Hello. Interesting problem here mapping a 1.7-acre area to obtain soil stockpile volumes.
We used the default height (60m) and overlap (75/75) on this flight. Stitched image looks good, but the elevation change between the surrounding surface and height of the piles (and consequently, the volumes) was grossly underestimated. The highest point of the piles is easily 30ft but the mapped change in elevation from the perimeter area to the highest point of the piles was 2ft.
I've read that 80/80 overlap is recommended, but given that 75/75 isn't that far off, should that make this much of a difference? Here's the overlap report image. I assume the white spaces are no data at all? If that's the case this doesn't look great.
Were we flying too high? I've read that the height should be "at least" 4-5x the height of the tallest feature in the mapped area. Were we too high at 60m? (30ft x 5 = 150ft or 45.7m) I don't quite understand how the software is able to model terrain from these images, but is it possible that we were flying too high for sufficient resolution needed to process the overlap and get those elevations?
Another possibility I read about was homogeneous colored surfaces. Could the tarps have been the problem here?
Thanks for any thoughts you may have.