Measuring tree sway frequency with videos for ecohydrologic applications: Assessing the efficacy of Eulerian processing algorithms

However, existing instruments used to measure tree sway lack spatial scalability. We investigate whether the virtual vision sensor and multilevel binary thresholding video processing algorithms can be used to accurately extract tree sway frequency at multiple points in a video camera field of view to enable scalable measurements of ecohydrologic processes.

Comparing sway frequencies extracted from video and accelerometer data at three sites, we show that for 30–60 second videos, the video processing algorithms can reproduce 30-minute accelerometer sway frequencies with ±0.02 Hz accuracy. The results suggest that video processing algorithms may be suitable for applications where changes in sway frequency are on the order of tenths of hertz or larger, for example the measurement of snow intercepted in tree canopies.