May 28, 2017

Project: High resolution topographic features controlling water retention in agricultural landscapes, Iowa (part of Intensively Managed Landscapes Critical Zone Observatory)

Objective: Capture resolutions of less than 2-cm with UAS and terrestrial lidar following a heavy rain event on two farm plots with differing slopes and land practices

Flight Date: May 21-25, 2017

Flight Location: Near Williamsburg, Iowa at Maas (large slope variation) and Trimpe (low slope variation) farms

Airframe: Phantom 4 Pro

Sensors: Phantom 4 Pro camera

Crew: Michael Wing, Chris Sladek, and henry pai

Outcomes:
  •  Successful flights at both farms
    • Maas (May 22) and Trimpe (May 23) flight characteristics
      • 30 m altitude
      • 2.9 m/s
      • Cross-grid pattern, 40-50 minute total flight time (~20 min per battery)
      • 0.8 cm resolution
      • >1000 images
  • Comments
    • Phantom 4 Pro handled heavy winds quite well (on May 22)
    • Only pushed Phantom 4 Pro to 30% battery warning
    • Return to launch feature more reliable than pilot control in heavy winds
    • Issues with tablet obtaining live view using UgCS for DJI app
      • Tablet was only 2.4 GHz capable 
      • Changed Connectify (wifi hotspot) setting so that 2.4 GHz device could connect
      • Worked on Chris's cell phone (may be only dual band device; 2.4 & 5 GHz)
      • Check Android OS versions
      • Email UgCS for any updates
    • Issues with blurry images
      • Initial settings for shutter priority set in DJI Go app (ISO 200, shutter 1/1000 sec)- blurry
      • Changed settings to Auto (ISO 200) and image quality was good (ISO 400 was washed out)
      • Test Auto (ISO 100); could not see red tape on white lids while visible on blue (Maas site with blue and white target in same frame seen below)

    • Issues with continuing mission on power down
      • When replacing battery, mission was not found on Phantom 4 Pro
      • Email UgCS about DJI functionality with "Continue" mission feature
    • Issues on takeoff from ground software?
      • At Trimpe, takeoff caused one flip (slow motor ramp up then flip on take off)
      • Adjusted for faster vertical takeoff speed but still slow motor ramp up
      • Removed takeoff command and takeoff & mission completed without issue; though hard to predict initial waypoint
    • Logistics were challenging given target requirements for both terrestrial lidar and UAS requirements
    • Locus Map Free remains a workhorse app for my phone for laying out targets, importing kml polygons and points, and saving survey points
      • Recommend bringing battery packs for phone for all-day app usage
    • Generous hotel wifi (500 mb/s upload) allowed for data to be uploaded (~3-4 hrs) on work desktop and initial alignment and DSM reconstructions for next-day assessments

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