This document summarizes Oliver Sonnentag's talk on using digital camera archives to study plant phenology beyond just canopy greenness. It discusses using cameras to estimate leaf area index and clumping based on gap fraction theory. It also explores using image texture and snow cover data from camera archives. The document concludes that while camera and format may not be important for canopy greenness, they could matter more for other phenology metrics like leaf area index that rely on analysis of image details and quality.

1. ACEAS 2014 Phenocam workshop, North Stradbroke Island, Australia
Possibilities for phenological research using digital
image archives: options beyond canopy greenness
© NASA
March 12, 2014
Oliver Sonnentag, PhD
Université de Montréal

2. 2Talk outline
• Canopy greenness
• Digital camera and image format choice for canopy greenness
• Beyond canopy greenness: CIE Y
• Beyond canopy greenness: digital cover photography (DCP)
• Beyond canopy greenness: texture
• Beyond canopy greenness: snow cover
• Summary and conclusions

3. 3Canopy greenness vs. field observations
(Jacobs et al., 2002, ACM GIS; Sonnentag et al., 2012, Agricultural and Forest Meteorology)

4. 3Canopy greenness vs. field observations
http://phenocam.sr.unh.edu/
(Jacobs et al., 2002, ACM GIS; Sonnentag et al., 2012, Agricultural and Forest Meteorology)

5. 3Canopy greenness vs. field observations
http://phenocam.sr.unh.edu/
http://amos1.cse.wustl.edu
(Jacobs et al., 2002, ACM GIS; Sonnentag et al., 2012, Agricultural and Forest Meteorology)

6. 4Digital repeat photography options
There are many options …

7. 4Digital repeat photography options
There are many options …

8. 5Digital camera choice for canopy greenness
Digital camera choice might not be of major importance for canopy greenness.
(Sonnentag et al., 2012, Agricultural and Forest Meteorology)

9. 6Image format choice for canopy greenness
(Sonnentag et al., 2012, Agricultural and Forest Meteorology; Verhoeven, 2010, International Journal of Remote Sensing)
Digital image format choice might not be of major importance for canopy greenness.

10. 7Beyond canopy greenness: CIE Y
(Sonnentag et al., 2011, Agricultural and Forest Meteorology)

11. 7Beyond canopy greenness: CIE Y
(Sonnentag et al., 2011, Agricultural and Forest Meteorology)
Digital camera and image format
choice might be of secondary
importance?

12. 8Beyond canopy greenness: DCP I
(Pekin and Macfarlane, 2010, Remote Sensing)

13. 8Beyond canopy greenness: DCP I
with:
φ =1− ff / fc
Lt = − fc ln(φ)/k
k = G(θ)/cos(θ)
Crown porosity:
Plant area index:
Clumping index:
(Pekin and Macfarlane, 2010, Remote Sensing)

14. 9Beyond canopy greenness: DCP II
(Ryu et al., 2012, Remote Sensing of Environment)

15. 9Beyond canopy greenness: DCP II
Time lapse photography
for DCP LAI phenology:
“good” quality digital
images from consumer-
grade point-and-shoot
digital camera (e.g., Canon
A-series)
(Ryu et al., 2012, Remote Sensing of Environment)

16. 10Beyond canopy greenness: DCP II
(Macfarlane et al., in review, Agricultural and Forest Meteorology)

17. 10Beyond canopy greenness: DCP II
(Macfarlane et al., in review, Agricultural and Forest Meteorology)
Digital image format choice might be of fundamental importance for DCP.

18. 11Beyond canopy greenness: DCP IV
At view angle of 57.5°:
(Baret et al., 2010, Agricultural and Forest Meteorology; Liu et al., 2010, Agricultural and Forest Meteorology)

19. 11Beyond canopy greenness: DCP IV
At view angle of 57.5°:
At view angle of 0° (nadir):
(Baret et al., 2010, Agricultural and Forest Meteorology; Liu et al., 2010, Agricultural and Forest Meteorology)

20. 12Beyond canopy greenness: DCP V
LAI=1.02 LAI=1.55

21. 12Beyond canopy greenness: DCP V
• Background color heterogeneity (forest: blue sky; crops: bare soil)
• Sphagnum color highly variable depending on species and wetness
• Differential phenologies: Sphagnum vs. vascular plants
• Very short dwarf/shrub canopy: almost no vertical stratification
LAI=1.02 LAI=1.55

22. 13Beyond canopy greenness: texture
(Proulx et al., 2008, Ecological Informatics; Proulx et al., 2009, Ecological Informatics)

23. 13Beyond canopy greenness: texture
(Proulx et al., 2008, Ecological Informatics; Proulx et al., 2009, Ecological Informatics)

24. 14Eddy covariance along a permafrost gradient
1000 km

25. 15NWT: snowmelt 2013

26. 16NWT: snowmelt 2013
Havikpak Creek (boreal forest; cont. permaf.)Trail Valley Creek (tundra; cont. permaf.)

27. 17
(Hinkler et al., 2002; International Journal of Remote Sensing)
Beyond canopy greenness: snow cover

28. 18Summary and conclusions
• Digital camera and image format choice might be of secondary importance for
monitoring vegetation status based on canopy greenness.
• Upward- and downward-looking digital cameras allow for the estimation of leaf
area index and clumping based on gap-fraction theory for which especially digital
image format choice might matter.
• Image texture and snow cover are promising approaches to make use of
growing digital image archives for which digital camera and image format choice
might be important.

29. 19Acknowledgements
• Andrew Richardson (Harvard University, USA)
• Dennis Baldocchi (University of California, Berkeley, USA)
• Matthias Peichl (Swedish Agricultural University, Sweden)
• Youngryel Ryu (Seoul National University, South Korea)
• Craig Macfarlane (CSIRO, Australia)
• Philip Marsh (Wilfried Laurier University, Canada)
• William Quinton (Wilfried Laurier University, Canada)
• Jennifer Baltzer (Wilfrid Laurier University, Canada)
Funding was provided by USGS, NSF, DOE (all USA) and CFI, FQRNT
and NSERC (all Canada).

30. THANKS!
© NASA
oliver.sonnentag@umontreal.ca