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Recent Argus DevelopmentsIn North America

Rob HolmanSECNAV/CNO Chair in Oceanography

Oregon State University

• Tessellation Arrays and NCEX

• Sensor Quality and Resolution

• Objective Focusing

• Recent Stereo Results

• Argus III

• Cross-geom Hurricane Isabel, Duck, 09/18/03

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Note that these techniques are in development and aren’t yet available for release.

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Argus and the NCEX Field Experiment

NCEX = Nearshore Canyon Experiment,

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NCEX Argus Coverage

C1

C2

C3

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Pixel Instrument Coverage (example)

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Packing of Alpha Arrays into a

Tessilation Tile

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shoreline

NCEX Tessellation Array

Resolution limited (5 m)

1842 pixels

tile

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Directional Spectrum Example

f < 0.33 Hz, k-2 normalized.

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Tessellation Arrays

• Produce wave directional spectrum at any location

• Query at an array of locations

• Extract simple statistics (peak direction?)

• Use same lag array for depth estimation

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NCEX Array, 09/03

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NCEX Array, 09/03 (blow-up)

Runup

“Old” Bathy Line

Vbar

Tess(alpha and bathy

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Vertically-displaced Stereo

C1, z = 43.1 m C1, z = 28.2 m

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Stereo Profile Test Update

08/14/03

Survey courtesy of the FRF

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Lens Quality

Modulation Transfer Function (MTF)

•Ratio of the spectrum of a sensed signal to the source

•Measures the quality of the CCD chip as well as the lens

•Test image is random noise image (looks gray)

wavenumber

Spec

tra

dens

ity

1.0

wavenumber

Spec

tra

dens

ity

1.0

Ideal Real

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Modulation Transfer Function (MTF)

not

Scaled to show number of “effective pixels” at roll-off Effect of “sharp” setting

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Objective Lens Focusing?

Can we use the spectral fall-off in an image to tell when the focus of a lens is optimum?

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Objective Lens Focusing

Focus was slowly adjusted through a sequence of images

+

+

+

+

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Argus III Upgrade (North America)

Argus II Argus III

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Argus Collection Strategies

Argus II Argus III

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Crossgeom

GCP’s in viewNo GCP’s

AutogeomCrossgeom

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Crossgeom

Use overlapping, high-contrast area of snapshots as temporary template (requires Argus III for synchronous snaps)

Longshore Current?

x, cross-shore

y, alongshore

v, longshore current

Field Test

• Mean currents

Field Test

smvrms

vvv

diff

isdiff

/10.0)( =

−=

Field Test

• Surface dynamics– Alongshore wind

stress

– Alongshore roller stress

ivyad

windy wwC ρτ =

)sin()sin(9.0 20 αβρτ sr

yroller Hg=

y

sv

diffvz

Field Test• Alongshore wind stress

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Questions?

Not a hurricane Hurricane