Determination of wave slopes from photographs of the ocean surface: a new approach.

A general nonlinear technique is described for determining wave slopes from photographs of an area of the ocean surface that is illuminated by diffuse skylight. This technique is evaluated using uniform, overcast, and bright sky radiance distribution models, and results from its use are compared with the approximate results obtained by previous authors. Under certain clearly defined practical experimental conditions, it is theoretically possible to determine the total wave slope magnitude at the ocean surface.

Twin-prism stereo-separator.

We describe a twin-prism stereoseparator for the Zeiss fundus camera which gives high-quality stereophotographs of the optic disc and simultaneously records both images on the same frame of film. The stereobase of photographs taken with this system ranges from 2.0 to 4.