Making sense of methane fluxes with MATLAB

Gavin McNicolEPS 209

Data source – Jaclyn Hatala & Dennis Baldocchi

Field Site & Method

Sherman Island,Sacramento- SJ Bay Delta

Collaboration with Baldocchi lab

Eddy covariance flux measurements CH4 CO2 H2O

Diurnal methane fluxes

Source: Jaclyn Hatala & Dennis Baldocchi

Cow Cam!

Source: Detto et al. (2010)

MATLAB Image Processing

Basic Goals:Find cows in image (color, texture, intensity)Produce vector of ‘cow’ and ‘no cow’ time pointsCan we do more than just presence/absence?

Results so far

• Individual images: can we see the cows?Range Filter

Results

• Individual images: can we see the cows?Mahalanobis distance

Results

Range filter method on test images: 59% accuracy (type I error)

Threshold

Results

Unexpected result 18th – 25th January 2010

Next steps

1 – Combine mahalanobis distance information with edge detector

2 – Better to over-predict.

3 – Group photos by day as cows are never there all day and look at deviation from mean intensity.

Questions?