Camera
This study also tested the effectiveness of consumer-grade time lapse cameras as a complementary approach for measuring wind-waves in shallow intertidal mudflat environments. Image processing techniques have become increasingly common in coastal environments in recent decades. Approaches for utilizing cameras to gather data are well-established for tasks such as stream gauging (citation), tracking tidal levels (citations), measuring ocean wave conditions (citations), and mapping coastal geomorphic processes such as offshore bar formation (citations). However, equipment costs and the upfront training costs needed to learn image processing techniques typically preclude the use of cameras when standard methods are available (e.g. pressure sensors, buoys). Recently, the widespread adoption of time-lapse cameras in commercial applications has driven down costs, while the resolution of consumer-grade cameras has also risen substantially. Both trends mean that image processing will become more viable if the techniques become widely available.
There are several potential benefits for using cameras to measure wave heights in the shallow intertidal zone:
(1) Long-term site plans for shoreline erosion, for constructed restorations, or for living shorelines implementations already commonly use time lapse photography for monitoring. If wave data collection from images is possible, this existing monitoring could be optimized to also collect quantitative wave data.
(2) Camera-based wave measurements can potentially be made at multiple spatial locations within a camera field of vision. This could allow for studies of wave height reduction across a transect of marsh or mudflat without the need for multiple devices.
(3) As the cost of time lapse cameras continues to fall, and resolution continues to improve, image processing could become a relatively inexpensive complementary form of wave data collection.
This study also looks at some of the limitations of the approach. We use concurrent data collection from sonic sensors and camera techniques to understand what the magnitude of the uncertainties and the conditions (ambient lighting, site constraints, camera resolution and field of view) that increase or decrease uncertainty.
Wave Measurements in San Francisco Bay, wave measurement on Tidal FLats and Marsh Land