Part 3 

 HISTORY 



For some years now tke desirability of obtainiag tke two-dimeasional 

 sea spectrum has beeji explained in the literature (Pierson [1952] and St. 

 Denis and Pier son [1953]) When most of the methods considered were 

 found lackingi the technique of stereo-photography of the sea surface seemed 

 most amenable to possible methods of analysis (Marks [1954a]). 



Representatives of the Woods Hole Oceanographic Institution initiated 

 the first steps necessary to convert the idea of aerial stereo-photography of 

 ocean waves into fact. At a meeting in Washington, the requirements for 

 such an undertaking were established, and, equally important, the Photo- 

 grammetry Division of the U. S. Navy Hydrographic Office expressed an 

 interest in the job of reducing the photos to numerical data form. As a re- 

 sult of this discussion, the first formal plan for obtaining the stereo-pairs 

 was set down (Von Arx [1952]). The basic requirements were as follows: 



1. Two aircraft to fly parallel, 600 feet apart, at 1000 feet; 



2. Each to have a CA=8 metrogon camera aimed vertically down and 



CMae long focus 35 mm catnera aimed at companion aircraft to 

 determine the length of the stereo-base line; 



3. Cameras to be triggered within 10 millisecoads of each other by 



an FM pulsei 



4. Smoke bomb pattern to provide ground control; 



5. Upwind flight of planes with flaps down to reduce plane speed and 



18 



