Exporting Phantom 4 RTK maps

Was wondering what the EPSG codes are for when you go to export a map? How would I even know which one to choose? Im gonna be using a Phantom 4 RTK to get my images and located in Iowa. Need to info off the maps to compare over time. I just want to make sure I use a correct one or one that will work for my needs. Any help would be great.


What town are you in? What are the maps for?

Sioux City, Ia Will use the maps to see elevation changes on construction site over time.

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If they are using the most current data it should be this. If it is different then they either are using an old projection or a specific one to their area. You will also want to be using Geoid18 if you are using any type of control or check points.


Wow. Thank you sir. Is there a place I can go to look up that info in case I find some work at another location or state?

If you click on the image it will take you to Iowa codes. Just epsg.io and type in the state and “nad83(2011)”. They are separated into zones. Iowa has two and Texas has five. Souix City is obviously north but sometimes it’s tough to tell which one if they are close. We are in Austin which is very close to the transition from the Central to the South Central zones.

Most importantly are looking for ftUS/sFT, United States Survey Feet. One International foot equals 0.999998 U.S. Survey feet and will make small (seemingly unexplainable) horizontal shifts. Hopefully you will never run into a Surveyor/Engineer team that uses them. I literally had one last week and 10+ years before that.

Perfect! I never knew. Glad there are kind people like yourself willing to help out people like me. I love learing about all this as I go. Thank you so much!


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This is at least as much fun for me as babysitting a drone :slight_smile: .

So if im in the middle of no where, no ntrip service, cell service or even a Kum&Go if i set up the base station and let it sit for a while, i can get that points measurements if i add the antenna height to the info correct? Being able to mark my unknown point.

Are you talking about the D-RTK 2 base?

Yes sir. Being able to mark a unknown point with it or a gcp

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That’s what I was afraid of. The best thing you can do is setup the base with an averaged coordinate and then use the drone as a rover. Make sure to document the averaged coordinate so you can manually input it on future visits. The longer you can averaged the coordinate the better it will get but will not get much better than a meter at best. If the map needs to match an outside piece of information like a CAD file then you need a couple of reference points to align the drone data affect the fact.

So really what is the purpose of the base station. If i understand correctly, if im in an area with ntrip connection, i would just connect to drone and ntrip thru the controller and get my corrections from that. Right? Every video I see on YouTube has some guy just set up the base station, connect to the drone and fly and thats it. But i have no idea of what corrections they would get.

The base is most helpful for these situations where you don’t have service but also when you are very far from the CORS locations. We run a local base when we get to 10 miles. I have come across many drone mappers that are using CORS 15-20 miles out but they have to expect the lesser accuracy and repeatability. Texas is a big State so it’s easy to get too far. As you said when you have NTRIP capability you can connect the drone but you can also connect the base and use it as a rover. This is the most common scenario today.

Ok. Thanks for your input. I think, and i mean think, I’m starting to understand all this now.


If i was to add a single AeroPoint in, along with the Dji Base station and Phantom 4 Rtk that should give me accurate data to produce my elevation map in DroneDeploy. I could then tie in the corrected images from the drone along with the CVS file from the AeroPoint board into Drone Deploy.

That would probably work. If you collect the point with the AeroPoint PPK you can grab the coordinate they derive and manually enter that manually for the D-RTK 2 in the future as well.