NAD83 LLH in, NAD83 UTM out? (NTRIP/GIS question)

When my DJI RTK drone is connected to NTRIP, it receives a NAD83(2011) reference frame from our regional network. Thus my understanding is that the exif tags for photo positions are also referenced to NAD83 even though the exif data reports as WGS84.

That said, should I expect that the UTM deliverables from ODM be also referenced to NAD83(2011)?

I understand that ODM assumes all inputs and outputs in WGS84. If my hypothesis is correct, I could simply change the CRS in QGIS and have an end-to-end workflow in NAD83. If there’s something more than a conversion that happens within ODM, I’ll go back to the drawing board.

Any thoughts?



As I’ve understand it the ntrip corrections is in wgs84 and the projection is applied in the device.

At least that is how it works on a gnss receiver with a field collector. I do work as a construction surveyor but I’m not an expert on gnss.

The DJI Phantom 4 RTK at work has no setting for projection so it’s WGS84 in the exif.

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That’s what I originally thought too, though more research suggests that the rover adopts the reference frame of the network, which seems to show up with an offset in my RTK deliverables when compared to those using WGS84 coordinates in my base.

I have a support ticket open with my DJI dealer as well, though they’ve been slow to confirm an answer on this one. Would be great if anyone has a definitive answer!

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Have you checked with the ntrip supplier?

Sometimes you need a special token to get the right data, the ntrip I have has different data streams for different protocols.

And the corrections might be adapted for a certain projection. It also has to take continental drift in consideration.

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My NTRIP provider has several mountpoints and it appears each of them is configured for a various purpose. Our usual surveying mountpoint outputs a NAD83 UTM Zone 17 coordinate system with ellipsoidal height and we use this with our gnss rovers. However that mountpoint doesn’t use RTCM3.2 format, but fortunately they offer one with an RTCM broadcast with the same coordinate system output. We pay a monthly fee for this service and we have a login/password for each antenna, whether it is a drone or a rover.

I don’t fully understand how it is all setup as our provider provides almost zero documentation. All I can say is we have verified everything is jiving pretty closely in the field, except for some remaining elevation error I am trying to fix.

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I seriously don’t think ntrip is meant for simpler rtk drones.

One thing you could try is set up your own base.

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