Video-derived Navigational and Recreational CSIs at Teignmouth

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Video-derived Navigational and Recreational CSIs
at Teignmouth
Mark Davidson University of Plymouth, UK Ismael
Marino-Tapia - University of Plymouth, UK
The CoastView Project
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Contents

• 1. Navigation
• Frame of reference.
• Algorithm development
• Location of channel marker buoys
• Location of navigation channel hazardous
  sandbars
• Associated CSI
• 2. Recreation (Bather safety)
• Frame of reference
• Location of bathing hazards
• Hydrodynamics (2HD model-aided waves currents)
• Hazardous sand bar location
• Associated CSI
• 3. Information delivery (Web Page)
• Week to a page
• Last six Springs
• Met-Ocean data

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The frame of reference
Long-term management vision policy
Describes how part, or all of the strategic
objective will be achieved in a four-stage process
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Frame of reference Navigation at Teignmouth
Improve maritime safety and avoid human,
economical and ecological disasters
To ensure that the buoys accurately mark the
channel perimeter to minimize the possibility of
ships going aground
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Improve maritime safety and avoid human,
economical and ecological disasters

• Vessels grounding on sandbanks and reefs
• Inappropriate position of channel markers and
  poor signalling of hazards
• Buoys drag and move from original position
  (specially during storms)
• Bottom accretes and channel position changes

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Improve maritime safety and avoid human,
economical and ecological disasters

• Vessels grounding on sandbanks and reefs
• Consequences

Where When How Consequences
Santa Fe, Galapagos I., Ecuador Jan 2001 Ran aground while steering into harbour 3 million litres crude oil spilled.
Karachi, Pakistan July 2003 Stranded on channel perimeter at entrance of port Ship broke, spilling 12,000 15,000 tons of crude oil. Biggest spill on Pakistan history
Back
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To ensure that the buoys accurately mark the
channel perimeter to minimize the possibility of
ships going aground

• Navigational problems at Teignmouth
• Sanbanks and channel are very dynamic features
• Difficult to position buoys adequately relative
  to channel
• Hence to maintain an effective dredging strategy

• In the past there have been a few cases of ship
  grounding at the site.
• Our aim is to help the manager avoid a
  potentially catastrophic situation

Back
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Video recognition of navigation channel markers

• Topics to cover
• Algorithm for extraction of buoy position.
• Concept
• The algorithm at work

• Examples of data retrieved and data quality
  considerations

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Video recognition of navigation channel markers

• Algorithm for extraction of buoy position The
  concept
• Visual characteristics of buoy vary greatly
  depending on Ambient light, tidal stage, poor
  visibility (rain, fog), obstructions, etc.

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Video recognition of navigation channel markers
Algorithm for extraction of buoy position The
concept

• Reduce the search area
• Isolate red band
• Detection of buoy
• ifindmax(Iµ(x) Imin(x))y
• 4. Transform oblique coordinates to planview
  (XYZtide to UV)

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Video recognition of navigation channel markers
Extraction of buoy position Algorithm at work
CAMERA 4 Inner buoys
CAMERA 5 Outer buoys
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Video recognition of navigation channel markers

• Extraction of buoy position Algorithm at work
• Method is not infallible
• But is simple and robust

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Examples of data retrieved Buoy 2
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Data quality considerations Buoy 4

• Highly non-stationary time series (variance
  changes and level shifts).
• VERY gappy structure (only day time, depends on
  image quality)
• Traditional methods for outlier removal dont
  work (differentiation, FFT filtering, moving
  averages, etc.)

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Data quality considerations Buoy 4

• Wavelet analysis
• Specially useful for treating non-stationary time
  series.
• Analysis in the time-frequency domain
  (identifies time of variance change at a given
  frequency.

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Data quality considerations Buoy 4

• Routine for outlier removal
• Outliers located at energy peaks but use
  derivative to aid in the identification process.
• Before modification value needs to be compared
  with a local average to avoid data erosion.

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A Navigation CSI

• An interactive tool that allows
• Calculation of buoy sandbank interdistace
• Geographical location (in useful coordinates)
  of channel entrance
• Could function as a guide for dredging activities

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Concluding remarks Navigation CSI

• Finish outlier removal technique (wavelet,
  derivatives and moving averages)
• Make algorithm for buoy detection operational
• Create data base for life of the Argus station at
  Teignmouth
• Obtain (IBM?) fixed intertidal contour
• Program the interactive tool for CSI calculation/
  assessment

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Frame of reference Recreation at Teignmouth
Risk maps
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Bathing Hazards

• Flow patterns from numerical model
• Siegle, E. 2003 used hydrodynamic model MIKE 21
  and video-extracted bathymetries to model flow
  patterns under different morphological set-ups.
• Location of hazardous sandbanks
• Using rectified images, hazardous sandbaks where
  beach users might be cut off as tide rises can be
  identified.

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Bathing Hazards

• Risk maps
• Use numerical model realizations and rectified
  images of system at low tide to generate
  simplified risk maps given a morphological
  configuration.

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Concluding remarks Recreation CSI

• Simple concept easily accomplished
  (preliminary?)
• Manager has interest of implementing it on summer
  2004
• Possibility of following the whole frame of
  reference in practice.