Hello
Does having an RTK drone improve results, mitigate bowling?
Is having RTK and GCP better than just GCP?
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Oof… quite the question. There are tons of articles on this out there, so give it a search in your favorite search engine and poke around to see what other industry folks have to say about this matter.
Personal opinion time:
- RTK/PPK GPS data do improve absolute and relative accuracy. Will it mitigate bowling due to Rolling Shutter or overly-aggressive self-calibration? I don’t think so.
- Yes. But is it enough to matter or justify the cost/complexity for your application?
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I think just having various orientation flight paths, overlapping with some difference in height AGL, and some non-nadir images mixed in makes for no bowling. I’ve not seen any bowling in my orthos covering up to several square kilometres, with no GCP or RTK/PPK.
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I agree with Gordon, but would add one more thing. Reduce flight speed to around 8 mph. My drone has a rollong shutter and found this helpful.
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It really depends on the CMOS readout time, slower readout necessitates slower flying. Some big jobs just are not doable at such slow speeds though, due to the time it would take, budget, weather etc limitations.
In the example I mentioned above, I had flight speeds up to 40km/hr (22mph), and rolling shutter distortion wasn’t too significant with my M2P.
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Good point. I guess if I were to fly 100+ acres, I would set the elevetion at 372 and put the speed at 16 mph. I’ll have to test it.
Thanks.
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Bowling can be mitigated by :
- Conducting flight plans with slightly tilted camera
- Double grid + slightly tilted is even better
- RTK +
--gps-accuracyoption to centimeter value can also help
Yann
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What high accuracy GPS receiver setup do you use? I am looking at the Emlid Reach RS+. Reach RS+ by Emlid | RTK GPS receiver for high-precision surveying.
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Got an Reach RS2, the rs+ isn’t good enough.
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Emlid has some great videos explaining the difference between the single band and dual band units. Single band RS+ units are just as accurate as the dual bands in open areas with good sky view. Unless your collecting GCPs in a forest or city then the RS+ is more then adequate. I think there is a big misconception about dual band accuracy.
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Multi band gives you faster fix and you can have a longer baseline.
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Andreas and rderks,
Do GPS receivers, similar to RS+ or RS2, work without an NTRIP subscription? I originally thought that using these type units would give some level of accuracy without connecting to NTRIP. I have an Evo II Pro Enterprise with an RTK unit and was trying to decide between an expensive NTRIP subscription or and Emlid receiver. But, most Emlid instructional videos make it seem like both are needed. Are both necessary to achieve 6- to 12-inch accuracy? I really just want to get down to 1-foot accuracy.
Regards,
Gerry
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You get about 0,5 meters without ntrip. Around 1-2 cm with.
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Does your evo log raw rinex data? Also I don’t think an emlid unit Lora radio will communicate with your evo.( you could inquire with emlid). If your evo logs raw rinex and records event messages with the shutter then you could use the emlid base (rs2) with it logging raw data and use Emlid studio to ppk the data from both receivers and tag the photos with the corrected position. This method is provides excellent results. Are you looking for high relative accuracy or absolute accuracy?
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Kuker Ranken makes me believe the Evo II works with Emlid. But, I will double check.
Hmm, I get .6 with my RTK currently. But, I’m sure construction jobs require centimeter accuracy.
Thanks.
So from what I can see you will need to set up an NTRIP caster with the base and connect the drone to the ntrip caster (all requiring an internet connection). So not very handy unfortunately. I am pretty sure emlids lora radio connection is proprietary and works only with there lora radios. I’m also thinking the evo does not have a Lora radio built in. I would try posting some questions in the Emlid forum and also research the Evo a little more.
As far as accuracy is concerned there are different versions of accuracy. One is relative accuracy referring to the reconstruction of the model and its measurements. eg. pile volume and measurements are accurate. The other is absolute accuracy meaning that the model and it’s geographic coordinates line up with the actual location on the planet and in the desired coordinates system and elevation model. This is a much more complicated target to shoot for and involves more knowledge of coordinate systems , ellipsoids, Geoids etc. For centimetre accuracy in this area you need GCPs and Check points collected very accurately and with a good working knowledge of geographic and gnss systems.
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Rderks,
The statements below are not meant to be interpreted as if I am a “know-it-all”. I am here to learn from this communities experience on what works and what does not.
I really appreciate all the research and time you have put into my questions. Just to let you know, I have been working with GIS for over 25 years. I am well versed in ArcGIS, AutoCAD, QGIS, coordinate systems, datums, ellipsoids, and so on. I love this WebODM community, simply the best folks. I am an independent trying to find a cost effective way to serve different industries, and the levels of accuracy that each require without spending a fortune. My goal is to break into construction mapping support and NOT surveying. You might be a surveyor, so accurate and precise is your forte. As a GIS professional, I just want to deliver accurate (orthomosaic) OR precise (3D model).
I really like that graphic!!
Regards,
Gerry
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