Recorded images are not parallel to the direction of flight (P4P)

Hello there,
the last days i was testing map pilot pro app for use at mapping missions.
Carrying out a grid missions or linear mission the drone should fly straight along the flight lines. So far so good.
The camera is looking down (nadir) but orientation is inclined in relation to flight direction (see attached picture; red bad; should be like the green example).
I noticed this behaviour through live stream on the tablet. My first assumption was that the drone is not flying straight ahead the
flight line. But i could convince myself that the drone is flying straight ahead.
So i assume that the cameras (gimbal?) vertical axis is not oriented in flying direction.

What happened and what can i do to avoid this?
I am working with a phantom 4 pro and ipad (newest firmware and software)
Thanks in advance.
Thomas

Maier Thomas January 17, 2018 22:47

Official comment

We have heard this feedback a few times and have verified that we are commanding the gimbal to 90 degrees down and zero degrees in pan and roll. You can see that these are the numbers if you look through your log file.

The issue here is the presence of a head or tail wind which makes the aircraft rotate a bit to handle it. It seems DJI doesn't account for that in the pointing of the gimbal although they probably should.

The way to avoid this is to fly during periods of minimal (or no) wind. We will look into correcting for this in a future release. We want it to be perpendicular too.

Zane January 18, 2018 17:01

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7 comments

Hi Zane,

Thanks for your reply.

I am wondering because i made my latest flight nearly zero wind conditions even for testing about this. And the result was as described above.

Its a little bit tricky now because it is often impossible to wait for zero conditions to carry out a job for a client.

If in the result the front and side overlap of the images is still as planned upfront it does not matter.

But this seems to be difficult to estimate.

Ok. let´s see what happens in a future release of Map Pilot.

Maybe there is also an improvement on DJI´s side.

best regards

Thomas

Maier Thomas January 19, 2018 12:24 0 votes

Zane, is DJI receptive at all to fixing stuff like this in the SDK? I would think devs would be on their own for the most part.

Dave Pitman January 19, 2018 16:32 0 votes

This is sort of how their gimbals work. Due to the limited yaw of the 3 axis gimbal system the gimbal angles are commanded with respect to the aircraft body. This is the way most manufacturers do it. Until you get up to the super expensive military ones that operate with a slip ring rotation range will be limited by the flat flex cable length.

Zane January 23, 2018 17:31 0 votes

Makes sense. The phantoms can only correct a little yaw. I suspect you'd have to calculate the difference of the heading vs the track and command the yaw by an equal amount. May work on the inspire if many are using those.

Dave Pitman January 24, 2018 02:06 0 votes

Have any of the updates over the past year addressed this issue? If not, is there a recommended workaround? We encounter this issue regularly when flying railroad corridors. It's not a deal breaker but you do have to take it into account since it can change your anticipated overlap and cause processing issues on the back end. This is a great app, regardless of this issue (sounds like it's more of a DJI SDK limitation anyhow). Thanks!

Nick Elliott March 24, 2019 19:26 0 votes

We have messed around with it but at this point manually adjusting the cameras roll or the yaw of the aircraft manually with the left stick is still the best way to handle this.

Zane March 25, 2019 01:08 0 votes