Embed Size (px)
DESCRIPTION
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 - PowerPoint PPT Presentation
Citation preview
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
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: Edge Detection
The System: Edge Detection
The System: Edge Detection
The System: Calibration
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 m 6 m 7 m
cm per pixel
Mea
n Bi
as, S
D, R
MSE
(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)
19 10
Preliminary recommendations and performance
1. Lens distortion must be minimized2. 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
