Field-setup Guideline

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Flight Checklists

   1.2.  Field Setup 
           ❏ Early in the season, distribute at least ten ground control points (GCP) uniformly throughout the field. Four GCPs go in the field corners and rest 
             are distributed inside the field, preferably in the alley ways for better visibility.  Survey the GCPs with either RTK or a DGPS GNSS systems, 
             whichever available. 
             Make sure the GCPs are not not disturbed once surveyed through the entire field season. That is why the choice of placement of the GCPs important to 
             avoid any disturbance.  
             Generally the white color GCPs are easy to spot hence should be preferred.  Some photogrammetry softwares support automatic GCP detection. When 
             available, customized GCPs can also be used.  Here are a few examples of GCPs that have worked well for us:
                 i. Color brick/pavers
                 ii. Metal sheets
                 iii. Plastic discs/frisbees
           ❏ Place the reference calibration panel on a fixed metal frame (or on a flat spot if frame is not available) close to the first mission waypoint at a 
               fixed position (Figure 1.1) 
              Note: The panel can also be utilized as a launchpad. Also, in order to minimize the variations due to varying sun illumination and overcast, maximum 
              aerial shots of calibration panel at regular intervals are recommended. A 20% gradient grayscale calibration panel can be used. This can be achieved either 
              by using multiple calibration targets or by capturing images of a target at every landing and takeoff event during the mission. 
           ❏ Mark the four corners of calibration panel with flags and survey them with RTK or DGPS GNSS system, whichever available.  
              Fixed panel positions make the automatic extraction of individual color panels easier during the post-processing steps.
              Figure 1.1: Example of a grayscale calibration panel attached on a metal frame.