About Volume calculation Results

[SAYURI]

hello

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

Volume: 63.964
Surface: 51.463
----------------------
Added volume: (+)64.839
Removed volume: (-)0.875
----------------------
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?

[DA523]

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

Screenshot_2024-06-18-13-57-30-113_com.simplemobiletools.draw.pro.jpg (40.62 KiB) Viewed 7996 times

[TobyAdam]

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.

[daniel]

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.

[SAYURI]

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.

[DA523]

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

Screenshot (308).png (90.41 KiB) Viewed 7909 times

2.5d volume fails.zip

(1.38 MiB) Downloaded 628 times

[SAYURI]

Hello da523

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

[DA523]

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

25d.jpg (105.39 KiB) Viewed 7734 times

[SAYURI]

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