Post on 12-Mar-2021
9/10/2013
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Won Suk “Daniel” Lee
Professor
Agricultural and Biological Engineering
University of Florida
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Non‐destructive sensing technologies Near‐infrared spectroscopy (NIRS) Time‐resolved reflectance spectroscopy (TRS) Machine vision Multispectral / hyperspectral imaging Magnetic resonance imaging (MRI) Fluoroscopy with X‐ray
Applications NIRS applications Disease detection: citrus greening / citrus black spot X‐ray & MRI: fruit seed count
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Reflected or
Emitted
TransmittedAbsorbed
Incoming energy
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Spectrometry measures information related to the chemical composition of the materials with the wavelength
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Wavelength (nm)
Ref
lect
ance
(%
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Tangelo
HamlinValencia
Average fruit spectral reflectance over a
growing season from July to January
(Kane & Lee, 2006)
The concentration of an absorber is directly proportional to the sample absorbance
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Wavelength (nm)
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lect
ance
(%
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12 July 2005
20 Sept 20052 Nov 2005
13 Dec 2005
(Kane & Lee, 2006)
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Stepwise multiple linear regression
Principal component regression (PCR)
Partial least squares (PLS) regression
Hierarchical dimension reduction
Kullback‐Leibler divergence (KLD)
…
Develop prediction models (calibration)
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Applications:
Crop properties (nutrients, water, disease)
Soil properties (organic carbon, moisture, mineral nitrogen, phosphates, pH, particle size)
Weed detection9
A widely used tool for detecting soil and crop properties utilizing spectral signatures
Advantages: non‐destructive measurement and easy sample preparation
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White & red grapefruits from Florida, ‘Honey’ tangerines
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Valencia & Hamlin oranges, Thompson red grapefruits
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Healthy Healthy Symptomatic Symptomatic
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Reflenctance (%)
Wavelength (nm)
Healthy 1
Healthy 2
Black spot 1
Black spot 2
Black spot 3
Black spot 4
Black spot 5
Black spot 6
Black spot 7
Avg of Healthy
Avg of Black spot
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Most commonly used method for quality evaluation
Cost effective
Mature technology
Still needs more improvement for actual applications
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(Valero et al. 2004)
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Using the light diffusion theory, light absorption and scattering coefficients are obtained.
Simultaneous determination of chemical concentration & firmness
More novel than standard spectroscopy
Need a photon counting sensor (~$25,000)
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(Valero et al. 2004)
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32 cherries / sec
http://www.gpgraders.com.au/products/cherry‐grading/
30 images / cherry
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OriginalHue
Hue thresholded and inverted
Fruit only
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(adapted from
Dewdney, 2012)
Final result Original
Sat. thresholded and invertedHue thresholded and inverted
‘AND’
=
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Reflectance for various objects in a citrus grove
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Wavelength (Nm)
Re
flect
an
ce (
%)
Big leafCitrusSmall leaf
815 nm
1190 nm
+ = ?
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(Source: http://www.sciencedirect.com/science/article/pii/S003442570900073X)
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Common applications – yield mapping, nutrient & disease detection, water stress, …
Immature green citrus fruit detection
Citrus greening disease (HLB) detection
Blueberry fruit detection
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Actual fruit locations
Pixel segmented image
Detected fruitHyperspectralimage
RGB image
Okamoto, H., and W. S. Lee. 2009. Green citrus detection using hyperspectral imaging. Computers and Electronics in Agriculture 66(2): 201‐208.
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(Source: R. Ehsani)
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Hyperspectral imaging combines images with spectral information.
Multispectral imaging is more suitable for practical applications due to cost and processing time.
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How MRI works? (2.5 min.)(http://www.youtube.com/watch?v=pGcZvSG805Y)
(Source: http://insideinsides.blogspot.com/2010/07/orange.html)
Orange
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(Source: http://insideinsides.blogspot.com/2010/12/persimmon.html)
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Non‐invasive & non‐destructive method
Not suitable for conveyor systems
Takes long time for imaging
Need much maintenance
Safety Strong magnetic field ‐ avoid any metal objects!
Heating caused by radiowave absorption
Cost Conventional system: $1 – 3 million
Portable unit (Prepolarized MRI): $50,000 (http://www‐
mrsrl.stanford.edu/research.html#top)
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X‐ray imaging technique for acquiring real‐time moving images
Low energy is sufficient for agricultural crops
Instrument: less than $100,000
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(Source: http://spie.org/x84974.xml, 2012)
Seed
“Not possible to discriminate between seeds and pulp consistently using CT or x‐ray images because of their similar densities…”
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(Source: http://spie.org/x84974.xml, 2012)
• 0.2 T used• Took 7 sec
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Many non‐destructive sensing technologies are available
Each has its own advantages and limitations
NIRS, multispectral imaging, and X‐ray have great potential and promising…
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