when data are available to determine the height of the cameras above 

 tide level at the time of photography and the relationship between 

 troughs, crests, and tide level. This would not be likely in any 

 application of the nethod. 



Although the method tested, and as described above, did not permit 

 the determination of Virave heights, it is still possible that this can 

 be done photograrametrically. Two alternatives present themselves. 

 The first is an arrangement similar to the one described in the above 

 tests but arranged so that the camera axes are pointed in a direction 

 of travel of the waveso This should permit ireasurements in the bottom 

 of the trou^s and on the crests of tte waves. It should be noted, 

 however, that in this system the mounting of the cameras must be such 

 that they retain a fixed and known relationship to each other , For 

 example, they could not be mounted on a floating vessel unless attached 

 to a rigid framework which in turn is not rigidly attached to the 

 vessel o The second alternative is the taking of vertical photographs 

 much in the same manner as for topographic mapping. Due to the low 

 altitudes involved, a lifter than air craft or a helicopter would be 

 necessary for this purpose in order to secure the slow air speeds 

 necessary. Two cameras would have to be mounted so as to expose 

 simultaneous and overlapping photographs. The mountings of the cameras 

 would not require extreme rigidity although it would be necessary to 

 know the distance between cameras to an accuracy of about 0,5 inch. 

 The flying teight could be between 100 and 50O feet, depending upon 

 what distance the cameras are mounted apart. 



Conclusions 



From the tests described above and the brief discussion, it is 

 concluded that: 



With tte methods used in the test it is not possible to 

 determine the heights of ocean waves 



Photographs of wave formations can be made so that measure- 

 ments of sufficient precision can be made by photo gramme trie means. 



To be of value for wave height determination, the photo- 

 graphs must be exposed so as to record both the bottoms of the troughs 

 as well as the crests of the waves. 



That "contouring" of wave formations is extremely difficult 

 and of little value . 



A3 



