can_eye 1/11 the can_eye software for processing digital hemispherical photos f. baret, m. weiss
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![Page 1: CAN_EYE 1/11 The CAN_EYE software for processing Digital Hemispherical Photos F. Baret, M. Weiss](https://reader030.vdocuments.us/reader030/viewer/2022032706/56649e3b5503460f94b2db2d/html5/thumbnails/1.jpg)
CAN_EYE 1/11
The CAN_EYE software for processing Digital Hemispherical Photos
F. Baret, M. Weiss
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CAN_EYE 2/11
How to derive LAI from gap fraction
• fCover= 1-Po(0)
• fAPAR(s)fIPAR(s)=1-Po(s)
•
)cos(/).()( LAIGePo
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CAN_EYE 3/11
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50
0.1
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1
LAI
Po(
57;5
°)
)cos(/).()( LAIGePo
The LAI Po relationship
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CAN_EYE 4/11
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-2.5
-2
-1.5
-1
-0.5
0
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1.5
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2.5
LAI
LAI(
Po)
-LA
I(P
o+er
ror)
Uncertainties in LAI estimates
-0.08-0.04
-0.02
-0.01
0.08
0.04
0.02
0.01
Error on Po
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CAN_EYE 5/11
Start Setup Imageselection
Preprocessing
Classification EndProcessing & reporting
CAN_EYE: suite of steps
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CAN_EYE 6/11
Some results over Barrax
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INRA-CSE
Un
iver
sity
of
Val
enci
a
Comparison of 2 independent processing
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CAN_EYE 7/11
Comparison with other methods
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PAI destructif
PAI v
rai C
an_e
ye
Maïs Tournesol Soja Blé
r = 0.917
Comparison with LAI2000 over BarraxBy B. Martinez
Comparison with destructive measurements by V. Desmarez (CESBIO)
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CAN_EYE 8/11
The P57 photosUsing only the 57° direction allows to get better resolution
But no more access to fAPAR (except at tetas=57°!) and fCover
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CAN_EYE 9/11
Evidence of finer resolution
Hemispherical photosP57 photos
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CAN_EYE 10/11
Some results
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CAN_EYE 11/11
Conclusion• Software available (for free) (www.avignon.inra.fr/can_eye)• Advantages:
– Quick and easy to use– Accounting for clumping in LAI– Provides estimates of fAPAR and fCover– Traceability of the processing– Some encouraging validation results
• Potential problems:– Importance of illumination conditions: diffuse for looking down-ward– Potential problems when small gaps (resolution)– Not yet full documentation and references!!
• Future enhancements– Inclusion of Chen’s/Leblanc/Fernandes clumping computation– Processing P57 photos– Slope correction– More validation
• Development of autonomous light sensors (dynamics)