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Author Topic: Controlling non-RTK data using RTK sensor data of the same area  (Read 4753 times)

mks_gis

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Hi,

Given a RTK enabled high-res system (Sony RXII on WingtraOne with PPK in this case) and a non-RTK system (MicaSense Altum on WintraOne Gen 1, hence no PPK) and given that the same area is flown, can the RTK data be used to control the non-RTK data, without manually deriving GCP from the RTK system processed data? When imaging intertidal areas creating GCP is often not possible due to mud/tides/access. In a test case I did have 6 GCP in the area, but not well spread out due to aforementioned constraints. But in future we may not be able to put out GCP.

What would the workflow be here? Can the RTK RGB and MS data be processed together, using the RTK RGB images as a 'scaffold' for the MS in a multi-camera setup?

Thanks
M


Paulo

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Re: Controlling non-RTK data using RTK sensor data of the same area
« Reply #1 on: June 29, 2023, 07:30:39 PM »
Hi,

i would certainly try to process the RTK RGB + MS non RTK together. If the resolution between the 2 sets of data is similar, then Agisoft should match points between these sets and thus the accuracy of RTK will propagate to MS images...
Best Regards,
Paul Pelletier,
Surveyor

mks_gis

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Re: Controlling non-RTK data using RTK sensor data of the same area
« Reply #2 on: June 30, 2023, 11:05:18 AM »
Thanks for posting. I tried that already, MS only aligned the Sony data, not the Altum, unless I got the workflow wrong in MS.

Paulo

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Re: Controlling non-RTK data using RTK sensor data of the same area
« Reply #3 on: June 30, 2023, 09:30:21 PM »
Ok,

you can look at average GSD for both data sets,,, see if they are very different....

If you are flying both WingTra Sony RGB and WingTra Altum MS at same altitud, then the GSDs between 2 sets will be more than 3 times different and thus matching between 2 sets will not be feasible.

For example a Altum MS flown at 118 m will have a GSD around 5 cm:

Number of images: 1,266
Flying altitude: 118 m
Ground resolution: 0.0517 m/pix
Coverage area: 1.19e+05 m²
Camera stations: 1,248
Tie points: 122,137
Projections: 1,395,661
Reprojection error: 0.331 pix
Camera Model Resolution Focal Length Pixel Size Precalibrated
Altum, Blue (8mm) 2064 x 1544 8 mm 3.45 x 3.45 μm Yes
Altum, Green (8mm) 2064 x 1544 8 mm 3.45 x 3.45 μm Yes
Altum, Red (8mm) 2064 x 1544 8 mm 3.45 x 3.45 μm Yes
Altum, Red edge (8mm) 2064 x 1544 8 mm 3.45 x 3.45 μm Yes
Altum, NIR (8mm) 2064 x 1544 8 mm 3.45 x 3.45 μm Yes
Altum, LWIR (1.77mm) 160 x 120 1.77 mm 12 x 12 μm Yes

While the Sony RX flown at same altitud will have GSD around 1.5 cm:

WingTra with 42 MP Sony RX1RM2            
         
IMAGE Format Full            
 Alongtrack   24.008   mm   5304   pixel
crosstrack   35.994   mm   7952   pixel
Pixel   4.53   µm   4.53   µm
Focal lenght   35   mm   36.8   
            
GSD   1.5   cm      
HeightAGL   116   m   381   ft

I would recommend if you fly your Wingtra Altum at 100 m for example  then fly the WingTra Sony at 300 m if you can...Then matching can be feasible between RGB visible and MultiSpectral...
« Last Edit: July 02, 2023, 06:22:15 PM by Paulo »
Best Regards,
Paul Pelletier,
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mks_gis

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Re: Controlling non-RTK data using RTK sensor data of the same area
« Reply #4 on: July 03, 2023, 11:15:14 AM »
Thanks, that makes sense. However, that negates the accuracy benefits of the Sony, and flying at 300m isn't feasible without a very expensive OSC in the UK.

Manually derived GCP from the Sony is the best way forward then, if visible on the Altum.

Paulo

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Re: Controlling non-RTK data using RTK sensor data of the same area
« Reply #5 on: July 03, 2023, 11:50:33 AM »
Depending on your needs could always fly at 50 m MS and 150 m RGB and would get 1.9 cm GSD visible and a bit more than 2 cm Multi....
Best Regards,
Paul Pelletier,
Surveyor