Full text: Proceedings of the Symposium on Global and Environmental Monitoring (Part 1)

formance. As a result, more accurate depth estimates 
can be obtained. In addition, the LIDAR bathymeter 
can be used for non-bathymetric purposes such as in 
the measurement of sea water turbidity. A quantitative 
measure of turbidity is the rate of attenuation of the 
laser beam in water and this rate is dependent on the 
degree of scattering and absorption of the laser light in 
water. 
4 CONCLUSIONS 
The mathematical characterization of the surface and 
bottom reflections in laser bathymetry has been exam 
ined. The bottom reflection can be represented by a 
Gaussian function and by adjusting parameter a, dif 
ferent possible reflection widths can be obtained. The 
surface reflection, on the other hand, can be represented 
by the EMG function and by adjusting S T , a variety of 
asymmetric reflection profiles can be obtained. Exten 
sive test results with real life data have shown that the 
application of the proposed characterization to LARSEN 
waveforms is indeed reasonable. 
A nonlinear least-squares optimization technique has 
been applied to facilitate the decomposition of each 
LARSEN waveform into the surface and bottom reflec 
tions. By using the Levenberg-Marquardt minimization 
method in conjunction with an initialization scheme, 
reliable depth estimates can be obtained for a diverse 
range of circumstances. 
ACKNOWLEDGEMENT 
The authors are grateful to the Natural Sciences and 
Engineering Research Council of Canada for supporting 
this research. 
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