CloudCompare forum

hello

The following calculation results were obtained using '2.5D Volume calculation tool'.

Volume: 63.964
Surface: 51.463
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Added volume: (+)64.839
Removed volume: (-)0.875
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Matching cells: 94.0%
Non-matching cells:
ground = 5.5%
ceil = 0.5%
Average neighbors per cell: 8.0 / 8.0

To get close to the correct volume, should Matching cells be close to 100% and Non-matching cells be close to 0%?
Or is there something more important?

Most of the time, but not all the cases, optimum volume and area is when % of matching cells is close to % of shape area to area of containing rectangular (min x min y, max x max y)
and it is tricky
You can use try and error or visual inspection
Usually, you start with samll grid and increase till you get constant volume

Yes, to achieve accurate volume calculations, having Matching cells close to 100% and Non-matching cells close to 0% is crucial, as it indicates a high level of correspondence between the calculated and actual volumes. However, also consider the precision of the tool and the data quality used in the calculation.

Well, matching and non-matching cells mostly indicate that the overlap between the 2 clouds is not 100%

What's most important is the 'Average neighbors per cell' (maximum is 8 - any lower value indicates that there might be holes, so potentially missing points between 2 cells, and thus probably a too small step value). Ideally it should be above 7.

But I like the process described by DA523, by reducing the step value step by step and look for a stable volume estimation.

DA523, the diagram is very helpful. Thank you for the easy-to-understand diagram and explanation.
TobyAdam, thank you for calling attention to quality.
daniel, I missed the important point in Results. thank you for teaching me.

I adjust the 'step' and note the Results.
I'm happy to get closer to getting the correct values.

Take care !!
2.5d volume has limitations
Please check the attached example where 2.5d volume fails because 2 z levels in the same pointscloud
real volume=2.964 cubic units

Hello da523

Easy to understand,
Does this mean that the calculation will be incorrect if there is an overlap between top and bottom?

2.5d volume between red and blue pointsclouds
x means 2.5d volume incorrect

Thank you very much!
It's a really easy to understand diagram.
I also came close to getting it correct.