The active track mission operator is the only object that controls, runs and monitors ActiveTrack Missions. It can be accessed from MissionControl.
An ActiveTrack Mission allows an aircraft to track a moving subject using the vision system and without a GPS tracker on the subject. To use an ActiveTrack mission:
Prepare a mission with the rectangle that best represents the target to track
Start the mission to initiate tracking of the object and begin the state updates (DJIMissionProgressStatus)
At this point, the aircraft will track the target while hovering in place.
Give confirmation that the tracked target is correct with acceptConfirmation and the aircraft will begin flying relative to the target.
If the tracking algorithm looses sufficient confidence in tracking the target, then the aircraft will stop flying relative to the object and either notify the user (through execution state) that the target is lost or it needs another confirmation that the target is correct.
If the mission is paused, the aircraft will hover in place, but continue tracking the target by adjusting gimbal pitch and aircraft yaw.
If mission is resumed, confirmation of tracking rectangle will need to be sent through to start flying relative to target.
stopTracking should also be used to reject tracking confirmation if the camera is tracking the wrong target. After stopping the mission, the mission needs to be recreated with a new rectangle and loaded into the operator.
The main camera is used to track the target, so gimbal cannot be adjusted during an ActiveTrack mission.
During the mission the aircraft can be manually flown with pitch, roll and throttle. Yaw and gimbal are automatically controlled to continue tracking the target.
If the mission is executing, and after confirmation of the tracking rectangle has been sent, the aircraft can be manually controlled horizontally similar to a HOME_LOCK where the home is the tracked target. If aircraft is manually controlled upward, the aircraft will lift and retreat, and if it is controlled downward, it will go down and get closer to the target.
Starts auto sensing. After auto sensing starts, the aircraft will sense humans captured by the camera and return the detected subjects by getAutoSensedSubjects in the updated event. QuickShot requires a special auto sensing mode, therefore, use enableAutoSensingForQuickShot if a QuickShot mission will be performed. It is only supported when isAutoSensingSupported returns true. When the product supports auto sensing, enabling auto sensing is the pre-condition of starting active track.
Starts auto sensing specifically for QuickShot. After auto sensing starts, the aircraft will sense humans captured by the camera and return the detected subjects by getAutoSensedSubjects in the updated event. This interface is specific for QuickShot, therefore, use enableAutoSensing for missions other than QuickShot. It is only supported when isAutoSensingSupported returns true. When the product supports auto sensing, enabling auto sensing is the pre-condition of starting active track.
When the vision system is not sure the tracking rectangle is around the user's desired target, it will need confirmation before starting to fly relative to the target. The vision system will need confirmation when getCurrentState is IDLE. getTargetRect of ActiveTrackTrackingState can be used to show the user the rectangle the vision system is using. If the user agrees the rectangle represents the target they want to track, this method can be called to start flying relative to the target.
Setting a non-zero speed starts the aircraft circling the target. Speed can be set within the range [-5, 5] m/s where a positive speed is a counter-clockwise movement (when viewing from the top). Reverting the speed to 0 m/s ends the circling movement. It can only be called when the getCurrentState is AIRCRAFT_FOLLOWING .
Enables/disable if the aircraft can retreat (fly backwards) when the target comes toward it. When it is disabled, the aircraft will not retreat and instead rotate the gimbal pitch down to track the target as it goes underneath. If the target goes beyond the gimbal's pitch stop, the target will be lost and the mission will stop.
true to enable retreat during ActiveTrack mission.