STEREOPHOTOGRAMMETRIC WAVE MEASUREMENT 



rORtWORD 



The following article was prepared for the Beach Erosion Board 

 as Technical Report NOo 5s Photo gramme trie Division, Army Map Service, 

 by Mr. Lewis A. Dickerson, The test was suggested in part by the 

 work of Schumacher on the German "Meteor" Expedition, who, it is 

 believed, was the first to demonstrate the possibilities of stereo- 

 photography in wave measuremanto The work reported herein was per- 

 formed in connection with a study of wave gauges which appeared as 

 Technical Wfemorandum No.. 6, Beach Erosion Board, 



Purpo^se^ 



This report covers the investigations and experiments conducted 

 by this organization to determine the feasibility of measuring the 

 heights of ocean T.-aves by photo gramme trie means. This work was under- 

 taken upon the request of the Beach Erosion Board, Corps of Engineers, 



Factual Data 



Location of Tsst Area - The test area, which was set by the 

 Beach Erosion Board, was that portion of the Atlantic Ocean off the 

 end of the Steel Pier at Atlantic City, New Jersey, The end of the 

 pier was used as the base from which to perform the photographic work. 

 The photo gramme trie instrument work was performed at the ArnQr Map 

 Service . 



First Test 



The first test photography was performed by the Beach Erosion 

 Board. Photography was accomplished during the period A-6 August 194-7 « 

 Two Fairshild F-56 aerial caireras were used for the photography. These 

 cameras had a focal length of 8^ inches (nominal) and exposed a film 

 negative 7 x 7 inclies. These cameras were not of a precision photo- 

 gramme trie type . 



One camera was mounted rigidly on each corner of the end of 

 the pavilion on the Steel Pier as shown in Figure 1. The distance 

 betifreen the cameras was 99 feet. The cameras v/ere pointed seaward 

 with their optical axes approximately horizontal, parallel, and normal 

 to the base line between thera„ The elevation of the cameras was not 

 determined. The shutters of the two cameras were connected electrically 

 so as to be tripped simultaneously. The exposures were made on Kodak 

 Aerographic film using a shutter speed of 1/75 second and an aperture of 

 F 4.5 with a j'-ellow filter. Several exposures were made and cheeked 



