[pdal] Extract terrain from TLS point cloud

[Silvia Franceschi]

Thank you Luigi!
I will follow you suggestions, "just" have to understand clearly the
commands you referres to in the slides.
Unfortunately I didn't know that there where also commands for normal and
so on, so what I did until now is more or less what there is in slide 12.
Regarding slide 13-14, didn't even know about the existence of the
command filters.normal and filters.kdistance. I will read them carefully
and then try to apply to my dataset.
I think that I will for sure sure ask for more help, but in any case I will
let you know how it works.

Many many thanks again!!!

Silvia


On Mon, May 13, 2019 at 9:24 AM Luigi Pirelli <luipir at gmail.com> wrote:

> we had similar problems with TLS in urban context regarding first part pf
> the cars
> you can see our strategy to clean the first PMF effect in slides from
> http://slides.com/darango/deck-10-11-12-11-12#/11
> to
> http://slides.com/darango/deck-10-11-12-11-12#/1
> <http://slides.com/darango/deck-10-11-12-11-12#/11>5
>
> the main idea is to do noise cleaning, PMF, filter on normal, filter on
> kdistance, PMF again
>
> not clear to me if you can have a good discrimination of the ground part
> of the threes using normals due to nature of these surfaces.
>
> cheers
>
> Luigi Pirelli
>
>
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>
> On Sat, 11 May 2019 at 10:01, Silvia Franceschi <
> silvia.franceschi at gmail.com> wrote:
>
>> Dear all,
>> I am trying to extract the ground points from a point cloud of a
>> terrestrial laser scanner (TLS) in a forestry environment, but the result
>> is not so good as the one I got using data from ALS.
>> What I did is:
>> 1. denoise the dataset using the filter.outlier and a filter.range for Z
>> ranges:
>>             "type": "filters.outlier",
>>             "method": "statistical",
>>             "multiplier": 3,
>>             "mean_k": 8
>> 2. apply a filter.elm and a filter.smrf to the cleaned dataset
>> For the SMRF filter I used these parameters:
>>             "type": "filters.smrf",
>>             "slope":0.2,
>>             "window":16,
>>             "threshold":0.45,
>>             "scalar":1.2
>>
>> Unfortunately the resulting ground points contain also the first part of
>> of the trunks of the trees, how is it possible?
>>
>> I am doing some testing changing the values of the SMRF parameters but
>> the results are almost the same.
>>
>> Do some of you have experience with such kind of data? Am I missing some
>> operation for filtering? Could you please help me understanding at least
>> where to focus the attention to try to obtain something...
>>
>> Thank you in advance.
>>
>> Silvia
>>
>>
>> --
>> ing. Silvia Franceschi
>> Via Roma, 64
>> 38030 Castello di Fiemme (TN)
>>
>> tel: 0039 -3384501332
>> _______________________________________________
>> pdal mailing list
>> pdal at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/pdal
>
>

-- 
ing. Silvia Franceschi
Via Roma, 64
38030 Castello di Fiemme (TN)

tel: 0039 -3384501332
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