The CAN_EYE software for processing Digital Hemispherical Photos

1
The CAN_EYE software for processing Digital
Hemispherical Photos

• F. Baret, M. Weiss

2
How to derive LAI from gap fraction

• fCover 1-Po(0)
• fAPAR(qs)?fIPAR(qs)1-Po(qs)

3
The LAI Po relationship
4
Uncertainties in LAI estimates
0.08
0.04
0.02
0.01
-0.01
-0.02
-0.04
Error on Po
-0.08
5
CAN_EYE suite of steps
Start
Setup
Image selection
Preprocessing
Classification
End
Processing reporting
6
Some results over Barrax
Comparison of 2 independent processing
7
Comparison with other methods
Comparison with LAI2000 over Barrax By B. Martinez
Comparison with destructive measurements by V.
Desmarez (CESBIO)
8
The P57 photos

• Using only the 57 direction allows to get better
  resolution
• But no more access to fAPAR (except at
  tetas57!) and fCover

9
Evidence of finer resolution
10
Some results
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 Chens/Leblanc/Fernandes clumping
  computation
• Processing P57 photos
• Slope correction
• More validation
• Development of autonomous light sensors (dynamics)