OPTICAL PROCESSING OF AERIAL IMAGERY AND SEA ENERGY SPECTRA, 
AN APPLICATION OF REMOTE SENSING ONTO OCEANOGRAPHY. 
C. Romeu-Nedued* and R, Vilaseca** 
*Instituto de Investigaciones Pesqueras 
Paseo Nacionel s/n. 
Barcelona - 3, Spain 
** ab, Optica, Dpt? Fisica Fundamental 
Facultad de Ciencias 
Universidad Autónoma de Barcelona 
Bellaterra (Barcelona), Spain 
introduction 
The study of the diroctional properties of ocean uaves is 
recognized to be a helpful tool when studying wave generation 
mechanisms and is a basis for approaching cther problems in sev 
“eral applied areas of coastal dynamics or in wave Forecasting 
and ship motion. These properties may de deduced from the di- 
rectional wave spectrum which represents the wavs snergy density 
distribution with respect to direction and either spatial or ten 
poral frequency. Though this is a knoun characteristic, its 
applications have been scarce for e long time, mosily due to the 
difficulty of direct me:surement. 
Several methods for determining the directional properties 
oO? surface waves have been proposed: stereo photo raphy (1), 
pitch-and-roll buoys (2),(3), gauge arrays (4), (5), electromagn 
tic current-meters (6) and laser wave slope spectral method (7). 
Each of these methods has some advantages over the others, but 
the difficulties associated to each one of them act as a limit- 
ing factor in the spread cf their use. Numerical modelling has 
been also proposed to gain some knowledge of the directional 
spectrum in shallow waters, but these methods are either local 
or strongly dependent on the off-shore bathymetry and wind stress, 
so that further research in this sense is still needed. 
2 
BARBER (8),(9) suggested and epplied the optical method for 
the diffraction analysis of photographs. This method has been 
called later the hologrephic method and used first a sodium 
light as coherent illumination source. It was however the advent 
of the laser and the theoretical basis for the spectral analysis 
of surfaces waves derived by STILWELL (10) that made it become 
operational. The method is based on the fact that in the Fourier 
transform recording, density distribution represents slope dis- 
tribution, wave direction is the azimuth angle and wave number 
is proportional to the radius from the center. 
In the present study we apply sea photo-analysis to shallow