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Author Topic: Camera accuracy parameters (deg and meters) to use with DJI Phantom 4 series?  (Read 344 times)

EV_91

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Hi all,

We're actively surveying several agricultural plots using DJI Phantom 4 Pro v2's, approximately 70 successful flights so far.

In a quest to optimise our processing workflow in Metashape, I'm trying to understand the 'camera accuracy' setting in the reference pane and chunk properties. I'm using the camera pitch, yaw, roll of the Phantom when processing (as in, option to include XMP data is enabled). Three questions:

1) Do I need to specify a ground altitude in the chunk's properties to ensure Metashape does indeed use the camera's pitch/yaw/roll? (read this in an older post here)

2) Default is 10deg and 10m accuracy - does anyone have experience what realistic values for our Phantom should be? I can imagine all distances should be at their default ±10m, but camera angles could be way more accurate given the IMU and gimbal accuracy in these DJI's.

3) The value for yaw seems to be reversed in Metashape. Using e.g. exiftool the camera yaw angle reads 134.7 deg, whilst in Metashape 225,3 deg is reported for the same photo. This does not happen smaller yaw angels (e.g. 74.3 remains 74.3)  What's going on here, does Metashape apply some sort of coordinate transformation?

Even though several topics exist regarding these parameters on this forum, I'm still a bit in the dark.

Thanks in advance, cheers!

Bas
« Last Edit: May 03, 2019, 04:31:55 PM by EV_91 »

Alif

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Dear, technical support

Please give as explanation about this topic, my be your information can answer as about camera accuracy (m) and (degree) too measurements accuracy ( m ) and (pixel). How many numbers must I input ideally when I used camera Sony alpha 5100 capture altitude at 300 AGL including sidelap 75% and overlap 80% when the object are plantation. Please help me.

Alexey Pasumansky

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Hello,

1. Ground Altitude doesn't require to be specified. This parameter is only required to speed up the Reference preselection for very oblique image sets that have orientation angles loaded to the Reference pane.
For near nadir shooting you do not need to input this value.

2. The accuracy values should reflect the measurement accuracy of the particular device used (GPS, IMU).

3. Can you provide any image where you are observing any issues with the meta-information reading?
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Alexey Pasumansky

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Please give as explanation about this topic, my be your information can answer as about camera accuracy (m) and (degree) too measurements accuracy ( m ) and (pixel). How many numbers must I input ideally when I used camera Sony alpha 5100 capture altitude at 300 AGL including sidelap 75% and overlap 80% when the object are plantation.

Accuracy values (in meters and degrees) depend on the device that is recording this values. You should input the values that reflects the measurement precision of the GPS/IMU that is used by the drone.

As for the pixel accuracy values, I do not recommend to change them and leave the default values (0.1 for markers, 1 for cameras).
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Alif

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Dear, Alexey

Thanks for your explanation above, that is mean when camera Accuracy in meter  information from GPS or IMU yes,? So if my GPS or IMU has loads in airframe there accuracy is 5 cm, that I read from mission planning monitor before drone going to the mission what it is true ? .. so we must input 5 cm in camera Accuracy reference settings ( m) ?.

What is the marker accuracy number have been taken from my GPS Spectra / GPS south when measures markers to collecting their coordinate, What is the mean true or not ? Alexey..

One more, I carious with smart seamline feature by agishoft Meta Shape, when my experience process with agishoft Photo Scan is not different yet between them. How is seamline create and wher are seamline build, how is the parameters means. Please tell to me?

Alexey and agishoft I thank of all feedback above because may department needs agishoft solutions,
I has employees company from agribusiness, majority of Drone Acquisition Officer and images processing. Last year I heard this software from internet when the testimony are okay.. from here we are moved to Agishoft. So i hope agishoft can halp us if any something trouble with the software and more information about trick and tips for aerial photography mapping processing basically for agribusiness.

Best regards
Alif