DJI Introduces Phantom 4 RTK

The RTK only works with WiFi or Cell Modem radio connection to the drone. Which may not interface with most current GNSS base station we own. DJI wants you to purchase their base station. You also need to use DJI GS Pro to navigate the sUAS. In my opinion, PPK is a better option, which this RTK P4pro does include. I am current testing equipment from a company that is providing a PPK upgrade to any existing?ÿDJI Phantom 4 Pro for $2500, they also sell a new P4Pro v2 w/ PPK for $4000. The PPK result is amazingly accurate.

Posted by: leegreen

The RTK only works with WiFi or Cell Modem radio connection to the drone. Which may not interface with most current GNSS base station we own. DJI wants you to purchase their base station. You also need to use DJI GS Pro to navigate the sUAS. In my opinion, PPK is a better option, which this RTK P4pro does include. I am current testing equipment from a company that is providing a PPK upgrade to any existing?ÿDJI Phantom 4 Pro for $2500, they also sell a new P4Pro v2 w/ PPK for $4000. The PPK result is amazingly accurate.

It is actually in their FAQ, it does not work with any other base station.?ÿ WIFI to network RTK is an option, so those on here who have their own bases bridged to internet connections may have a fighting chance.

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They do not spell out a software workflow though.?ÿ So you take a bunch of pics.?ÿ What goes on from there for us guys that are not familiar with the workflow.?ÿ I assume the pics are rectified and stitched together, then a point cloud is generated and from there it goes into more normal software.?ÿ All I see is a guy running around with a trimble rover in the advertising.

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Their marketing needs some work yet.

At this price point I wouldn't expect it to connect via radio to 3rd party base stations.?ÿ Even if the cellular/wifi connection to external VRS doesn't work well, the cost of bundle with their base station is only $9,000.?ÿ

If you watch some of the videos, you can see they use Pix4D for the processing.?ÿ If you use RTK then the positions are stored directly in the image metadata.?ÿ So then you just import the photos directly in Pix4D for processing.

Now if you go the PPK route, I'm not exactly sure of the workflow, as the positions have to be post-processed then embedded back in the image metadata before you can process with Pix4D.

I'm still very interested in more information.

I have not used Pix4d, only looked at their website.?ÿ It looks like they can process topo data right from drone pics, without the RTK.?ÿ Unless the RTK is just refining the GPS position of the small drone GPS antenna.?ÿ Then the question becomes, if it is the same software and the only difference is the better GPS position, How much better does it make the end product?

I have a phantom 3 pro.?ÿ I think I am going to lay out a few ground targets next month and try their free trial to see how good it is.

The RTK/PPK will be most useful?ÿto reduce the amount of GCP's. With a P4Pro and sufficient (6 or more) GCP's the results are the same as RTK/PPK with just three GCP's. So it reduces your field time. The RTK will help the drone fly a more accurate flight path, but there is potential for radio signal loss. PPK would be less of a problem and more reliable in the end.

The camera sensor size and lack of mechanical shutter will reduce accuracy in the Phantom 3 Pro (not recommended).

Posted by: leegreen

The RTK/PPK will be most useful?ÿto reduce the amount of GCP's. With a P4Pro and sufficient (6 or more) GCP's the results are the same as RTK/PPK with just three GCP's. So it reduces your field time. The RTK will help the drone fly a more accurate flight path, but there is potential for radio signal loss. PPK would be less of a problem and more reliable in the end.

The camera sensor size and lack of mechanical shutter will reduce accuracy in the Phantom 3 Pro (not recommended).

Exactly what we have found with another system. For RTK/PPK you need a minimum of 3 GCP. As few more are helpful if they can be put in without much additional time (in any case you ought to be putting down check points and points to enable you to calibrate the vegetation height correction). The great advantage of PPK is that you can sort problems out afterwards when you can sit down, look at the process data and refine if necessary. If the DJI just stores the RTK position, not the raw data you won't be able to post process it to improve the results.

Any modern gps system, both in air, or ground, should be able to do both post processed, and rtk.

It seems regressive to do rtk, and not post processing.

In my testing of a third party PPK added to a DJI P4Pro v2.0, the precision is very good without any GCP's. The problem is the accuracy is compromised by what I think is datum projection by Pix4d. When I process a project?ÿwith Pix4d with no GCP, the inverse between my checkpoints is very good at ?ñ0.1ft H/V. While the Coordinates are off by 1.4ftN 2.3ftE 3.2ftZ. I believe this is because?ÿPix4d can only create the output coordinates at NAD83 WGS84. While we need NAD83(2011) SPC. Applying 3 GCP's corrects this problem. I am currently working with programmers to have the software make the proper corrections to NAD(2011).

We found problems with Pix4D not being able to correctly use UK datums. Photoscan handles UK transforms much better. GCP's with PPK appear to tighten precisions up by 1-2cm vertically, significantly more if the satellite configurations are not good.

Iƒ??m most interested in the accuracy that can be achieved with no GCPs. I have many projects that donƒ??t need cm accuracy. If I can get 5-10cm accuracy with no GCPs that would be extremely useful for many of my projects. Sub 5cm with fewer GCPs is a bonus.?ÿ

Lee, keep us posted on your work with Pix4D, as Iƒ??m very interested.?ÿ

5-10cm. accuracv should be normally achievable under most circumstances on RTK/PPK only, but you do need some sort of checking to pick up when it goes wrong. In the worst case, as long as your imagery has a few very well defined features, on the flat, then you can always go back afterwards and survey those for use as GCP to recover the job. Using a Sony A6000 we would expect virtually all hard features to come in under 5cm. with no GCP and probably within 3cm with GCP.

I agree. At this point the need for 3 GCP's is for Pix4d to properly translate the output coordinates to the correct protection.?ÿ

At $2500 the addition of PPK to the Phantom?ÿ 4 Pro is a very reasonable add-on.?ÿ

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One other potential useful feature of the P4Pro RTK is using RTK for navigation in addition to image geo-tagging.?ÿ There have been instances where I've been unable to calibrate the internal compass of my P4Pro due to electromagnetic interference.?ÿ From to the press release:

Sitting just beneath the RTK receiver is a redundant GNSS module, installed to maintain flight stability in signal-poor regions such as dense cities. Combining both modules, the Phantom 4 RTK is able to optimize flight safety while ensuring the most precise data is captured for complex surveying, mapping and inspection workflows.

The DJI Matrice 210 RTK already uses RTK for navigation, so I'm hoping the P4Pro RTK will also.?ÿ I have a project located at a major port and was unable to take off at the container terminal due to all of the metal in the area.?ÿ Using RTK for navigation should eliminate that problem.

With the latest software update, PPK results from PPK on a Phantom 4 Pro v.2 now yields?ÿcorrect NAD83(2011) coordinates at ?ñ0.10ft.

I will start a new post with more information on how this process works.

Thank you for your time to write that stuff up.