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Photogrammetric camera calibration
1462 4 2020-1-7
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Billboyheritagesurvey
Second Officer
Flight distance : 232306 ft
United Kingdom
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As part of the image processing workflow I have conducted a calibration procedure for the Mavic 2 Pro: https://billboyheritagesurvey.wordpress.com/2020/01/07/l1-20c-calibration/

I wonder if any other Mavic 2 Pro operators have any comparable data available?  

                        
Parameter
                 
                        
value
                 
                        
SD
                 
                        
Unit
                 
f
10.26mm

Exif mm                         
fx                                          
4479.94
2.26513
              
f in px
                 
fy                                          
4374.51
2.15679
cx                                          
2727.48                         
0.813274
            
                        
principal point px
                 
cy                                          
1811.92
0.719281
skew                                       
-1.91657                         
0.0843506
                        
                 
k1                                          
-0.0196948
0.00126486
                        
                        
Radial distortion
                 
k2                                          
0.00652119
0.010933
k3                                        
0.0909295
0.0368218
p1                                          
0.000237354                           
2.27565e-005
                        
Tangential distortion
                 
p2                              
0.00108494
3.73953e-005


2020-1-7
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izotop
Second Officer
Flight distance : 194954 ft

Slovenia
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Very interesting.
So far i only use m2p with pix4dcapture and photoscan for some photogrammetry with old building for cloud points import to use in architecture, but would be interested to find out more, how make results even more precise etc. So, this data is imported to photoscan to correct lens curvature etc, right? Is this not autocorrected via photo import allready?

Here you will maybe find some info, this guy test few prosumer drones for photogrammetry work and re-done test for m2p after exif update was done, so it works correctly:


you can use english subtitles. He also have some other great videos.

As i remember, m2p takes 3rd place in accuracy, after p4p and parrot. But i must say, i was impressod wirth resoults. Now, i only wish they make droneharmoony app with 3d routing cheaper, as i don't need all that pro stuff..

Great blog, by teh way, must read the content about this whole geodata stuff..
2020-1-7
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Billboyheritagesurvey
Second Officer
Flight distance : 232306 ft
United Kingdom
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izotop Posted at 1-7 14:38
Very interesting.
So far i only use m2p with pix4dcapture and photoscan for some photogrammetry with old building for cloud points import to use in architecture, but would be interested to find out more, how make results even more precise etc. So, this data is imported to photoscan to correct lens curvature etc, right? Is this not autocorrected via photo import allready?

Hi Izotop,

Metashape applies an automatic camera calibration on image alignment as part of the standard workflow. If a separate calibration is carried out with the same lens/camera on a controlled target array (chessboard) a higher precision can be achieved.

From the manual:

"After you have saved the calibration parameters for the lens, you may proceed with the workflowsteps in a separate chunk for the actual image set captured by the same camera and lens. To protect the calibration data from being refined during Align Photos process one should check Fixcalibration box on the Initial tab for the chunk with the data to be processed. In this case initialcalibration values will not be changed during Align Photos process"

What I'm keen to know is if there is any variation in these values at different distances/ exposures.


In the video clip no GCPs were used. This might save time but for mapping it is essentail to use GCPs. It is  well known the P4Pro has a better GPS system than the Mavic.


I'd like to know more about what the minimum density of GCP should be for the Mavic, in theory 2 should provide a base scale but I have not tested beyond this yet.

2020-1-8
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izotop
Second Officer
Flight distance : 194954 ft

Slovenia
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aha, thnx for clear this out. for me, mapping etc is not that important, but would like to achieve as much high object precision as  possible via photogrammetry (this is where more precise lens calibration probably does help, also).
2020-1-8
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Billboyheritagesurvey
Second Officer
Flight distance : 232306 ft
United Kingdom
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izotop Posted at 1-8 05:32
aha, thnx for clear this out. for me, mapping etc is not that important, but would like to achieve as much high object precision as  possible via photogrammetry (this is where more precise lens calibration probably does help, also).

You are correct, lens calibration will alpply to all types of phtogrammetric data.
2020-1-8
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