RTK Drone experience

Hey guys,

What do you think of e.g the phantom 4 rtk? Anyone of you using this one?
I‘m in doubt if its worth the money? Does it effect the Result of a 3D Modell as well? Is it improving this or basically the same?

Looking forward to hear from you :+1:t2:

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Good morning @SpatenEvergreen. There are many users of the Phantom 4 RTK on the forum and it is definitely a benefit, but it also depends on your use-case and what kinds of products you are wanting to generate. It is quite expensive and there are many other ways to turn a Phantom 4 Pro into an RTK system, but if you want to buy it and forget it then it is a good package deal. It has been proven not to be the easiest system to work with and unless you get an alternative RC will not work with DroneDeploy, but there are many other softwares that you can use it with. @GregO has had allot of success so maybe he’ll chime in. :wink:

Oh that is already good to know, that it’s so far not working with DD. Big minus tbh…
I know that DJI terra would obviously work with it but it is to expensive for us. Especially when we already have DD.

And what do you mean with other ways? Buy an additional rtk module and build it on the normal p4p? How easy is that?
Thanks for ur quick reply Michael :slight_smile:

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This would be the easiest, but they are still selling the M+. I’m pretty sure you could purchase just the mounting gear and purchase the M2 and antenna separately.

http://www.tuffwing.com/products/Phantom_Reach_PPK_Integration_kit.html

That is the setup I started with and it worked very well in a PPK scenario, but with an RS2 and M2 it is very likely that you could run RTK. Here’s the link for everything you would need if you can get just the Tuffwing mounting.

I then took it one step further and installed the AShot camera trigger capture. It was easy to install and allows you to remove the light sensor and battery pack from the Tuffwing setup as it will also power the M+/M2 unit from the drone. This is ideal for my scenario as I will always do PPK until the use of RTK on a drone is more proven. I absolutely cannot jeopardize a company mission with the opportunity to get bad information from RTK that I cannot fix. Although by using the Emlid system you could always log at the same time for verification.

This is the ultimate comparison to the Phantom RTK at this time and there are a couple of other companies that make a similar build, but the Teodrone is already proven with allot of sample data from the manufacturer. You can install it yourself if you are comfortable with electronics or you can send your drone to them for them to do it.

Here’s the main break and most advantageous part about the Phantom 4 RTK. It tags the photos, not just creating events. With all these other solutions you still have to re-geotag the photos using something like Geosetter. It is very easy, but is an extra step. The downside to the P4RTK tagging the photos is that if you did have weak satellites, a loss of RTK or worse yet a false RTK/float condition you would never know it unless you analyzed the data afterwards and then you would have to re-geotag the photos anyways. This probably is a big deal for small site under 50ac, but the larger the site gets and the further away the drone gets from the base the more likely that this will happen. Not worth $10k to our program when even the full build kit such as Teodrone or Topodrone are half the cost at the end of the day and you get to use your own base station. You can then add another RS2 for a rover to set GCP’s if you want or create a way to use the drone as a rover.

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Thanks for this very useful answer. I have to read it a couple of times more, due to very technical stuff in a foreign language, but I’ll figure out. Thanks again, Michael!

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With M2 you mean the mavic 2 pro / Zoom don’t you?
My thoughts were that I can just use the p4rtk and because of its additional Satellit thing it is capturing much more precise data, so my 3D or even 2D models are more precise in the end.
But I can’t use it for DD due to the fact that with the controller they provide it’s not working yet. Then I read quite a lot in german forums and this even confuses me much more. And I almost don’t get what they are talking about. Probably because they do geotagged measurement professionally for years and we are just starting up.

But thanks and I’ll see what I can figure out :slight_smile:

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The M2 I am referring to is the new Emlid Reach M2. It is the GPS receiver that goes on the drone in combination with the Reach RS2 base/rover receiver. This is actually better GNSS equipment than what is on the P4RTK, just the drone part is not internal and does not automatically geotag the images as they are taken. That’s the second link I posted above, but here is the Reach M2 itself.

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Ok got it. So I actually mount this receiver on my drone itself and connect it via cable.
But I need to get the ground station where it can connects to, correct?
How do I get the data’s tagged to my images then?

I know it looks like I have absolutely no clue about what I’m doing here and it’s kinda right. But I’m learning a lot at the moment :smile:

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Ah you Said it already. Via geosetter! I’ll read into this one now.
You are a real help Michael. Thanks

My problem is that this whole drone rtk whatever topic isn’t that common in Germany yet. So it’s quite hard to find anything useful if your starting with it. There are of course some geeks but yeah. They can’t or don’t want to explain properly…

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My pleasure. I only know about 10 people total that are trying to use the P4RTK and 2 of them are not getting what they want, but I think if they dropped the price a little and sold it with a more open RC then it would be much more popular and we would all be able to help each other much better to come up with practical solutions.

