Mapping echoes: the acoustics of riverbed and shallow seafloors

3 April 2018 Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 1/41
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Co-conspirators • Paul Grams, U.S. Geological Survey Grand Canyon Monitoring
& Research Center • Matt Kaplinski, Sandbar Studies Unit, NAU-SESES Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 2/41 2/41

Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 3/41 3/41

• 1999: 100% surface topography of Mars by NASA’s Mars
Orbiter Laser Altimeter • 2018: estimated 7 —18% of Earth’s ocean floor mapped at same resolution • 2018: launch of ‘Seabed 2030’ (GEBCO / Nippon Foundation) Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 3/41 3/41

Acoustic remote sensing Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 4/41
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Acoustic benthic habitat mapping Fonseca et al. (2009) Applied Acoustics

Acoustic benthic habitat mapping Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18
5/41 5/41

Shallow water was technically difficult Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 6/41 6/41

Now, only logistics stand in our way Daniel Buscombe. [email protected]
NAU-SICCS Seminar, 4/3/18 7/41 7/41

The world’s shallow water: continental shelf • ≈10% < 150
m average depth • water absorbs > 50% of visible light energy within 10 m Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 8/41 8/41

The world’s shallow water: lakes • Cæl et al. (2017)
• 278,966,646 lakes • ≈99.9% < 10 m average depth Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 9/41 9/41

The world’s shallow water: rivers • Andreadis et al. (2013)
• 3,458,785 rivers • ≈85% < 1 m average depth Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 10/41 10/41

Shallow water is disproportionately important • Biodiversity Daniel Buscombe. [email protected]

Shallow water is disproportionately important • Biodiversity • Sediment transport

• Economy Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 11/41 11/41

• Economy • Human society: 40% global pop. within 10m of sea level (UN, 2007) Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 11/41 11/41

Acoustics in shallow water are different Classical scattering theory not
applicable: • Bed is acoustically rough Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 12/41 12/41

applicable: • Small beams Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 12/41 12/41

applicable: • Small footprints = too few scatterers Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 12/41 12/41

applicable: • Significant topographic ‘contamination’ of the backscatter signal Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 12/41 12/41

applicable: • Deterministic physics out of favour Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 12/41 12/41

Data-driven substrate classification Hassan et al. (2014) PLoS-ONE Daniel Buscombe.
[email protected] NAU-SICCS Seminar, 4/3/18 13/41 13/41

Probabilistic approaches • y∗ = arg max y∈M P(x|y)P(y) =
arg max y∈M P(x, y) • Modeling P(x, y) → generate x Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 14/41 14/41

Probabilistic approaches • y∗ = arg max y∈M P(y|x, θ)
• Bypasses P(x, y) (complicated) but task-specific • ANN, SVM, RF, etc Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 14/41 14/41

Colorado River in Grand Canyon Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 15/41 15/41

Gaussian Mixture Model P(x|λ) = M ∑ m=1 wm g(x|µm
, Σm ) • conditional probability of backscatter given λ • per-substrate weight • Gaussian pdf Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 16/41 16/41

Gaussian Mixture Model Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 16/41
16/41

Filtering the topographic contamination Buscombe et al. (2017) Journal of
Geophysical Research Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 17/41 17/41

Filtering → ‘compositional backscatter’ Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18
18/41 18/41

Backscatter vs. substrate Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 19/41
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GMM results Buscombe et al. (2017) Journal of Geophysical Research

GMM performance Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 21/41 21/41

Colorado River, RM - 4.6 Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 22/41 22/41

Multispectral Backscatter Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 23/41 23/41

Bedford Basin, Nova Scotia Buscombe & Grams (in review) IEEE
Geo. & Rem. Sens. Letters Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 24/41 24/41

Patricia Bay, British Columbia Buscombe & Grams (in review) IEEE
Geo. & Rem. Sens. Letters Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 25/41 25/41

Backscatter vs. Substrate Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 26/41
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Conditional Random Field PΦ (x, y) = I ∏ i=1
ϕi Di ZΦ (x) = ∑ y PΦ (x, y) P(y|x) = 1 ZΦ (x) PΦ (x, y) P(y|x, θ) = 1 ZΦ (x) exp( −E(y|x, θ) ) Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 27/41 27/41

Fully-Connected Conditional Random Field E(y|x, θ) = ∑ i ψi
(yi, xi |θ) + ∑ i<j ψij (yi, yj, fi, fj |θ) • unary potentials • pairwise potentials Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 28/41 28/41

Unary and pairwise potentials ψij (yi, yj, fi, fj |θ)
= Λ(yi, yj |θ) L ∑ l=1 kl (fl i , fl j ) kl (fl i , fl j ) = exp      − |xi − xj |2 2θ2 β      +exp      − |pi − pj |2 2θ2 γ      • compatibility function • proximity tolerance Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 29/41 29/41

CRF result, Bedford Basin Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18
30/41 30/41

Multispectral vs. Monospectral Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 31/41
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CRF performance Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 32/41 32/41

Generative vs. Discriminative Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 33/41
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Deterministic Unary Potentials Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 34/41
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CRF refinement Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 35/41 35/41

Summary • Acoustic RS poised to explode in shallow water

Summary • Acoustical problems in shallow water can be overcome

Summary • Machine learning for substrate classification Daniel Buscombe. [email protected]

Summary • New discriminative algorithm Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 36/41 36/41

Summary • Hybrid physical-statistical modeling Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 36/41 36/41

Thanks! Questions? Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 37/41 37/41

This slide is intentionally blank Daniel Buscombe. [email protected] NAU-SICCS Seminar,
4/3/18 38/41 38/41

Computing backscatter from echœs • Raw echo (what we measure)
BS(θ) = EL − SL + 2TL − Af • 10 log 10 of ratios between a quantity and a reference quantity of acoustic pressure of 1 µ Pa • Source level [MEASURED] • Transmission losses [ESTIMATED] • True area of beam footprint [ESTIMATED] Amiri-Simkoœi et al., JASA, 2009; Buscombe et al., JGR, 2014 Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 39/41 39/41

Modeling the signal footprint • model using the sonar geometry
Buscombe et al., JGR, 2014 Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 40/41 40/41

Modeling the signal footprint • correct using scaling factor =
f(small scale roughness) Buscombe et al., JGR, 2017 Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 40/41 40/41

What’s next? Daniel Buscombe. [email protected] NAU-SICCS Seminar, 4/3/18 41/41 41/41

Mapping echoes: the acoustics of riverbed and s...

Mapping echoes: the acoustics of riverbed and shallow seafloors

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