Intelli-G and DJI RTK

Although this was never on our development roadmap, given the many people who were screaming for a solution to extract the RTK coordinates from their DJI RTK system, we decided to implement such a solution (for the "screams" see

You can now use Intelli-G to log your RTK coordinates along with other useful information during your photogrammetry missions.

To keep things simple, we made it so you may attach to Intelli-G a microUSB OTG memory stick (like, using the micro USB port that was added with Intelli-G V2. Every time the Shutter function of the DJI A3 FC (flight controller) is triggered, Intelli-G saves the RTK coordinates along with other telemetry information coming from the FC.

Intelli-G connectivity for photogrammetry scenario

- F-Port (Shutter) to ADC4 connection is only necessary for Scenario E - Photogrammetry (geo-tagging) missions, using D-RTK/DJI-GPS

And, since we are engineers, we couldn’t help ourselves not to think of a way to improve the entire process and so, we implemented a way to increase the accuracy of the captured RTK coordinates. Intelli-G doesn’t just take the RTK coordinates as they come from the FC, it calculates new, more precise coordinates, based on the exact timing when the picture was taken. This allows users to run missions at higher speeds while maintaining the best possible accuracy.

Our Beta testers were able to achieve a final precision within 2 cm without using any GCPs (Ground Control Points). If you are not familiar with the different approaches that you may take, we highly recommend that you read the article linked below. Please note that we are NOT associated in any way with pix4d, we just believe this is a good read that applies to any software solution you might be using.

Please note that there are many factors that can affect the overall accuracy of your project and we recommend that, before taking on such a project, you do your own research and study.

A very important feature that we’ve implemented is the possibility of saving the filename of the picture along with its corresponding set of coordinates. This is supported for most of the Sony alpha series cameras. This feature is particularly useful in case you are missing some pictures at the end of the mission (avoids desyncs of records in case of camera misfires). Having to find out which pictures are missing, so you can eliminate the corresponding coordinates from the whole bunch, might be an impossible job when you don’t have the picture name. We are currently working on finding ways to help you in this situation (like saving the coordinates directly on the EXIF properties of the captured images), also when using different camera brands.

What about when not using the RTK, is Intelli-G of any use to me?

First of all, when not using the DJI RTK, the photogrammetry feature offered by Intelli-G is completely free, no special add-on is required in this case.

If the accuracy of the GPS coordinates is important to you then, Intelli-G becomes essential because of the way it calculates the GPS coordinates at the exact moment when the picture was taken (taking into account the latency of the camera in receiving and executing the command to take the photo).

Intelli-G is also essential when using custom cameras that cannot be triggered by the DJI hardware and because it provides the name of the picture (in the case of Sony cameras). The amount of information and the ease with which you can extract the data from Intelli-G is also an important factor.

Our solution is compatible with all DJI flight controllers that have a compatible DJI SDK port: A3, N3, M600 and others. Please note that, in the case of DJI RTK, you should first make sure it is supported by your FC.

The saved files are standard text, each record having the following format: ImageName Latitude Longitude Altitude Yaw Pitch Roll. The separator between fields is space. Yaw Pitch and Roll represent the drone angles at the moment of image acquisition.

Here’s a sample of such a file:
DSC09869.JPG 45.66803450 25.54671240 544.1490 140.18 -0.51 -1.47
DSC09870.JPG 45.66803530 25.54671300 543.7470 139.85 -0.40 -1.46
DSC09871.JPG 45.66803700 25.54671440 543.5600 139.74 -0.43 -1.53
DSC09872.JPG 45.66769720 25.54651520 594.1860 91.44 -13.47 -11.43
DSC09873.JPG 45.66769740 25.54654620 593.9990 89.40 -5.12 -3.06
DSC09874.JPG 45.66770430 25.54660020 593.9480 90.22 -3.88 -0.74
DSC09875.JPG 45.66771100 25.54671750 593.7540 90.11 -2.66 -4.47 

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