What I want to do
A while ago I made a ndvi picutre with two canon a2500 cameras. NDVI canon a2500. No I finish my quadcopter after a major chrash and I started making NDVI images with two cameras of a farmers field yesterday afternoon. What I notice is that multiple images from the same spot have diffrent indexes.
My attempt and results
Setup: 1. Two canon a2500 running both chdk with remote sync enabled. 2. One camera unmodified. Other camera the IR filter removed and a 850nm filter placed infornt of the lens. 3. Both cameras have there shutter speed set to 1/200. 4. There was a thunderstorm, in my hast I forgot to turn on RAW, the images are jpeg. 5. NDVI was made with Ned tool. 6, Drone altitude 80 meters 7. Drone speed 5m/s 8. Below images where taken after each other during flight. 9. It rain the day be before. 10. The Images where taken arround 20:30. 11. The images have overlay in the vertical direction, first two you can see the small tree. In the second and third picture you can see the dark horizontal lines which are below the tree.
Questions and next steps
I made 72 images of the field. Most of them the colors are consistant, a little bit too red if you ask me. But here and there you see big diffrences in index colors, a spot may be red and in the another picutre the same spot is green. The question is why?? 1. Is it becuase I made the pictures at the end of the day where the sun was low on the horizon? 2. Shutter speed where lock. Did the camera for some reason decide change the white balance, iso? 3. Or these picutres do not mean anything because they are jpeg pictures and not raw. 4. Do I need to lock the ISO also. 5. Do I need to white balance the cameras??
Any other Ideas will help allot.
Tomorrow the forcast looks good. I will make pictures of the same field with the same setting at noon. See if the high sun maks any diffrence. Need to fix this else the farmer will not take me serious.