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agu_abstract.txt
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agu_abstract.txt
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Observation of volcanoes through webcams: Tools and techniques
This work explores techniques for deriving quantitative data from webcam
observations. It illustrates the role that webcams can play in volcano
monitoring, and shows our recently developed tools for the collation and
dissemination of this data.
Over the past 5 years, digital cameras have been installed at a number of
volcanoes to allow the general public to see volcanic activity from the
comfort of their own homes. In the last 3 years these webcam images have
become part of the twice-daily volcano monitoring report by the remote
sensing team of the Alaska Volcano Observatory (AVO).
To allow comprehensive and systematic analysis, a database has been created
containing all AVO webcam images as well as images from St. Helens and
three KVERT webcams for Bezymianny, Klyucheskoy and Shiveluch. In total,
some 1.6 million images are currently held. The number increases daily as
new images are obtained and processed.
The database holds additional information about each image such as both
image-wide and localized-region statistics. Our tools have been developed
to answer specific questions utilizing this data.
Of the current 1.6 million images in the database, a very small percentage
is considered interesting for volcano monitoring; the remainder can be
ignored due to complete cloud cover or (for nocturnal images) lack of
luminescence. We have developed a tool for automatically isolating
uninteresting images (primarily based on image histograms.) Uninteresting
images are tagged, which allows for them to be excluded from further
processing.
Our next tool is an automated system for isolating and measuring nocturnal
luminescence. This tool has been developed using images of St. Helens and
is being extended to work with other webcams where nightime lava glow have
been seen. The system works by first minimizing each camera's unique dark
current and amplification noise signals and then establishes if any pixels
fulfill a number of criteria that would indicate they are real "glow"
pixels.
A third tool integrates the webcam data into Google Earth, allowing the
height of plumes to be easily estimated and also the location of features
on the sides of the volcano to be accurately placed on to the
ground/GoogleMap surface. This tool makes visualization of multiple webcams
of a single volcano easy.
The recent eruptive phase of St. Helens has prompted the development of a
system for measuring 'dome growth'. A technique using stacks of images and
the Irani-Peleg super-resolution algorithm to estimate subpixel region
growth is being tested at the moment.
The final tool presented (currently under development) is a simple volcanic
plume finder. It works by analyzing the RGB histograms of key regions
around the volcano vent and flagging image statistics which indicate the
possible presence of steam. It is postulated that when adjusted for local
climatic conditions the amount of steaming may be indicative of change at a
volcano.
These techinques aim to move the analysis of webcam images into an
operational framework on a sound scientific footing.