Please select Into the mobile phone version | Continue to access the computer ver.
DJI Mavic 3E - camera center
1942 13 2023-2-14
Uploading and Loding Picture ...(0/1)
o(^-^)o
Simptonym
lvl.3
Flight distance : 981598 ft
Slovakia
Offline

Hello everyone, I would like to use M3E as a GNSS rover for marking GCPs and for that I need to know how much milimetres is from sensor of camera to front element of lens. Does anyone know this?
(based on inspiration from this with P4RTK https://www.pix-pro.com/blog/post/gnss-rover-drone)
2023-2-14
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

I have already partially answered a similar question.  This might interest you:

https://forum.dji.com/thread-284029-1-1.html

Afterwards, you have to remain lucid, with this kind of method it is a little utopian to want precision levels of the order of a millimeter.  Measure the distance between the GCP and the camera, you should get pretty close.

What do you use?  DRTK2, PPK or NTRIP?



2023-2-14
Use props
Simptonym
lvl.3
Flight distance : 981598 ft
Slovakia
Offline

I am definitely not looking at precision lower than 1cm. I will use RTK (NTRIP) and if not available PPK.
2023-2-15
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Simptonym Posted at 2-15 14:19
I am definitely not looking at precision lower than 1cm. I will use RTK (NTRIP) and if not available PPK.
I am not a native English user.  If you are looking for precision below the centimeter:   You can forget about measuring GCPs with the M3E, and start looking into investing in a GNSS rover receiver and its base station.  

Forget the NTRIP too, you have little chance of achieving precision below one centimeter.  With the PPK it is already more reasonable.  Even if hoping to reach this level of precision with photogrammetry is a bit illusory, it is not impossible.  

Otherwise: The accuracy of NTRIP and PPK will depend on the distance from the base station.  You can once again use your own base station by placing it on a cadastral mark measured beforehand.  Or by connecting to an NTRIP network and doing an average for a while.  It's not PPP, which is the ultimate technique, but it does the job.

Good luck.
2023-2-15
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Simptonym Posted at 2-15 14:19
I am definitely not looking at precision lower than 1cm. I will use RTK (NTRIP) and if not available PPK.



You can send me the dimensions of the position of the M3E camera in relation to the landing gear. I can draw you a platform to print in 3D. Similar to the one I have for my P4R which I use to measure GCPs.
2023-2-15
Use props
Johnnokomis
First Officer
Flight distance : 12749816 ft
  • >>>
United States
Offline

LV_Forestry Posted at 2-15 22:22
[view_image]

You can send me the dimensions of the position of the M3E camera in relation to the landing gear. I can draw you a platform to print in 3D. Similar to the one I have for my P4R which I use to measure GCPs.

Does this gives you every measurement you'd need to draw up this device? I'm very interested in this concept of the M3E to shoot checkshots with.

I'm not sure if it'd help at all but I also have free 3D model of the M3E you can download from Sketchfab. It has no scale reference but everything is proportional in regards to the size.

Mavic 3 Enterprise 3D Model
20230228_133539~2.jpg
20230228_133648~2.jpg
20230228_133705~2.jpg
20230228_133732~2.jpg
20230228_133858~2.jpg
20230228_135016.jpg
20230228_135459.jpg
20230228_135546~2.jpg
20230228_135650~2.jpg
2023-2-28
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Yes it should be enough.  I will draw it tomorrow.
2023-2-28
Use props
Simptonym
lvl.3
Flight distance : 981598 ft
Slovakia
Offline

LV_Forestry Posted at 2-28 12:56
Yes it should be enough.  I will draw it tomorrow.

Also, regular Mavic 3 model is available here: https://www.thingiverse.com/thing:5155706. I guess they are the same.
2023-2-28
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Johnnokomis Posted at 2-28 12:32
Does this gives you every measurement you'd need to draw up this device? I'm very interested in this concept of the M3E to shoot checkshots with.

I'm not sure if it'd help at all but I also have free 3D model of the M3E you can download from Sketchfab. It has no scale reference but everything is proportional in regards to the size.

You will find the 3D printer file. As well as a PDF with a 1: 1 drawing. You can print it or put it on a ladder on a screen to test before wasting plastic if the dimensions are not good. I took up the dimensions you show in the photos. The Symptonym' STL file is not at the scale, Thanks anyway.
M3E_GCP.rar (65.01 KB, Down times: 9)
2023-3-1
Use props
Johnnokomis
First Officer
Flight distance : 12749816 ft
  • >>>
United States
Offline

LV_Forestry Posted at 3-1 01:28
You will find the 3D printer file. As well as a PDF with a 1: 1 drawing. You can print it or put it on a ladder on a screen to test before wasting plastic if the dimensions are not good. I took up the dimensions you show in the photos. The Symptonym' STL file is not at the scale, Thanks anyway.

Thank you for taking the time to make this. I would love to try it out but it's too big to be printed on a normal sized bed. I'll send it off to be printed but my question is, how will the pitch of the drone be affected by this? The RTK module sits at a decent pitch when the M3E is on a level surface. Does the IMU account for this pitch or how accurate is the IMU anyways?
2023-3-1
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Johnnokomis Posted at 3-1 09:41
Thank you for taking the time to make this. I would love to try it out but it's too big to be printed on a normal sized bed. I'll send it off to be printed but my question is, how will the pitch of the drone be affected by this? The RTK module sits at a decent pitch when the M3E is on a level surface. Does the IMU account for this pitch or how accurate is the IMU anyways? [view_image]

If you give me the dimensions of your printer I can split the part.

Theoretically the lever arm between the center of the phase of the receiver and the center of the camera is calculated directly in the drone, according with IMU and compass data. It will be necessary to measure the distance between the GCP and the lens of the camera. I did this way for my P4M, I rounded up to 5cm. It is certainly not the exact value but comparing with a Trimble receiver the results are extremely close.
2023-3-1
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

Johnnokomis Posted at 3-1 09:41
Thank you for taking the time to make this. I would love to try it out but it's too big to be printed on a normal sized bed. I'll send it off to be printed but my question is, how will the pitch of the drone be affected by this? The RTK module sits at a decent pitch when the M3E is on a level surface. Does the IMU account for this pitch or how accurate is the IMU anyways? [view_image]

I split it in 4, you can put it together by putting toothpicks in the grooves and hold everything together with hot glue or PLA/ABS that you just melt on top.

M3E_GCP_Split.rar (81.57 KB, Down times: 2)
2023-3-1
Use props
DRONE-flies-YOU!
First Officer
Flight distance : 1450594 ft
United States
Offline

LV_Forestry Posted at 3-1 10:06
I split it in 4, you can put it together by putting toothpicks in the grooves and hold everything together with hot glue or PLA/ABS that you just melt on top.

Which Mavic 3 Enterprise drone do you have?

Curious if you could test something with the thermal.
2023-3-1
Use props
LV_Forestry
Captain
Flight distance : 4726654 ft
Latvia
Offline

DRONE-flies-YOU! Posted at 3-1 23:55
Which Mavic 3 Enterprise drone do you have?

Curious if you could test something with the thermal.

Mavic 3 is a standard platform shared by all variants of the range. The dimensions of the arms are theoretically the same on all. What can change is the center of the camera. But at a glance between 3E, 3T and 3M, there is no significant difference. At least always included in the accuracy of the receiver.

You can print the PDF contained in the RAR archive, then see if the dimensions are consistent with that of your drone.

If there is need to modify the 3D file, please send the dimensions.
2023-3-2
Use props
Advanced
You need to log in before you can reply Login | Register now

Credit Rules