Evan Hockridge

Thomas Gonya

Todd Horn

The Impacts of Altitude on High-Resolution Multispectral Remote Sensing for Hardwood Forest Species Delineation

Hardwood forest inventory is a time consuming and expensive process, especially for small forest owners (Cite). To expedite the process, satellite remote sensing techniques have been used with limited success due to low spatial resolution; unless expense high-resolution satellite data is purchased (Immitzer et al., 2012). Recent studies have shown that unmanned aerial systems (UAS) can be a means to collect affordable high-resolution forestry data that is as accurate as traditional ground surveys in the Central Hardwood Forest region of the United States (Hockridge, 2018). However, to fully match the quality of ground surveys, UAS remote sensing methods will need to successfully delineate species of trees in the imagery.

Our project seeks to identify tree species through UAS multispectral imagery utilizing the RedEdge Altum sensor integrated on the C-Astral Bramor ppX airframe. The sensor’s access to the LWIR and NIR bands and aircraft’s low altitude flight capability should allow for species specific spectral signatures to be identifiable. The aircraft will be flown at forested sites local to the West Lafayette, IN region at approximately 300 feet. It is unknown how much flight altitude’s effect on spatial resolution will impact the accuracy of the species delineation, so the Altum sensor will also be mounted on a fixed wing manned airplane that will fly surveying transects at altitudes of 2,000 and 3,000 feet so that data can be compared. The airborne datasets will be processed into multi-band orthomosaics and then analyzed to determine indices that can be used to identify tree species. From there, maps of tree species will be generated for both manned and unmanned aircraft data, and the accuracy associated with different spatial resolutions will be assessed when compared with ground surveys of tree species. From this, an ideal altitude for tree identification can be determined.

References

Immitzer, M., Atzberger, C., & Koukal, T. (2012). Tree Species Classification with Random Forest Using Very High Spatial Resolution 8-Band WorldView-2 Satellite Data. Remote Sensing, 4(9), 2661-2693. doi:10.3390/rs4092661

Inspire 1 preflight check procedures 

• Check weather conditions 

• Temperature, Visibility, Likelihood of Precipitation, Wind speed, Wind direction. 

• Check maintenance log book (if applicable) 

• Ensure there are no open entries or outstanding maintenance due. 

• Check that pilot and/or PIC are fit to fly 

• Consider all physical and psychological considerations: are you well rested, clear-minded. Are there any external pressures being applied (client pressures, time pressures)? Confirm no alcohol consumption in past 12 hours, medications that could affect performance. 

Mission area- Go for flight 

• Make note of flight obstructions 

• Clear of all no-fly zones 

• Check for TFR and/or NOTAMS. Check for flight restrictions or restricted airspace for anticipated flight locations. Confirm Class G airspace. Get necessary Tower permissions. Check B4U Fly App. Check Kittyhawk App. 
• Check for wires / cables, Poles, Power lines, Trees, Animals, People / bystanders, Property in the vicinity, Ability to maintain adequate buffer zones between aircraft and personnel, Take into account local topography, ensuring a visible line of sight towards the UAV at all times. Ensure buildings or other obstructions will not affect the telemetry connection. 

• Develop flight plan/Brief all on roles & responsibilities 

• Take into account flight time limit, goal of flight, wind/weather conditions. Discuss the conduct/goals of the flight with observers, co-pilot and spotters. Notify any bystanders or nearby property owners of your intentions (permission). Advise any and all who are involved with the flight of the overall plan, emergency contingencies and location of First Aid kit. 

• Determine take-off, landing site and alternate site 

• Minimize departures and landings over populated areas, select take-off/Landing site that is free of rocks, debris, dirt, tall grass. Deploy area mat if necessary. Ensure site is far enough away from trees, wires, poles, buildings, people, and vehicle traffic. In the event of emergency failsafe return to home, ensure site does not result in overt obstacles to the path of the returning sUAV. Determine alternate landing site in case the original site becomes compromised during flight. 

• Check that required documents are on-site 

• PIC certificate, UAS registration, permission forms signed, etc. 

Aircraft Inspections 

• Inspect UAS for damage 

• Check joints, structural members, check for loose or damaged screws, ties, fasteners, straps. Check for loose or damaged wiring, loose or damaged connections/plugs. Inspect prop mounts and apply slight counter pressure on arms/components to check for loose components. Inspect camera / lens, make sure it is secured and connects are firmly attached. Check that props are smooth and free of damage/defect, check the blade surfaces. Check hub for cracks or wear 

• Controller and Crystal Sky battery charged 
• Drone battery charged, properly installed, secured 
• Lens filter attached 
• SD card installed (rededge and camera) 

• Lens is clean (inspire, tablet) 
• Check red edge 

• Connections 
• Condition and security 
• GPS and light sensor (connected/ secure) 
• Aircraft Flight checklist  

  • Place UAS on clean level ground or landing pad 
  • Propellers securely attached 

  • all arrows aligned 

  • Mount Crystal Sky to controller 
  • Power up controller and Crystal Sky 
  • Place all phones in airplane mode 
  
  
  • Advise all others to turn phones to airplane mode or OFF 

  • Controller Patch antenna down 
  • Power on Inspire 2 
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  • • Ensure the gimbal carries out auto calibration 
    • Check connection between controller and drone 
    • Check status of batteries 

    • Controller, Crystal Sky, Inspire 2 

    • Calibrate compass 

    • Before initial flight of the day & every change of location 

    • Ensure PAF on controller is set to P for GPS flight 
    • Ensure GPS lock is active; check number of satellites 

    • At least 4 bars to lock RTH 

    • Check video signal feed; watch for interference 

    • Set to 5.8 ghz 

    • Check gimbal operation: proper initial orientation and pan/tilt 
    • Check navigation light is functioning properly 
    • Check camera settings 

    • SD card formatted, White balance, frame rate, frame size, focus mode, etc. 

    • Set/Confirm Home Point on map 
    • Check Minimum return height 
    • Set high enough to avoid any objects in area 

    • Check take-off clear 

    • UAS placed in safe launch and land position/ Conduct 360 check of surrounding areas for other ground and air uses. Scan skies for birds. Area clear of by standers / non participants? Ensure all participants are a safe distance from the UAS. 

    • Request Take-Off Clearance from ATC (if applicable) 
    • Note flight take off time 
    • Take off and hover at 10-15 feet 
    • Check all functions are operating properly; listen for any abnormal sounds coming from the UAS that could indicate mechanical problems. 
    • If all OK, proceed with flight
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