6309RS0001 

 KELLER, MORTON, "Tidal Current Surveys by Photogrammetric Methods," Technical 

 Bulletin No. 22, U.S. Coast and Geodetic Survey, Washington, D. C, 1963. 



Keywords: Aerial Photographs, Photogrammetry, Water Currents, Charleston Harbor, 

 South Carolina 



Bulletin describes procedure employed in the USC&GS to measure tidal currents by 

 photogrammetry. The basic principles of the photogrammetric measurement of current 

 velocity and direction are discussed. Technique is based on measurement of the movement 

 of floating surface targets between the exposure of overlapping photos. Design and 

 placement of the surface targets are covered. Report describes a photo survey of tidal 

 currents in Charleston Harbor, South Carolina. Current surveys at Ocracoke Inlet, North 

 Carolina, and Tampa Bay, Florida, are discussed. A comparison of current velocities with 

 data from current velocities with data from current meters in Charleston Harbor indicated 

 satisfactory results by photogrammetry. 



6311RS0001 

 SMITH, JOHN T., JR., "Color— A New Dimension in Photogrammetry," Photogrammetric 

 Engineering, Vol. 29, No. 6, Nov. 1963, pp. 999-1013. 



Keywords: Color Aerial Photographs, Coastal Mapping 



Article discusses use of color photos in nautical chart preparation and maintenance in the 

 USC&GS and the advantages of color over black and white photos. Color photos show 

 clearer bottom detail. Several excellent color photos show Key West and Everglades 

 National Park, Florida; Hyannis Port, Massachusetts; Seattle, Washington; and a large eddy 

 north of St. John's Island in the Caribbean. Procedures for exposing and processing color 

 photos are given. The problem of sunspots on color photos of water and techniques for 

 reducing the detrimental effects of the sunspots is discussed. 



6311RS0002 

 TEWINKEL, G. C, "Water Depths from Aerial Photographs," Photogrammetric Engineer- 

 ing, Vol. 29, No. 6, Nov. 1963, pp. 1034-1042. 



Keywords: Aerial Photographs, Water Depths 



Report discusses factors that cause errors in water depths determined from photogram- 

 metry. Under consideration are depths of clear shallow water. The primary factor is the light 

 refraction at the air-water interface. An equation is derived for a factor that, when 

 multiplied by water depths determined in a stereoplotter, corrects for the refraction. 

 Correction factor varies with location in the stereo model and also with water depth. 

 Average value of the factor is between 1.4 and 1.5 for a water depth of 60 feet. Water 

 depths from a plotter and corrected for refraction are not affected by camera tilt; horizontal 

 locations of bottom details are not affected by refraction when using a plotter. Surface 

 waves cause an error averaging about 8 percent in depth determinations and produce a 

 y-parallax that can cause an erroneous orientation of the model if underwater points are 

 used. 



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