Conclusions
A phctzgraph of the sea surface ia a valucble representa-
tion of the surface under fairly common conditions. The holo-
graphic method can be easily applied to obtain the sea power
spectrum being the main limitations imposed by the flight alti-
tude and the field cf vieu of the camera for the maximum obser-
vable wavelength and by the resolution for the minimum. The
method is best applicable under clear sky conditions znd smooth
sea state, for otherwise datz processing may bec me a large and
tedious work, not always uorthuhile if the imagery selection has
not been careful. The limitations imposed by the optical pro-
cessor are shown to be partially eliminated following our con-
figuration uhich is easy to align, very simple,and permits the
experimenter to control the scale of the Fourier transform. Fur
thermore, it is uell suited for small laboratories that do not
dispose of 2 relevant number of facilities. An cther yay to
improve the patterns appearing on: the Fourier transform plane
consists in reducing the scale of the photography. This, as
stated before, is felt to be not desirable but carefully done
it ameliorates the system if the originally resulting transfor-
mate is too concentrated. It is sometimes noticed, however,that
the Fraunhofer pattern for large wave numbers is not symmetrical
due to aberrations in the lens or to small avoidable errors in
‘the adjustment of the optical processor. The use of imagery that
has not been taken considering the possibility of obtaining direc
tional prcperties of sea surface waves is a limitation but not a
hindrance in their use. Moreover one picture may serve to gain
a valuable assessment of sea state conditions at a particular
time, becoming a helpful tool when evaluating other remotely
sensed data. The use of the photochemical equidensity method for
analyzing the Fourier transformates is shoun to be convenient for
the interpretation and evaluation of the results. When assigning
colors to each tonality of grey, not more than eight colors
should.be used. This work is a preliminary rapport on.the anal-
ysis of the collected imagery of the oceanographic missions
NAUCA 77 and DELTA 77 and will be continued including an analysis
of the spectral differences of the directional wave spectrum and
the applicability of the coherent equidensitometry method.
Acknowledgements
The authors wish to thank Prof. Dr. A. Ballester and Prof.
Vallmit jana for their many fruitful discussions and encourage-
ment; J. Biosca for the photographic work and assessment; R. Sian
co for providing the Vivitar lens; INTA-CONIE for providing the
transparencies and make this work possible.
Resumen
El tratamiento óptico de imágenes aéreas mediante luz cohe-
rente permite obtener el espectro oidimensional de Fourier de la
densidad óptica de la transparencia usada. El análisis de la
