METHODOLOGY OF WAVE MONITORING AROUND COASTAL STRUCTURES WITH UAV

Abstract

 Recently, UAV has been recognized as a powerful tool to observe beach morphology and also near-shore wave characteristics. Although the methodology of wave monitoring with UAV has been discussed in recent years, it still has some technical challenges. In this research, (1) we are developing an automatic ground control points tracking method for geometric correction of images, (2) considering the relationship between a position of UAV and appearance of waves in aerial images through a numerical experiment, (3) developing a new method to extract wave direction from the wave field where incident waves and reflected waves from the coastal structure interfere. For these, we have derived the following conclusion in this research. We succeeded in constructing an automatic tracking algorithm of ground control points with sufficient precision and reduced analysis cost. It was found that the position of UAV greatly affects visibility of waves. Through the numerical experiment based on Fresnel’s law, the characteristic distribution of spectrum amplitude of image intensity is obtained in the wave field where the reflected wave and the incident wave interfere with each other, and the wave direction can be extracted from this distribution.