Elevation Data for Floodplain Mapping (2007) / Chapter Skim
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Appendix C Glossary
Appendix C Glossary
Pages 135-148
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From page 135... ...
The general measure of relative accuracy is an evaluation of the random errors (systematic errors and blunders removed) in Portions of this glossary reprinted from Appendix B of Maune, 2007, with permission from the American Society for 1 Photogrammetry and Remote Sensing.
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From page 136... ...
and IFSAR (interferometric synthetic aperture radar) , the attitude is normally defined as the roll, pitch, and heading of the instrument at the instant an active pulse is emitted from the sensor.
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-- A relatively permanent, natural or artificial, material object bearing a marked point whose elevation above or below an adopted vertical datum is known. • Tidal Bench Mark -- A bench mark whose elevation has been determined with respect to mean sea level at a nearby tide gauge.
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See Table 2.3 for a listing of 26 different vertical datums included in the National Geodetic Survey (NGS) Vertical Datum Transformation Tool (Vdatum)
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system contain • ing a coordinate system and points that have been consistently determined by observations, corrections, and computations. The North American Vertical Datum of 1988 (NAVD88)
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Flood Insurance Rate Map (FIRM) -- An official map of a community on which the Federal Emergency Management Agency (FEMA)
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Ground Sample Distance (GSD) -- The size of a pixel projected to the ground surface, as reported in linear units per pixel.
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Interferometric Synthetic Aperture Radar (IFSAR) -- An airborne or spaceborne interferometer radar system, flown aboard rotary or fixed-wing aircraft or space-based platforms, used to acquire three-dimensional coordinates of terrain and terrain features that are both man-made and naturally occurring.
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From page 143... ...
Mass Points -- Irregularly spaced points, each with x,y coordinates and z-value, typically (but not always) used to form a triangulated irregular network (TIN)
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Examples are geographic position (latitude, longitude, and altitude) , universal transverse mercator (UTM)
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Radar, Synthetic Aperture -- A radar containing a moving or scanning antenna; the signals received are combined to produce a signal equivalent to that which would have been received by a larger, stationary antenna. Range, IFSAR -- The distance in a direction perpendicular to the flight path (cross-path direction)
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See American Society of Civil Engineers (ASCE) , American Congress on Surveying and Mapping (ACSM)
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From page 147... ...
-- also called soft copy workstations -- that have significant advantages compared to analytical stereoplotters. These advantages include automatic digital image correlation, efficient production of DEMs and digital orthophotos, and superposition of all types of geospatial data over digital imagery.
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From page 148... ...
Void -- Portions of a digital elevation dataset in which no elevation data are available. In USGS DEMs, each elevation post located within a void area is assigned a discrete false value representing the void.
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