Public Lab Wiki documentation



GMF 2 infrared camera feature

This is a revision from June 18, 2012 19:00. View all revisions
3 | 13 | | #2541

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

1. Science background

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