GCP vs RTK vs Mobile GCP's

So, trying to figure our which direction to go here are my choices:

  1. Have permanent monuments installed at sites utilizing a professional surveyor at around $125/hour on each of the sites that I work on.

  2. Purchase a custom RTK enabled drone and not use GCPs, unless they are already installed on the site.

  3. Purchase the reusable, mobile AeroPoints at https://www.propelleraero.com/aeropoints for $6,000+ shipping.

  4. Any combination of the above.

I would prefer either the standalone RTK unit for around $11,000 or the AeroPoints; however, I have not been able to test either option in person. ANy thoughts or experiences out there?

Here is the RTK unit I am looking at:

M600 - $4599

X5 Camera - $1799

Bracket - $169

RTK Kit - $4599

RTK Mounting Bracket - $69

What type of accuracy are you trying to achieve?

Looking for as close to survey absolute accuracy as possible, give or take 3 cm probably works. Reading this, http://forum.dji.com/thread-50082-1-1.html, it appears the M600 config above may not work as it is still a relative accuracy and may still need base station assistance for corrections. Ultimately trying to do initial engineering design work, without using a surveyor (or at least reducing their role).

You may consider renting an RTK unit. Most survey equipment resellers will offer training to get you up & running. If your work doesn’t require being stamped by a PLS or RLS, this may be a viable option for you. Rental units where I’m at are in the neighborhood of $2-300 per day.

The M600 RTK doesn’t yet use RTK to tag the images. Maps will still come out the same as if RTK wasn’t used. DJI is supposed to change this in the near future with a firmware update

So it may be a better option for me to go with the AeroPoints and just forward the mobile GCP data they output to you guys in a CVS format, or at least until the GCP interface is updated.

Yeah. And GCP workflow is being worked on right now.
M600 should work with RTK tagged images in the near future as well.

I have a conference call at lunch with the AeroPoint folks today. I will update the group with any information they provide.

So using their AeroPoints I can do the following, per my call with them and assuming they were accurate in the information they provided:

  1. Place the points and connect to their correction network. Their network has ~75% coverage within my current project areas. They need to sit and “think” for 30-minutes; however, you can fly the area during this time.

  2. Tie into onsite base stations or rent a base station and let it “think” for 30 minutes.

  3. Place them on top of a known location, like a single known established GCP. This is likely going to be done with me since I usually have access to at least 1-2 known state plane located points. If it ties into the corrections network, then that just adds more. This is also a 30 minute deal.

  4. Place them out around a site without correction network access, no known locations or base stations. You have to let them sit for ~5 hours to make the desired corrections; however, you can fly the area during this time. This can have a absolute (or global) deviation of 8 inches.

They did state that all local, relative, deviations are at 1 cm or less based on any of the above mentioned methods. That works great for one time projects; however, many of mine will be recurring so I would like as much absolute accuracy as possible.

Have a look here for an alternate to that work flow which costs you money and limits your number of GCP


Took a look at the site and the things are still in kickstarter per the email that they sent back to me. I have attached their email below:

Hi there, currently we have two surveying products on offer.

The OBS is a system that will allow your to place as many ground control points as you want with no network costs associated and a very small, easy to use form factor.

This system is a Kickstarter campaign in order to gage interest in the market and raise funds to take it the professional level that we know it can be.

The cost is in the Kickstarter at $3900 US

_The second product is Stryder which can do surveying without ground control and will be available first quarter next year for approximately 30,000 USD _

IF you have any questions regarding the above products or how to use ground control to make your existing data capture accurate please feel free to ask.

I would probably look at the ebee rtk unit for that price point. My aeropoints shoudl be delivered next week with the P4Pro, so I will have some new toys to play with.

Ebee RTK is a fixed wing plane which will over fly roads and property not involved in your operation. In Canada that’s a big no no.

RTK is also no good for drone survey, moving your base, losing your fix, having to fly with a laptop, no manual controls. I could go on and on. Ebee RTK is also not 30k :slight_smile:

We have to change the name from RTK on ours to “geo” becuase we were never RTK people just associate RTK with accuarcy but in actual fact PPK is more accurate and reliable than RTK in any situation. Stryder is PPK.

Also landing and launching areas are large, skid landing, no video and photos inspection and service on another continent.

It’s all about choice.

BTW Stryder is not a kickstarter.

Good points, as overlap area and access can be a big no-no here as well :slight_smile: I think my response was misleading, in that I would not be interested in the ebee rtk as I am a copter kinda guy.

