[iOS] Pix4Dcapture with DJI drones

@Pix4D Support

Thank you for the update. This means a lot to all the operators out there, especially the commercial operators like myself. I have sent you the log files as requested. I can confirm all the firmware is up to date.

There are a couple of things I’d like to clear up. So, you are saying importing the geotagged images into Pix4Dmapper will give the same accuracy if you sync with the Capture app first and use the .p4d file? If that is the case, then for me, it makes better use of my time to process the data at the office then to wait on site for the app to sync.

I read in a previous post that issues with syncing after the mission might be related to the number of images on the SD card of the drone. In my case yesterday I flew three flights. The first two synced (although took a fair bit of time) and the third failed. Do you still recommend downloading and clearing the images off the SD card after each flight? 

The last thing I would like to discuss is the accuracy. Yesterday’s flight was set with 85% overlap, in fast mode (but lowest possible speed) and an altitude of 30 meters. The images were processed through Pix4Dmapper. The geolocation variance was +/- 3 meters. I have a fixed wing drone that gets it down to +/- 1 (or less). Ground points are not used in both cases. Is there anyway to get the data a little more accurate without having to use ground points?

 

Your suggestions would be much appreciated.

Regards

 

Hi Paul,

Thank you for prompt reply and your comments.
I have forwarded your log files to our developers who will have a look.

1. In terms of accuracy, processing the images by creating a project from scratch or using the generated .p4d file will not make any difference. The .p4d file contains a process area that will make step 1 faster however.

2. There are many reasons that explain the fail in synchronizing, and the image numbering might indeed be one of them. We would suggest to always remove the images from the drone’s SD card after you flew a mission and transferred the images to your computer. It is always better to avoid gaps in the image numbering, e.g. having on the SD card images DJI_001 to DJI_050 and then DJI_80 to 200.

3. The absolute accuracy of the outputs should be closed to 1-2 times the image pixel size (GSD) horizontally (X, Y coordinates) and 2-3 times the image pixel size (GSD) vertically (Z coordinate) using GCPs and assuming a measurement error of 20 cm. Without GCPs, your model will be accurately located with an error of 5 m and 10 m respectively using image geotags recorded by basic GPS. The geolocation variance of 3 meters you achieved is reasonable. It depends on the drone’s GPS and on the flight condition (weather, loss of connection…).

Note that DJI measures the absolute elevation above sea level using EGM 96 as the reference. They used to record the elevation above ground level but this is no longer the case. However the vertical coordinate is still not fully reliable. Indeed, we made testing in our office here and we found that the vertical coordinate is off by several meters that can reach an error of 100 meters. Some users noticed the same. Therefore our developers suspect something wrong in the DJI EXIF regarding the vertical coordinates.

As a consequence, we always recommend to process with ground control points (GCPs) in order to fix these uncertainties.
About using GCPs: https://support.pix4d.com/hc/en-us/articles/202558699

Hope this answers your questions :).
I will keep you updated about the log files.

Regards,

@Pix4D Support

I am attempting to use the Capture app to conduct both 2-D and 3-D grid missions.  I am however having difficulty flying the missions below 30m.  I get the warning that the height is low and to watch out for objects and be ready to take control, but the mission never successfully loads, and I am left without the green check, when I proceed in the menu.  However, when I then cancel out of the menu and then change the altitude to 30m +, using the exact same grid and other settings, when I proceed through the menu the mission loads and I am able to launch my DJI Phantom 3 Advanced.  Can you please help me address this problem?  Is there a built in safety feature somewhere that doesn’t allow me to proceed below 30m?  Thanks.

@Ian Comeau

There isn’t any limitation in Capture app that is preventing to fly missions below 30m of altitude. We’re aware of a limitation in DJI SDK (what allows the communication between the app and the drone’s firmware) that is not allowing to upload missions where waypoints are too close to each other. For instance, this can happen when you create low altitude mission with high overlap.

Which was the dimension of the grid, overlap and altitude of the mission that you were not able to fly?

Also, what you can try do is (as a temporary solution):

  • Slightly adjust the grid to increase the distance between lines

  • Slightly reduce the overlap

I hope this helps,

Regards

@ Mattia Cugini

Thank you for the information.  I reduced the overlap in Settings and was able to complete the mission successfully.  Appreciate the response!

 

Hi guys, I’m doing my final course assignment in photogrammetry with UAV, and my doubt is: can we consider the overlap that we set in the app, the same for frontal and side overlaps?

I found this in the pix4d Capture App Manual: “The side overlap is computed such that the side distance between two images is twice the front distance meaning the distance between two images on the same flight line. The side overlap is adjusted with the number of lines so that it is close to the defined overlap value.”

