Image above: Wheat seedlings from above in normal color (RGB), false color infrared (NRG), and normalized difference vegetation index (NDVI).
My last flight of the day on iFarm Saturday was over Dorn's field trial of seven wheat varieties. As the dual camera infrared KAP rig snapped synchronous pairs of visible and near infrared photos every 10 seconds, a handheld NDVI scanner was making a transect across the field. Maybe we will be able to compare results someday. It was probably a little early in the season to make good comparisons because the wheat plants are still small and most of the view from above is soil. So a spatially integrated NDVI value will mostly be averaging NDVI values for soil which have little meaning. However, the average NDVI value will be higher where the plants are larger and denser, so some measure of wheat biomass per area is possible. Maybe Dorn can outline on one of these images where each variety is and what their names are. I hope the goal is to grow the most fabulous wheat berries ever, but it's probably not possible to improve on the ones in the salad Dorn served us later.
Shadows do not seem to affect the NDVI values in this close-up view of wheat seedlings.
We have noticed that the single camera NDVI images often have anomalously high NDVI values where it is shady. So it was good to see that the dual camera system can sometimes handle shadows well. Although the late afternoon shadows are conspicuous in the RGB and NRG images, they disappear in the close-up NDVI image above. However, in the more distant photos used in the big image at gigapan below, the shadows of people and the tree have higher NDVI values (click the snapshots). I am not sure how to explain the difference.
The missing image below can be seen here: http://www.gigapan.com/gigapans/130558/
RGB: Normal color photo from the unmodified camera. NIR: The photos from the modified near-infrared camera. NRG: A near-infrared channel from the modified camera is displayed as red, red and green channels from the unmodified camera are displayed as green and blue, respectively. NDVI: Normalized difference vegetation index. For each pixel, NDVI=(NIR-red)/(NIR+red).