Jeff W/Chris F working on this feature for the upcoming Grassroots Mapping Forum:

1. Science background

• base on Chris' page: http://publiclaboratory.org/wiki/ndvi-plots-ir-camera-kit
• Is this your illustration: https://www.flickr.com/photos/jeffreywarren/5416397210/? We could modify that for B&W
• NIR by itself looks cool but does not highlight meaningful patterns well.
• NRG is false color IR with vegetation in shades of red and pink
• NDVI highlights areas of high or low photosynthetic activity

2. A second camera to capture NIR

• How to modify a camera (YouTube vid, illustrations)
• How to mount two cameras
• image heavy section...

3. Triggering the cameras in flight

• Simple version: rubber bands or independent intervalometers/CHDK
• Advanced: Simultaneous triggering makes post-processing much easier
  • CHDK to enable synchronous remote via USB on Canon Powershots
  • USB cable mod, MK111 timer

4. Matching and compositing images

• Synchronize the cameras’ clocks
• Capture jpgs
• Identify NIR/VIS photo pairs via timestamps
• Use Ned’s Fiji macro (requires well-overlapped, sharp photos, and good organizational skills)
• Make structure from motion models in Hypr3D
• Stitch images in MS ICE or GIMP
• Align images over a georeferenced map with MapKnitter

Advanced: To produce more precise results (link to web page):

• Synchronize the cameras’ clocks
• Capture RAW, convert to Tiff (need CHDK, big partitioned cards, RAWTherapee (e.g.), big hard drive)
• Identify NIR/VIS photo pairs via timestamps
• Use Ned’s Fiji macro
• Interpret pixel-level results (or almost)
• Make structure from motion models in Hypr3D or 123D Catch
• Stitch images in MS ICE, GIMP, or Agisoft PhotoScan (allows GPS control)
• Align images over a georeferenced map with Mapknitter

5. Interpretation

• One-time maps can reveal side by side differences in plant growth or health (Lee, NH)
• Time series of NDVI can reveal seasonal or year to year trends in plant growth and health (TBD)
• examples?

6. Conclusion

• online resources
• how to get involved