Reference Coordinate System
12030 12 2019-1-23
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GaSurveyor
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Does anyone know what coordinate system is referenced in the details of images captured during flight (p4p pro)? Also is the Altitude referenced A.G.L. or M.S.L. ? Im tring to process images with software and I need to know what im inputing so I can analyze the output files.

2019-1-23
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DJI Gamora
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Hi there, thank you for reaching out. With regards to your concern, the coordinate system being used is WGS84 and for the Altitude, it would be A.G.L where the Aircraft take off.
2019-1-23
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GaSurveyor
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Thank you! Would you happen to know the camera to gps sensor offset in meters?
2019-1-23
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Geebax
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GaSurveyor Posted at 1-23 13:42
Thank you! Would you happen to know the camera to gps sensor offset in meters?

About two furlongs
2019-1-23
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GaSurveyor
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So what your saying is you have no idea?
2019-1-23
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Geebax
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Australia
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GaSurveyor Posted at 1-23 14:22
So what your saying is you have no idea?

Yeah, I am in fact sending up your quesation. You will not get answer to technical questions of that nature on here anyway, there are no DJI technical people participating in this forum. If I were to take a guess, I wouls say 6 centimetres in the vertical plane.
2019-1-23
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GaSurveyor
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Thanks. The processing software Im trying out needs this offset.
2019-1-23
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Labroides
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Flight distance : 9991457 ft
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GaSurveyor Posted at 1-23 14:47
Thanks. The processing software Im trying out needs this offset.

And the DJI people that are here have no idea.
Any information they give is often incorrect, like the altitude info they gave you.
The altitude data in the exif info for each image is from GPS and it is MSL.
The altitude you see on your screen is from barometer and is relative to the launch point.

I've never heard a figure for camera/gps offset but if you need it, you might be able to work it out from some testing?
2019-1-23
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GaSurveyor
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Is this information not available in the specs somewhere? Kind of hard to fly with eagles when your soaring with buzzards!
2019-1-23
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Geebax
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Australia
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GaSurveyor Posted at 1-23 15:08
Is this information not available in the specs somewhere? Kind of hard to fly with eagles when your soaring with buzzards!

It is a consumer level device, try getting complex technical details out of Apple or Samsung.
2019-1-23
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GaSurveyor
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Labroides, as far as the altitude goes it does not appear to be M.S.L. or A.G.L. . The ground level M.S.L. in the area I flew was around 1100' above M.S.L. or 335.28 meters above M.S.L. collected by a independent survey grade GNSS receiver with rtk corrections from a state wide network. My flight plan was set to run at 185' A.G.L. or 56.388 meters A.G.L. . I know the GPS in the p4p is uncorrected meaning it receives no corrections from a ground base station or gps network but it is much further off than I would expect. Generally in a autonomous gps receiver (which is what the p4p has) elevation is within 50' or 15.24 meters. I'm just trying to understand exactly what kind of data i am working with so that i can yield the most precise results. Thanks for any help.
2019-1-23
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Labroides
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GaSurveyor Posted at 1-23 15:08
Is this information not available in the specs somewhere? Kind of hard to fly with eagles when your soaring with buzzards!

What software are you using?
The mapping software I'm familiar with manages perfectly without having to give it that sort of data.

You've told me what height your flight was at but not mentioned what height was in the exif info?

The info I gave you in post #8 has been correct as long as I've been using a Phantom for mapping missions.  

I should have also mentioned that the height is shown in metres.


2019-1-23
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irfan-ul
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Ireland
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Hi,
We have a matrice 300 drone and i am using the stereo camera and imu both with dji-osdk-ros......my question is what is the coodinate system is fixed for IMU & cameras by DJI ??
Thanks!
2023-9-7
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