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Linear mission non optimal with P4A

Hi,

i did a linear mission using a new P4 advanced but the resulting overlap was not optimal. I used 80/80 overlap at 60m which resulted in 6m/s speed. Map Pilot version 3.1.5.

I thought that distance-triggered method was more accurate than time-triggered. The P4 advanced supports distance-triggered method right?

As you can see from the attachment the photos have large gaps or small gaps between them and the overlap is not optimal.

Some older linear missions i did with P4 (time-triggered) was much better than this.

If you have any suggestions or tips i would like to hear them!

George

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Since the camera is triggering that it looks like it could be SD card write speed related. You could try a slower setting like 3 seconds/image. Also, benchmark you SD card to make sure it can keep up. 

If you are using terrain awareness we have to set the triggering method for each segment which can cause gaps at terrain inflection points while the triggering is reset. This is just how the DJI camera works. 

I can confirm that the distance triggering is working as it should for other users. 

Zane
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Time triggered and distance triggered is basically the same accuracy when it comes to reconstructing the scene. The P4A is distance triggered. 

Since the time and distance triggering is all handled within the camera there isn't much we can do to change the spacing.  

It depends where you are getting the dot locations from here. Are they from the log file or the exif tags? The filenames get populated by a message from the aircraft (that is how the log file knows the name of the file the camera creates). These messages come in anywhere from .5-2 seconds after the image is actually taken.

 

Zane 0 votes
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Thanks Zane,

the locations are from EXIF tags. I will do some more testing to check the P4A.

One more question about connectionless mode, if the RC loses the signal entirely will the drone continue the mission or Return to Home?

George 0 votes
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The whole point of connectionless mode is that it will keep flying even in the RC loses connection. The aircraft will continue flying until the battery runs out and returns home or the full flight is completed. 

Zane 0 votes
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Thanks Zane,

I updated to the latest 4.0.6 version and did two more tests with linear flights.

The results was not satisfactory. Again there was gaps between the photos (see attachments).

My previous tests with P4 (time-triggered) was much better and did not suffer from this problem. Is it possible to select the method (time vs distance triggered) on the P4Pro/Adv?

George 0 votes
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The SD card is a 32GB Sandisk Extreme Pro which I have tested and it writes at speeds 80-90 mb/s so I don't think this is the issue. The terrain awareness is much more reasonable explanation since my area has a lot of relief and I always use terrain awareness but from the https://app.airdata.com/share/rKscxf/GENERALNotifications you can see that this is not the case. After waypoint 4 there is a row of photos and the gap is between S and T event before Waypoint 5.

I will try the 3 sec/image setting and also another SD card and report back. I don't know if it is difficult to code but It would be nice if the user could select the method (time vs distance triggering) since the gaps in the photos lead to holes and bad results.

George 0 votes
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Hi,

here are today's 4 conectionless linear flights. All of them have problems with small to big gaps.

https://app.airdata.com/share/vGwAyA

https://app.airdata.com/share/VGOGcb

https://app.airdata.com/share/JfgeVy

https://app.airdata.com/share/wbCEnh

Please can you help me troubleshoot why this is happening?

I am running P4 Advanced with latest firmware and ipad mini 4 with ios 12.3.1 and latest Map Pilot v 4.0.6

With active connection there is no problem.

SD cards tested are Sandisk Extreme 16GB and Sandisk Extreme Pro 32GB.

George 0 votes
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I can verify that this is not happening with other users of your aircraft. The triggering is done by the aircraft. Start slowing things down to rule out camera writing issues. Try flat flight to rule out Terrain Aware issues. 

Sharing the AirData logs doesn't help since it is only reporting where the aircraft was when the camera tells the app it took a pictures. That is not where it was when the picture is taken. Sometimes these messages never arrive, sometimes they are late but they are never going to be right on. You need to debug this using the locations from the EXIF. 

There are certainly tradeoffs in going from Active Connect to Connectionless. 

Zane 0 votes
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Sorry for the delayed response, I was a little busy.

I did a linear flight test without terrain awareness and the results are much better.

The results with terrain on based on EXIF positions are below and of course not acceptable (maybe the second pic is just ok).

I don't know if it is my P4A or some other problem but for now I have to use only active connection. Pity because I would really like to have a consistent linear flight with terrain awareness.

On the other hand I am really happy with the results of the new camera and I must not complain..

George 0 votes
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The distance triggering gets reset at every waypoint so when terrain awareness is used and the extra waypoints are visited it will cause gaps. 

There is a workaround that forces the app to use Active Connect mode even though it is a Linear mission but I will have to look it up. It was actually a bug that I don't think has been fixed yet. 

Zane 0 votes
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Zane,

maybe you have looked up for the "bug" that forces the app to use active connect mode in linear flights?

I am interested to test if it works better for me.

Thanks!

George 0 votes
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The bug that allowed you to select Active Connect model when doing linear mapping has been fixed. We will look in to adding an override technique in the next release. 

Zane 0 votes
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Hi Zane,

did you add the Active Connection mode on the Linear flights?

I need an active connection on small linear flights of about 500m length which is ok for active connection.

George 0 votes
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Hi Zane,

I would like to report that the linear mission with active connection works like a charm in Map Pilot 4.1.7

I did 3 missions, same place, different altitude 40m,50m,60m and all went very very well with linear-active connection. No missing images at all.

The only glitch was that although i had saved the missions with active connection, when I loaded them it reverted to connectionless mode and had to unlock the mission and select active connect.

Also the camera control was very good. With previous versions I was having problems with camera not keeping the settings like shutter priority or manual control. This time the settings remained like it was set and had no problems at all.

Thanks guys!

 

George 0 votes
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