David S. Simonett 1968 <p>This paper reviews the literature, especially of the last two years, dealing with remote sensor evaluation of surface and shallow sub-surface characteristics, employing remote sensors in the infrared (1.5p. - 14p.) and radar (0.5 cm - 100 cm) regions. Imaging and non-imaging sensors are examined to assess their current status and possible value in 1) assisting in the mapping of natural plant communities , 2) deriving hydrologic parameters, 3) discriminating among broad land use, crop type, and to a lesser degree, crop state,4) delineating soil and geomorphic units, and 5) estimating soil moisture. Possible applications of these remote sensors in reconnaissance-scale evaluation of natural resources are considered. The paper leans heavily on unpublished and limited-circulation studies sponsored by the National Aeronautics and Space Administration, U.S.A.</p> application/pdf 10.3133/ofr68250 en U.S. Geological Survey Land evaluation studies with remote sensors in the infrared and radar regions reports