Thanks for all of the great discussion on my last post about the DVI vs. NDVI vegetation indices. We have done a lot more work in the area and have come to a pretty strong conclusion that, for our purposes and equipment, DVI images really nail exactly what is going on on the ground. We've now seen excellent results over dozens of fields and several different crops. I wrote up some of our most recent results on our website at http://agribotix.com/blog/2014/7/3/agribotix-images-an-x-ray-for-yo... so check it out if you're interested.
One thing I didn't mention in the blog post because I didn't want to get bogged down in the details is that NDVI is very sensitive to moisture. In the side-by-side image of the barley farm, the pivot was watering and was somewhere near the road at the bottom. I believe that the large vertical artifact just to the west of the road is due to that crop being very wet. We also observed this when flying elsewhere where a recently plowed fallow field has a low NDVI signal as it should, but a drier fallow field actually has quite a strong signal. That said, I spent several hours at this field with both georeferenced images pulled up on my iPhone and the intensity of the NDVI signal had essentially zero correlation between what I saw on the ground while the DVI signal was just perfect.
Mr Mckinnon with what software can i process DVI rather than the NDVI?
Sorry for the delayed reply. I just got back from a backpacking trip where I was off the grid. I use a Fiji script I've written that was explained pretty well in a previous post that I've reattached here. It will do both NDVI and DVI on a folder of images using either the green or the red as the visible channel. Alternatively, Ned Horning has incorporated DVI into his app that has a nice GUI and is probably easier to use. That is available at http://publiclab.org/notes/nedhorning/06-24-2014/updated-photo-moni.... I haven't used his updated version yet, but it should do the trick the same as my plugin.
Mr. Daniel thanks. Although right now im still working on orthoimages rather than precision farming. The last one is on my work queue, so again thank you. and i will report my results to you then.