Hydrology for all: Image-based water level monitoring

How does it work? Finds water line in an image Calculates the water stage Stores both the value and the image Provides live services in the form of stage, images, videos, alerts.

What does it take? A good Webcam A good camera stand A good flat background An ftp server A machine vision software to calibrate the images Remote clients (smartphones, computers, etc.) to visualize, download data

A good Webcam Objective: install virtually anywhere in the world Live images require 3G coverage Picture of unsecured prototype: new packaging in testing

A good 3G webcam

A good stable stand for stable images

Picture of older prototype. New and improved prototype in testing

A good flat background

A machine vision software to calibrate the images

Remote clients to visualize, download data

Preliminary results Results borrowed from – Gilmore, T.G.,F. Birgand and K. Chapman. Source and magnitude of error in an inexpensive image- based water level measurement system. Submitted November, 10, 2011 to Journal of Hydrology

Can we detect water level?

Can we measure water level? Detection and linkage to real world measurement

The System: Edge Detection

The System: Calibration

x = 0 cm, y = 75 cm x = 0 cm, y = 45 cm

Uncertainty: Three Experiments 1.Image Resolution 2.Lighting effects* 3.Perspective 4.Lens distortion 5.Water meniscus Benchmark II Benchmark I Water Level

Uncertainty: Camera effects Lighting* Meniscus Effects

4m, 12 mm5 m6 m7 m cm per pixel Mean Bias, SD, RMSE (cm) Standard error for several image resolutions in the lab

Water Level: Posture Angle 19 deg 10 deg For camera at 6 meters

Water Level: 6m, 16mm lens posture angle from horizontal (degrees) 1910

Preliminary recommendations and performance 1.Lens distortion must be minimized 2.Posture angle may interact with meniscus 3.With reasonable precautions, accuracy of +/- 3 mm (0.01 ft) is achievable in the lab

Products Data Pictures Videos Alert Remote actions in the field (work in progress)

Miscellaneous pictures

Picture of Prototype of camera mount – a secured version is in testing

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