I am following you via your newsletter sign-up and am excited to see what you guys have over time. Also, some more information about your STRYDER copter on the website would be good. I thought it was part of the Kickstarter and just glanced over it. Knowing that it is not, I would be interested in more details :slight_smile:

Good Luck

I just purchased this full kit in Dec 2016. M600, X5, D-RTK with Base Station.

I enjoy the compass failure redundancy, flight accuracy, and anti-magnetic interference capability.

I am just getting into mapping.

How can I use the DJI D-RTK Kit to my advantage?

Can I place the D-RTK Base Station on a known survey pin and create Surveyor accurate maps for my clients or valuable property boundaries?

Can I place visible Ground Control Points at measured locations for reference?

This is a great discussion, and one of the most important as it relates to accuracy in survey.

I survey mine sites and have verified GCPs from previous surveys. Now to match reoccuring surveys:

  1. Do I tag and geoposition those GCPs in before or during my upload to DD so that my DD model, point cloud, and ortho are accurate several CM? …or …
  2. Do I process and upload in DD as normal, and then export to GIS software where exported data is rectified and corrected to GCPs?

RTK is a technique of using real time differential GPS (DGPS) corrections to provide precise absolute positioning.

The DJI RTK soution is NOT a survey grade solution - meaning that it is not designed to be mounted to a survey tripod and precisely positioned over a known benchmark. There is no facility to enter the base station coordinates in the software and then use that known position to compute the derived position of the rover (drone) in real time.

You see - this is the danger when companies such as DroneDeploy (sorry guys but lets tell it how it is) try to make surveyors out of people that have no formal training in survey and are not qualified surveyors. By offering the so called ease and capability of ‘making maps’ they have now created a situation where some knowledge, rather than full knowledge, could present inaccuracies in delivered data which could result in incredible financial losses on the part of the receiver of such inaccurate data.

Surveyors are trained and qualified in their profession. They practice their profession with all of the expected checks and balances in place after going through rigourous assessment and training.

What I am saying here is: be mindful of what you are getting into. If you dont really understand, leave it to the professionals please. If you cannot prove the accuracy of your data with a test point and the associated computations, and understand why the erros are what they are, call a qualified surveypr to help you. Its all about knowing your limitations.

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I agree that understanding what you are doing and what your data means/can be used for. I am not sure that DroneDeploy is trying to make anybody a surveyor anymore then Carlson, Trimble or other equipment companies are. I take DroneDeploy as a software that provides data management and data assembly solutions.

Each user is responsible for what they do with, and what they portray, the data and information that DroneDeploy provides. You will not be afforded the luxury of blaming DroneDeploy, anymore then you could blame Trimble, for any broken promises/lies given to your clients. In addition though, we all make educated/calculated decisions on the use of various technologies that we do not fully understand on a daily basis (cell phones, calculators, cars, computer programs, etc). We do this because we have seen reproducible results and outcomes from the technology. This is what allows me to use the data from DroneDeploy, reproducible, verifiable, results.

In terms of surveyors, remember that the title is meaningless. Being a registered and licensed engineer, I have seen college educated surveyors not be able to function if their equipment stopped and I have seen 60 year old’s who are surveyors via 40+ years of experience calculate means and bounds in their heads with made up math. They both called themselves surveyors. I did internships while in engineering school with some major surveying companies. My work was almost exclusively in the field, and never once worked with a licensed professional land surveyor the entire time in the field (they did show up to talk to clients/contractors and check up on us (unless we were miles in a wetland :). These field guys I worked with were staking out foundations for multi-story buildings, highway on ramps, subdivisions, legal boundaries and more.

With all that said, be aware that certain states have specific laws about what constitutes a survey that must be conducted by a licensed professional (usually I am good due to the ability to conduct engineering surveys and studies as a PE). I would consult legal council in your areas, be very specific in your deliverables language and be upfront with your clients about what you are providing them.

Hi! Yes I totally agree with you. I am not in the US…my comments were more aimed at some of the rediculous cmments I see on the DD forum lately.

Its very clear that this technology is sometimes in the wrong hands. Some of us are making a decent living from UAV surveys - but it seems that anybody thinks they can do the same by investing $1000.00 and downloading DD. I have a fleet of 4 fixed wing and 4 multi-rotor. We provide high accuracy data and superior deliverables.Our role is to also educate the purchasers of aerial services as to why they need to pay for a good product and more importantly, how they can use the data and confirm its integrity.

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