README % C. Chickadel, chickadel@apl.washington.edu - 08 May 2018

These Matlab .mat files contains thermal infrared (IR) data mosaics Filenames are of the form:

INNERSHELF_2017Oct11_IR_mosaicked.mat (IR imagery of the larger scale study site)
INNERSHELF_2017Oct11_IR_mosaicked_focus_test.mat (IR imagery of the specific region imaged that day)

The variable in the IR image files (ends in "mosaicked") are:

name:         size (examples):       description:
  NT           4081x1751x30  		image scale factor
  ST           4081x1751x30  		unscaled raw IR image data (about 250 counts/degree)
  STC          4081x1751x30  		scaled raw IR image data
  W            4081x1751     		ignore, processing by product
  Xs           4081x1751     		easting grid coordinates (MGRS-UTM, meters)
  Ys           4081x1751     		northing grid coordinates (MGRS-UTM, meters)
  time            1x30      		center (average) time in epoch for each transect
  compMap                           composite maps of multiple passes
  cTime                             center (average) time in epoch for each compostie map (compMap)


NOTE:

1. epoch time is the seconds since 1970 Jan 1 0000 UTC.  Use the functions
epoch2Matlab.m and matlab2Epoch.m to convert to and from Matlab's datenum.

2. there are some empty IR maps due to the nature of the processing, please ignore.

% example Matlab script to display the infrared (IR) temperature maps
for j = 1:length(time)
  clf
  imagesc(Xs(1,:)/1000,Ys(:,1)/1000,STC(:,:,j))
  colorbar
  title(datestr(epoch2Matlab(time(j))))
  xlabel('E [km]')
  ylabel('N [km]')
  axis image xy
  pause
end


3. The IR data have not been calibrated (yet) to temperature or corrected for camera drift. The latter effect often results in large scale changes in mean temperature, so for the Inner Shelf project this can manifest as a N-S increase or decrease in temperature for each mosaicked strip. For now, it's best to use a this as a relative temperature indicator (remove a mean and use the 250 count/degree response to get an approximation of local dT).