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How Curved Litchi Missions and DJI Fly Waypoint Missions Differ

DJ Wes

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Most people who have used both Litchi and DJI Fly waypoint missions know that the flight paths differ. If the same set of waypoints are used in both applications, in DJI Fly, the flight path goes through the waypoints while in Litchi, they do not.

Capture.PNG

Upon initial inspection, it appears that Litchi is using a B-Spline while DJI is using a composite Bezier curve. However, that is not the case. I know that many will not care. If you do want to know but don’t care about the details and just want the answer, Litchi is using straight lines with quadratic B-Splines (or quadratic Bezier curves) at the interior waypoints while DJI is using a Centripetal Catmull-Rom Spline.

If you are curious and want to know exactly how both Litchi and DJI are creating their flight paths, I have created a document that explains in more detail.

 
Thanks. That’s very interesting.
 
Most people who have used both Litchi and DJI Fly waypoint missions know that the flight paths differ. If the same set of waypoints are used in both applications, in DJI Fly, the flight path goes through the waypoints while in Litchi, they do not.

View attachment 172496

Upon initial inspection, it appears that Litchi is using a B-Spline while DJI is using a composite Bezier curve. However, that is not the case. I know that many will not care. If you do want to know but don’t care about the details and just want the answer, Litchi is using straight lines with quadratic B-Splines (or quadratic Bezier curves) at the interior waypoints while DJI is using a Centripetal Catmull-Rom Spline.

If you are curious and want to know exactly how both Litchi and DJI are creating their flight paths, I have created a document that explains in more detail.

Have not used either one, however, last night I had decided to look into DJI waypoints for my M3. Which of the above two photos is the Fly Waypoints?
 
Thanks Wes.
 
I might be mistaken but if I interpret their wording correctly DJI offers turning before waypoints, too, similar to Litchi.

From the Cloud API documentation:
"Note: The setting method of "Turns before waypoint. Flies through." mode in DJI Pilot2/FlightHub 2 is
1)Set the "wpml:waypointTurnMode" to "toPointAndPassWithContinuityCurvature".
2)Set the "wpml:useStraightLine" to 1."
 
I might be mistaken but if I interpret their wording correctly DJI offers turning before waypoints, too, similar to Litchi.

From the Cloud API documentation:
"Note: The setting method of "Turns before waypoint. Flies through." mode in DJI Pilot2/FlightHub 2 is
1)Set the "wpml:waypointTurnMode" to "toPointAndPassWithContinuityCurvature".
2)Set the "wpml:useStraightLine" to 1."
Yes. The WPML language supports a number of "Waypoint Turn Modes". The setting that is closest to Litchi is "Coordinated Turn". By default, DJI Fly uses "ToPointAndPassWithContinuityCurvature" which is the last displayed example in the image below. Here is a diagram of the five modes:
Capture.PNG
While all of these are supported in the WPML language, all may not be supported in DJI Fly's implementation. DJI Fly does not provide a way to choose between them. It is unclear how DJI Fly would handle "CoordinatedTurns" if a mission with that value was uploaded to the drone.
 
Yes. The WPML language supports a number of "Waypoint Turn Modes". The setting that is closest to Litchi is "Coordinated Turn". By default, DJI Fly uses "ToPointAndPassWithContinuityCurvature" which is the last displayed example in the image below. Here is a diagram of the five modes:
View attachment 175056
While all of these are supported in the WPML language, all may not be supported in DJI Fly's implementation. DJI Fly does not provide a way to choose between them. It is unclear how DJI Fly would handle "CoordinatedTurns" if a mission with that value was uploaded to the drone.
Thank you, very informative. Where is the diagram from?
 
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