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Images skipped in synchronization

Hello,

Sometimes a mission completes with say 100 images, but only 99 are then synchronized back to the app and my smartphone. I only found out when I went to clean up the drone sd card and there was one or two extra images. What is the reason to leave them behind?

Using Pix4D Capture 2.0.8 on Android 4.1.2 with Phantom 2 Vision+

Thank you

I have realized that this can be an indication of wrong geotagging. When I look at the pictures on the last flight line, the first of them does not belong there, but to the previous flight line. The other pictures seem to have the correct geotagging, but the image count on the last flight line is ahead by one. Once the end of the flight line is reached, the last picture is taken by the drone, but ignored in the .p4d file.

I am not sure what the cause is. Maybe bad wifi signal, but I was flying in open space. Maybe the wind was too strong, thus delaying the drone manoeuvres and causing a mismatch between timings and positions.

Only solution I see is to fly again, with extra space at the end of each flight line, so as to be able to discard mishaps.

Any suggestions appreciated. Thanks.

Hi Daniele,

Have you tried to create a project from scratch and import the images saved on device? Unlike those on the drone’s SD card, they have accurate geotags. It could make a difference compared to processing from the generated .p4d file.

If this does not change anything to the bad location of some images, there might have been some delays in the communication between the drone and the app. Did you make additional attempts more recently?

Regards,

Hello,

Thank you for your reply. Yes, I have tried a few more times. I randomly get miscommunications between drone and app, or maybe it’s delays in flushing data. The effect is a picture is taken by the drone and saved on the SD card, but its geotag info is assigned to the next picture. As a consequence all the subsequent pictures are out of sync. I was flying missions of 100+ images.

The only workarounds I found was to fly again, or to manually correct the geotagging post mission.

Thank you

I am glad to read that you found some successful workaround at least. Thank you for sharing your experience!

Actually we suggest that you discard the images saved on the drone’s SD card.

It is important to process the images using the .p4d file since it contains the accurate geolocation of the images. P2V(+) has an accurate GPS however, for some reason, when passing the geolocation to the EXIF of the images in the SD card some decimals are removed. This truncation problem creates Lat./Long. coordinates that are the same for several images. Also note the P2V(+) does not measure altitude because the drone does not have an altimeter.

Our application writes accurate image geolocation using the device’s GPS in the .p4d file, and we do not remove any decimals. These accurate coordinates are also imported to the EXIF of the images when they are copied to the device. If this is not achieved on the field, it is still possible to synchronize the mission later on: https://support.pix4d.com/hc/en-us/articles/204716225

If you were able to access the .p4d file and process from it, then we expect a successful computation with reliable geotags.

Regards,