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That’s absolutely right. Had almost the same issue already with using DD at all. Bought the M2Z with the Smart Controller wich is absolutely not smart. So still had to buy the standard etc as well. But let’s see what future brings :smile:

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Good morning. I love P4RTK drone datasets as it comes with a really good RTK and PPK system on board!

You do not get better 3D models, as this is related to your mission planning and photogrammetry software! That’s important to know!

But you can get rid of these annoying GCPs which are time consuming in the field and for placing in the software. Problem is, that you have to know a lot of things about photogrammetry, camera auto-calibration with focal length especially, geoids and geoidundulation to receive accurate results.

But if so, you get a perfect survey system for cheap money! With limits in mission planning due to RC :roll_eyes:

Our Workflow: P4RTK (storing *.obs and *.mrk files, so PPK mode) in combination with governmental service for BaseStation RINEX data; using REDtoolbox for PPK processing and geotagging; Agisoft Metashape, QGIS

:smiley:

I’m glad the p 4 rtk is working for you, but I would hardly call it cheap when it is more than twice the cost of what can be done with complimentary GNSS equipment on a standard Phantom 4 Pro and Mavic 2 Pro.

As for your claims of not having to use ground control points then I would say you are probably not doing the kind of work that many of us are in the land development, infrastructure asbuilting and construction industries or you would have dealt with that data and known that there is no way around using them when integrating with other sources of information and performing analysis.

Hi Michael, may you explain what you mean by this? We’re in surveying and derive point clouds and meshes for BIM (whatever BIM is :wink:) , orthophoto & raster dtm for volume calculations in CAD or GIS software,… also doing monitoring tasks with P4RTK. So what’s your application so I will understand?

It sounds like your projects may be a scenario where the WGS84 data converts directly to a Cartesian (XYZ) projection that does not require any shifts or scale factors. We commonly receive CAD files that have been scaled to match surface distances and the drone data does not transform with these factors into account so it does not import into CAD exactly where it should be. As an example we have an area where the surveyors defined a surface coordinate system that is not truly on state plane so when the drone data comes in it is 300ft south of the CAD. We then have to apply a horizontal scale factor of 1.00012 or something similar to get the data to move up to those coordinates. The other case is if the CAD survey was on completely arbitrary coordinates that are not a 1:1 transformation then we have to align the drone data manually. This is all solved by the use of GCP’s that have been shot in using the GNSS localization of the relation of those XYZ positions directly to the true GNSS values.

Are you able to enter Cartesian coordinates for the base instead of Geodetic? If so, do they have to be on the directly transformed values from the Geodetic? If you can enter a custom XYZ we might be able to get around the problem, but I still don’t think that is going to take care of scale factors for surface coordinates.

RTK/PPK is always related to WGS84 coordinates with elliptical heights.

So I agree, when it comes to local coordinates and scales, the RTK gets irrelevant and GCPs must be used.
Except one case: monitoring tasks with multiple flights over longer time period. For this purposes, we calculate our own 7-parameter transformation formula to reproject the image centres. So in a first step from WGS84 to state plane coordinate system (using standard epsg codes) and then, with our own 7-params, re-projecting this results to local coordinates. But the effort to derive these 7-params is only worth for long time projects.

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Now we are getting on the same page. Would you mind sharing the transformation you are using or PM’ing me? All of our flights are bi-weekly for the duration of the projects and are analyzed in Carlson Precision 3D, AD Civil 3D and Carlson Civil. Our one-off flights are for estimating and sometimes CAD is available and sometimes we only get the contours from the engineer and they have to digitize the plans to get the CAD linework. This is another beast of placement, but that is for another day. We are able to accomplish what we need, but the cost of the P4RTK and the fact that the D-RTK 2 is proprietary and you have to use NTRIP is not a good option for us. We have to many other GNSS efforts in-house including Machine Control that has to all integrate together.

@Hans27, Also, thank you for posting that you are using PPK instead of RTK. I think this is another distinction that people using this drone need to adopt. RTK is somewhat ok for small sites, but as the sites get larger the possibility of false fix or a borderline float/fix signal can ruin a survey. I too always run PPK to certify our work.

We have been using the P4 RTK at Ghilotti Bros. with Propeller. We started using it with their Aeropoints last Spring before DD rolled out their earthwork feature. We really like all the features on the DD platform and are trying to move away from propeller to just using DD but Propeller does earthwork so well. I spoke with one of the DD developers at the last conference and they said they are working on using the bin file data from the p4 RTK drone which is what Propeller is doing now. I hope that’s the case but the other hurdle is being able to use the DD app to plan flights on the RTK drone. It seems like DD is getting closer to using it in a seemless workflow. Michael, your thoughts?

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