The CAN_EYE software for processing Digital Hemispherical Photos
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Transcript of The CAN_EYE software for processing Digital Hemispherical Photos
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The CAN_EYE software for processing Digital Hemispherical Photos
F. Baret, M. Weiss
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How to derive LAI from gap fraction
• fCover= 1-Po(0)
• fAPAR(s)fIPAR(s)=1-Po(s)
•
)cos(/).()( LAIGePo
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)cos(/).()( LAIGePo
The LAI Po relationship
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LAI
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Uncertainties in LAI estimates
-0.08-0.04
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Error on Po
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Start Setup Imageselection
Preprocessing
Classification EndProcessing & reporting
CAN_EYE: suite of steps
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Some results over Barrax
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INRA-CSE
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sity
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Comparison of 2 independent processing
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Comparison with other methods
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PAI destructif
PAI v
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an_e
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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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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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Evidence of finer resolution
Hemispherical photosP57 photos
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Some results
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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)