''percentile'' option in lasthin

[Kalliopi Koutantou]

Hello all,

I have a misunderstanding regarding the ''percentile''option in lasthin.

I am using the percentile -30  and the -classify_as_8 parameters,

wishing to classify with the tag 8 all the points which are close to the 30% of elevations,

as desscribed here: https://rapidlasso.com/2019/08/18/removing-low-noise-in-lidar-points-with-median-ground-surface/

But what I see in the readme file description, is that the -classify_as_8 option 

includes the thinned out points, and not the ones who pass the 30% filtering.

What is correct?

I suppose the second one, because otherwise I get only few points in the final PC, whereas it should be at least one per 0.5 pixel.

Thanks in advance!

Kalliopi

[Martin Isenburg]

Hello,

the command

lasthin

-i ..\data\france.laz ^

-step 1 ^

-percentile 30 ^

-classify_as 8 ^

-odix _p30 -olaz

will give you for each square meter the point that is closest to the 30th percentile height measured against the other points that fall into this same square meter. You seem to be interested in getting additional points that are close to percentile 30? One way of doing this would be to also compute percentile 29 and percentile 31? In this example here this goes from 9994 points to 10677 to 11074 points after adding the two calls shown below.

lasthin ^

-i ..\data\france_p30.laz ^

-step 1 ^

-percentile 31 ^

-classify_as 8 ^

-odix _p31 -olaz

lasthin ^

-i ..\data\france_p30_p31.laz ^

-step 1 ^

-percentile 29 ^

-classify_as 8 ^

-odix _p29 -olaz

Regards,

Martin

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