FIGURE 1.1 The major map components of a Digital Flood Insurance Rate Map (DFIRM). Top left: the base map imagery, an orthophoto, for a floodplain map upon which familiar map planimetric elements (roads, rivers, buildings, vegetation) can be identified; top center: the digital elevation data overlaid on the orthophoto give each element in the orthoimage an accurate vertical position; top right: flood hazard data, collected and modeled by surveyors and engineers in the field, are then digitally overlaid onto the ortho- and elevation map to produce the DFIRM. This report addresses the technologies used to generate the orthoimage (base) and digital elevation data of the DFIRM. Together, we describe the imagery base map and the elevation data as the “framework data” of the DFIRM in this report. SOURCE: Adapted from Maune, 2007. Reprinted with permission from the American Society for Photogrammetry and Remote Sensing.