Public Lab Research note


Moody Meadows

by cfastie | November 25, 2013 18:10 | 4,619 views | 0 comments | #9824 | 4,619 views | 0 comments | #9824 25 Nov 18:10

Read more: stable.publiclab.org/n/9824


I photographed the scene above of the Moody Meadows farm in New Haven, VT with Canon A2200 Powershots outfitted with either Wratten 25A and Schott BG3 filters.
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FarmShade6pan2k.jpg
Results for the Wratten 25A (top row) and Schott BG3 (bottom row). Photos from the cameras (left), false color IR (middle), and NDVI (right). BGR indicates that the red and blue channels have been swapped from the original RGB. RBG indicates that the blue and green channels have been swapped from the original RGB.
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Notes:

  • Wratten 25A and BG3 cameras were custom white balanced using red and blue origami paper, respectively.
  • Channel swapping in the BG3 false color image was actually equalizing the blue and green channels by making them both 70% green and 70% blue.
  • Stretch parameter for both NDVI images in the Fiji plugin was 5 for both channels.
  • To make the BG3 NDVI image similar to the Wratten 25A, 35 was subtracted from the DNs in the BG3 NDVI image.

Conclusions:

  • The Wratten 25A NDVI does a better job delineating the border between the upper, closely mowed field and the lower field.
  • The Wratten 25A NDVI does a better job discriminating between the buildings and green plants.

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