Agisoft Metashape > Camera Calibration

GSD ground sampling distance for statues

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hanscastrop1@gmail.com:
hi all,
is ground sampling distance for 'true' 3d objects usefull? is the figure we get on page2 report the average?
  want to get a kind of level of quality that can be compared.

thanks,
HansCastrop

Alexey Pasumansky:
Hello HansCastrop,

To estimate the flight altitude value for the report Metashape performs the following operation: at first it estimates the average distance from the camera center to the sparse cloud points that have valid 2D projections on the given photo and then takes the median value for all the aligned cameras in the project.
The ground resolution value for the report is also estimated individually for each camera first as the flying altitude (like previously described) multiplied by the angular resolution of the pixel. Then the value is averaged for all cameras.

So the value can be properly considered for aerial survey projects, whereas for close range projects (like scanning monuments) it may be incorrect.

159Alex951:
Hello Alexey,

Does this mean that if I have a close range project (like scanning monuments) the flight altitude is actually referring to the distance from my camera center to the monument itself?

Best regards,
Alexander

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