Can I trust the units ?

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andre
Posts: 19
Joined: Wed Mar 08, 2017 5:42 pm

Can I trust the units ?

Post by andre »

I load an .las with EPSG:32635 coordinates.
then I do some volume calculations on it, and get results like :

Volume: 221.971
Surface: 979.000
----------------------
Added volume: (+)232.278
Removed volume: (-)5.052

none of which contain any units...
how can I be sure that CloudCompare did understand the coordinates correctly, and all numbers are in m2 or m3 and elevation in meters? - is it just given that it is always metric and in meters ?
daniel
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Re: Can I trust the units ?

Post by daniel »

Units are generally not specified in most of the file formats... Therefore CloudCompare works with what we call "implicit units". Which means that coordinates are loaded "as is" from the file, and the user should know what there units are (generally you have some hints thanks to the scale in the bottom right part of the screen, or the point picking tool that allows you to measure the distance between two points, etc.).

All measures are then displayed in the same units as the original cloud coordinates.
Daniel, CloudCompare admin
andre
Posts: 19
Joined: Wed Mar 08, 2017 5:42 pm

Re: Can I trust the units ?

Post by andre »

Thank you, but... now I am confused, coordinates were in EPSG:32635 - then shifted to keep precision on import , scale is 1.0000
are my volume calculations in meter at all then ?
daniel
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Re: Can I trust the units ?

Post by daniel »

The shift won't change the units, and a scale of 1 as well.

Therefore, yes, the units should still be meters.
Daniel, CloudCompare admin
andre
Posts: 19
Joined: Wed Mar 08, 2017 5:42 pm

Re: Can I trust the units ?

Post by andre »

thank you, I did not realize that the coordinates represented meters :)
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