International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 5. Hakodate 1998 
THE EXTRACTION OF 2-D SEA PARAMETER AT NEAR SHORE REGION FROM SEQUENCE 
ANALYSIS OF MARINE RADAR IMAGE AND ITS VERIFICATION S(k 
Shintaro GOTO, and Yoshibumi MIZUNO** Th 
i : ) e 
Associate Professor, Environmental Information Laboratory Wal 
Kanazawa Institute of Technology We 
7-1 Ohgigaoka Nonoichi Kanazawa Ishikawa 921, JAPAN ast 
E-mail: got env.kanazawa-it.ac.jp 
** Mitsui Zosen Systems Research Inc. « 
SCH 
Commission V, Working Group IC WG V/III 
Wh 
Wa 
KEYWORDS: Image sequence analysis, Optical flow model, Marine radar, Wave parameter wav 
sms 
wav 
ABSTRACT 
NEN Sue | | L= 
The Observation of 2-D wave parameter distribution is important for estimating the wave force to marine constructions, 
such as jetty. The in situ data routinely observed now are point data and the cost is expensive, so the number of whe 
observation point is a few. There is no routine method for monitoring 2-D wave parameter distribution.Marine radar can dep 
offer the image of 2-D wave field by monitoring the sea clutter from the sea surface. 
In this study we observed the wave parameter around the coast area near Komatsu city besides Sea of Japan by marine 
radar from Jan.8 to Jan.11, 1996 when the highest significant wave in winter of 1996's was observed. From Image of 
marine radar we obtained the wave direction and wave speed by optical flow estimation. Wave direction and wave speed 
were calibrated by the result of FFT and in situ data by Ministry of Construction Japan. The Accuracy of wave direction 
fits to the in situ data. But the accuracy of wave frequency is lower than wave direction. To examine this correlation, the 
nonlinearity caused by wave breaking was investigated with the simulation study using in situ measurements. 
  
1. INTRODUCTION 
The Observation of 2-D wave parameter distribution is 
important for the estimation of the wave force to marine 
constructions, such as jetty. The in situ data routinely 
observed now are point data and the cost is expensive, so 
the number of observation point is a few. There is no 
routine method for monitoring 2-D wave parameter 
distribution. 
Marine radar can offer the image of 2-D wave field by 
monitoring the sea clutter from the sea surface. 
F.Ziemer,and W.Rosenthal!) was developed the transfer 
function for marine radar for imaging ocean waves. After 
applying the transfer function to the image spectra, 
significant wave heights were estimated and compared 
with results from other sensors during LEWEX2). Results 
of their study are very promising. And M.D.Henschel et 
al3) developed the prototype marine radar ocean wave 
imaging system, MACRADAR, for validation of the ERS-1 
SAR wave mode operation by using F. Ziemer et al 's 
method. But their application was carried out only on the 
offshore region. 
In this study we observed the wave parameter around the 
coast area near Komatsu city besides Sea of Japan by 
marine radar from Jan.8 to Jan.11, 1996 when the highest 
significant wave in winter of 1996's was observed. From 
Image of marine radar we obtained the wave direction 
and wave speed by optical flow estimation. Wave 
direction and wave speed were calibrated by the result of 
FFT and in situ data by Ministry of Construction Japan. 
698 
The Accuracy of wave direction fits to the in situ data. But 
the accuracy of wave frequency is lower than wave 
direction. 
2. METHODOLOGY OF WAVE PARAMETER 
DETECTION 
2.1 Wavelength and Wave Direction by FFT 
Fig.1 shows the flow diagram of analysis procedure. As 
the received power from the sea surface become more 
and more weakly as the radar is far from the radar site. 
The correction function are applied to correct the 
difference of these power due to the distance from the 
radar to the sea surface. And the received power from the 
radar is PPI image shown as Fig.2 on polar coordinate 
system, so the image is transformed to x-y coordinate 
system for FFT analysis. The Fourier transformation 
F(kx,ky) is defined by 
oc 
F(kxky)=1/(27)2 + [7 (xy) * 
Ex 
exp(-i(kxx+kyy))dxdy |. su. 1) 
2(Xy) is the radar image defined on x-y coordinate 
System. And Wave number spectrum is defined by