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Author Topic: PPK without GCP  (Read 3932 times)

ArnsTronic

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PPK without GCP
« on: June 18, 2017, 05:12:01 PM »
Hi
I'm use ppk emlid(accuracy under 2,5cm), flight height 120m, Sony a6000, side lap 80% over 85% I have some doubts about the configurations to get better topographic accuracy.
1. In "Reference settings" 
    Camera accuracy (m) :?
    Camera accuracy (deg) :?
    Ground altitude(m) : I put the base altitude! Is correct?or flight height?
    Marker accuracy (pix) :?
    Tie points accuracy (pix) :?
2. Align image(align key point limit 90, 000;Tie point limit 40, 000),  in highest, high our medium I have some increase of accuracy in full parameters?
    Build dense cloud in medium or hight, I have some increase of accuracy in full parameters?
3. I'll get better topographic accuracy with full parameters in align image or build dense cloud? Because the process time I can use one in full and another in medium.

Thanks
« Last Edit: June 18, 2017, 05:24:19 PM by ArnsTronic »

ArnsTronic

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Re: PPK without GCP
« Reply #1 on: June 21, 2017, 02:02:26 PM »
Please Alexey Pasumansky, help me with values on reference settings.  Thanks

Alexey Pasumansky

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Re: PPK without GCP
« Reply #2 on: June 21, 2017, 02:21:28 PM »
Hello ArnsTronic,

Camera accuracy (in meters and degrees) should correspond to the measurement accuracy (providing that you have loaded the orientation angles information to the Reference pane). So for 2.5 precision you can input 0.025 m.

Ground altitude can be skipped, if you have regular vertical aerial survey. If use, it should represent the average ground surface level above ellipsoid in the selected coordinate system.

Marker accuracy can be left as default, as you don't have markers. Tie points accuracy - you can leave it as default also - 1. Or take the reprojection error value from the Chunk Info dialog after the initial alignment is finished.

As for the parameters, I think that High accuracy would be fine. Key point limit can be used from 40,000 - 80,000 interval, tie point limit - from 10,000 - 40,000 interval. The lower values here (40k, 10k) are commonly used. Use preselection (Generic + Reference) to reduce the processing time.

Dense cloud generation quality effects on the DEM resolution and surface detail level that you can achieve.
Best regards,
Alexey Pasumansky,
Agisoft LLC

pedram55

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Re: PPK without GCP
« Reply #3 on: January 23, 2020, 08:44:04 PM »
Hello
I have installed this PPK module on my Phantom4 and base station was near the project .
i used 10 GCP for 2km * 200 m road ( project was strip ) .
the best result that i got was for 3 points .is it possible to process project without GCP ?
if yes please tell me about setting .
thank you