Stereophotography of ocean waves

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- 1

-1. Introduction

The Delft University of Technology and the Ministry of Public Works in the Netherlands jointly developed a system to measure the instantaneous three-dimensional sea surface by means of

stereophotography from helicopters. The objective of this report is to describe this system.

The system was developed as one of the elements in a study of the directional characteristics of ocean waves. This study was primarly aimed at estimating the two-dimensional spectrum of waves which gives the distribution of wave energy over wavelengths and directions. The system and procedures which are described in this report are based on the requirements to measure this spectrum.

The arrangements of the chapters is as follows. In chapter 2 some basic elements of the system are described. A description of the operational system and procedures is given in chapters 3 and 4 respectively. The procedures for the analysis of the photographs are described in chapter 5.

Information on the system has also been published elsewhere. In Holthuijsen et al. (1974) an integrated, but less detailed, review is presented and in v.d. Vliet (1972, 1974) a detailed description of the electronic components is given. Some preliminary results with emphasis on wind wave properties have been reported in Holthuijsen (1978).

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