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United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for Managing Water and Sediment Movement in Agricultural Watersheds

Location: Watershed Physical Processes Research Unit

Title: Water surface capturing by image processing

Authors
item Ozerne, Yavuz -
item WREN, DANIEL

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 13, 2012
Publication Date: August 13, 2012
Citation: Ozeren, Y., and Wren, D. G. Water surface capturing by image processing. Hydraulic Measurements and Experimental Methods Conference, Snowbird, Utah. 6 pp. 2012. CD-ROM.

Interpretive Summary: Measuring the water surface interface during laboratory experiments is important in wave-based research. Image processing can provide a continuous, non-intrusive record of the water surface profile whose accuracy is not dependent on water depth. More traditional methods, such as capacitive wave-height sensors, only provide water surface elevations at a limited number of discrete locations and must be in contact with the water. A consumer-grade video camera can provide an adequate number of measurements for many applications, helping to reduce the cost of laboratory equipment. Here, an image analysis procedure was developed for wave height measurement in laboratory tank using a consumer-grade digital video camera. The results were in very good agreement with the recoded wave height measured using another reliable method.

Technical Abstract: An alternative means of measuring the water surface interface during laboratory experiments is processing a series of sequentially captured images. Image processing can provide a continuous, non-intrusive record of the water surface profile whose accuracy is not dependent on water depth. More traditional methods, such as capacitive wave-height sensors, only provide water surface elevations at a limited number of discrete locations and must be in contact with the water. When the variation of the water surface along a distance parallel to the flow direction is important, or if the flow contains obstacles that interfere with data collection, such as vegetation, image processing can be a useful tool. A consumer-grade video camera (˜30 Hz frame rate) can provide high temporal and spatial resolution since each frame captures a section of the water-surface profile at many locations simultaneously. Here, an image analysis procedure was developed and utilized to measure regular waves propagating over flat and vegetated surfaces using a consumer-grade digital video camera. The analysis included distortion and camera alignment corrections. An average frame analysis was used in addition to the frame-by-frame analysis to estimate the wave height. The results were in very good agreement with the recoded wave height at four capacitive wave gauges. The new method enabled resolution of the spatial distribution of wave height evolution and the standing wave pattern along the vegetation field.

Last Modified: 9/10/2014
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