But I’m still not sure about it.

Thanks.

Hi Alessandro,

The overlap value that can be defined in the app corresponds to the frontal one. Then we adjust the number of lines of the grid so that the side overlap is close to the value but it will be slightly less. 75% frontal and a side overlap of 60% are at least recommended in most cases. If you want to achieve a side overlap of 80%, we would suggest that you set the overlap in the app to 90-95%.

For more information about image acquisition: https://support.pix4d.com/hc/en-us/articles/202557459

Regards,

Thank you so much for the response!

We would like for the Capture App to be able to import a KML polygon for the project boundaries. Is that planned in the near future?

Thanks, Raymond

Hi Raymond,

This has been requested by several users. Thank you for sharing your feedback with us.

Developing a stable app is always a trade-off between:

  • Implementation of the new features based on users’ feedback.
  • Technical and coding limitations including the SDK of the drone provided by the manufacturer.
  • Testing and bug fixes.
  • Integration of new drones and cameras.

Our Product Team tries to consider as many suggestions as possible given the different priorities in our pipeline. So far we are not able to provide any time frame.

Rest assured that your feedback will be taken into consideration.

Regards,

Hello, is it possible to resume mission when the battery is getting low and i need to swap battery and i fly a bigger double grid with high overlap (iOS version) ? and if it is, can you tell me the method?

Kind regards
Miroslav

 

I suggest to unpin this thread, since it start with announcing the new Capture version 1.3.2, which seems to be outdated.

Or am I making a fuss?

@Pavol: This feature is not implemented yet. You can have it on Android though. Please find more information here:
https://support.pix4d.com/hc/en-us/articles/211826243

@Reto: We will update soon the post with the latest iOS version when it is publicly released. So far the status is beta for 1.4.0 so not all the users have access.

Hello, yesterday I  used  pix4dcapture  for route planning.I used DJI 3pro UAV to fly two times in the same route, and taken to the two groups of photos. But it is found that the latitude and longitude of the two groups matches very well, but the height  error is very large. Two flight parameters, routes are exactly the same, i do not know how to solve…HELP PLEASE,thank you!!

@xu tong

I think there are two ways to solve your problem:

1.Add GCPs to your project
2.Manually correct the altitude with ‘Image Properties Editor’

 

 

Hello I'm using Pix4D Capture with DJI Phantom 4, after seeing the launch of Parrot DISCO interested in knowing, Pix4D Capture is avaiable also for the Parrot DISCO

 

Hi Patricio,

Thank you for you interest in our product. It is in the pipeline to add the Parrot Disco to our list of drones supported by Pix4Dcapture. However, the developers have not started to work on it yet.

Unfortunately, we are not able to give a precise time frame for the support of Parrot Disco at the moment.

Regards,

ok, this is a new one on the Inspire 1 with the X5Raw camera.  Previous to the Sept 20th, 2016 release, images were crisp and clear.  First time with new app, images are consistently blurry.  I checked settings and flew three missions, all similar blur levels.  DJI Go app is fine.  Anyone else having this issue?

Hi Jason,

It seems like the images are out of focus.
To solve it, switching the camera into MF and making sure the focus is set to infinite in the DJI GO app should help.
Let us know if the issue persists.

Regards,

I posted this question to another part of the forum as well, but this seems like a better place to ask.

I just downloaded this app for work. On Friday, I flew a test flight with our DJI Inspire 1, but now I can’t find the images that it supposedly took. We didn’t have time to sync in the field because of weather, so I figured I’d do it at the office. At the office, I connected my camera’s memory card to my laptop and found nothing. Then I put the card back into the camera, powered the drone and remote control on, turned the app on and looked at “Mission Manager.” Nothing.

I have a few ideas of why this might have happened, but I don’t know which one is correct, if any. First, we were unable to log in to the app because we didn’t have wifi where we were flying (we use an ipad that connects to the RC via USB). Do you need wifi to collect & save images, or do you need to be logged in? Also, at the end of the flight, it started raining, so I quickly turned everything off and brought it inside to dry off. Did I turn it off too soon or something? I thought the images would save to the app so that I could upload them any time, but that doesn’t seem to have been the case.

I don’t care if I can’t retrieve these particular images–this was just a test flight. But for future flights, I’d really, really like to know what the problem was so I don’t screw up again. I’ve read the manual, but I’m still not at all clear. I’d really, really appreciate some assistance!

 

OK, correction: now under “Mission Manager,” the mission shows up but says “error” and has no images associated with it. What can I do to prevent this next time?