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<br />Tuesday, May 19 1:30 - 3:00 PM Track 6 - Mapping Techniques II - Moderator: Larry Olinger <br /> <br />VERTICAL MAPPING TECHNOLOGIES: LlDAR AND IFSAR VS. PHOTOGRAMMETRY <br />Stephen DeLoach, PE. LS. <br /> <br />USGS Levell Digital Elevation Models (DEMs). derived from automated photogrammetric compilation, typically have root mean square <br />(rms) elevation errors of? meters. The more-accurate Level 2 OEMs, derived from contour lines on topographic maps, are generally <br />accurate to one-half the contour interval. Thus, OEMs derived from topographic maps with a 1 a-foot contour interval would have elevation <br />errors of "S-feet More accurate OEMs are possible, of course, from stereo photogrammetry, but lhey require a higher nwnber of aerial <br />photographs, flown at lower altitudes and much higher costs, <br /> <br />Airborne GPS positioning of mapping aircraft at the instant aerial photos are taken, and inertial sensors for direct determination of roll, pitch, <br />and yaw, simplity the analytical aerotriangulation process traditionally used by photogrammetrists, In i.ct, airborne GPS and inertial sensors <br />may totally eliminate the requirement for aerotriangulation and survey ground control; and digital cam<:ras may eliminate the need for metric <br />Jilin cmneras, But airborne GPS :md inertial sensors also simplify the use of Light Distancing and Ranging (LIDAR) laser technology, and <br />Interferometric Synthetic Aperture Radar (IFSAR) technology, for direct and more accurate production of high density, high accuracy <br />DEMs, <br /> <br />This presentation will explain these technologies and compare their advantages and disadvantages for toe generation of high accuracy OEMs <br />for improved hydrologic and hydraulic (H&H) modeling and analyses, <br /> <br />RESULTS OF THE "NATIONAL HEIGHT MODERNIZATION STUDY" <br />David F. Maune, PhD., c.p, <br /> <br />Dewberry & Davis will report on this nationwide study, being prepared for submission to Congress on June I, 1998, which could <br />signiJicantly help the Natiooal Flood Insurance Program :md nwnerous other users of elevation data. The National Geodetic Survey (NGS) <br />study report will request Federal funding for high accuracy Digital Elevation Models (DEMs) prodnced by LIDAR and IFSAR; a <br />Nationwide Differential GPS system (NDGPS); and nationwide elevation surveys needed for proactive floodplain management <br /> <br />THE ROLE OF AUTOMATED H&H IN FEMA'S NEW MAP PRODUCTS <br />Tim McCormick and Sue Hoegberg <br /> <br />The new floodplain mapping products that will be developed under FEMA's Map Modernization initiative offer floodplain managers a <br />framework for integrating engineering data more closely with the floodplain maps. A key component of this framework is the ability to lie <br />hydrologic and hydraulic models to the maps, This linkage will allow communities, revision requesters, and FEMA to more efficiently <br />evaluate changes to the Flood Insurance Rate Maps. This session will provide an overview of how toe DFIRM 2, I product will enable the <br />integration of key H&H information with the maps. <br />