Calculating volume error from GSD or GCP ?

[wizprod]

Hi,

I want to provide a customer with error percentages for a volume-calculation from photogrammetry.

As Photoscan lack this functionality, I have to do this manually.

Going from this https://support.pix4d.com/hc/en-us/articles/202559219-Error-estimation-in-volume-calculation .

I use the area-measurement (after having made a perimeter and click Measure) and time it DEM GSD*1.5.

But several questions arises:
- Should I use the GSD of the recorded images (0.88 cm/pix in this case) instead of the DEM's 1.6 cm/px ?
- Should I be using the GCP z axis error instead?
- I have scale bars in this project too, which has less errors than my GCP, but can their errors be used for this purpose?

Currently I average the error of the GSD and GCP before making the percentage calculation.

[wizprod]

Bumping this one. Anyone?

[wizprod]

Trying one more bump!