Should I try and correct for Litchi GPS errors....or just re fly mission?

[goblues38us]

I flew my first "disconnected" mission. I basically did on big oval, with me in the middle and lost connection on the 2 ends. Planned on mission hub @ flylitchi

When I reviewed the video, i noticed my POIs where off by 10-30 feet in most cases.

Example. I had a POI set on the middle of a "round-a-bout", with the camera set to focus on the POI, but as the P3S flew by, the camera was clearly tracking a point on the ground 30 feet away.

Is the just something that will change from flight to flight based on current conditions, or is it a problem with the GPS coordinates on the mission hub (google).

There are a lot of elevation changes where I am fliying. some points are75 below me, some 25 feet above me (AGL). Bird is set to fly a constant 200 feet above take off point.

 

[Richard R]

I flew my first "disconnected" mission. I basically did on big oval, with me in the middle and lost connection on the 2 ends. Planned on mission hub @ flylitchi

When I reviewed the video, i noticed my POIs where off by 10-30 feet in most cases.

Example. I had a POI set on the middle of a "round-a-bout", with the camera set to focus on the POI, but as the P3S flew by, the camera was clearly tracking a point on the ground 30 feet away.

Is the just something that will change from flight to flight based on current conditions, or is it a problem with the GPS coordinates on the mission hub (google).

There are a lot of elevation changes where I am fliying. some points are75 below me, some 25 feet above me (AGL). Bird is set to fly a constant 200 feet above take off point.

That kind of 'error' is pretty typical considering both the inaccuracies in the positioning in Mission hub and in GPS position in the bird itself. Basically, you are RSSing the two errors and both the amount of error and the direction can change everytime you fly a mission. The only way to correct it is to have the original raw GPS data and a ground station so that you can use differential processing to reduce the error. I've used that approach before on several airborne sensor programs, but the equipment cost way more than our birds!

 

[smiller]

There are a lot of elevation changes where I am fliying. some points are75 below me, some 25 feet above me (AGL). Bird is set to fly a constant 200 feet above take off point.

Remember that in Litchi the POI altitude setting is based on the takeoff point (as is every other altitude reference), not the ground level of the POI. If ground level at the POI is different than the takeoff point you need to account for that in setting POI altitude aiming point or your results may be different than you expect. This has caught me more than once.

 

[goblues38us]

so when my POI is recorded and it says it is "20 feet lower then 1st waypoint", it records my waypoint @ +20 feet

 

[smiller]

I'm saying that if, for instance, your POI ground level is at 200 feet and your takeoff altitude is 100 feet and you set the POI aiming point to 30 feet high, the gimbal will be pointed below the POI (which could end up looking like nearby ground, as in your example.)

 

[bsartist]

I'm saying that if, for instance, your POI ground level is at 200 feet and your takeoff altitude is 100 feet and you set the POI aiming point to 30 feet high, the gimbal will be pointed below the POI (which could end up looking like nearby ground, as in your example.)

Yeah this has happened to me. The OP needs to see if it's yaw error or pitch error. Is the camera looking above or below the POI (pitch error which may be caused by incorrect POI elevation as you describe). Or left or right of the POI (yaw error which I guess could be GPS induced.)