced, and powerful mappingprogram that has some of the same features as 3DEM for processing DEM andDRG data. Global Mapper also has some options typically only found in expensiveGeographic Information System (GIS) programs, including