[GRASS-user] Classified point cloud from UAS

[Anna Petrášová]

On Fri, May 15, 2015 at 10:35 AM, Nuno Sá <nunocesardesa at gmail.com> wrote:

> I've got the same questions :)
>
> How will you get the DTM if you don't have info on the ground ?
>
> I did some search for publications but couldn't find if there were any
> methods just by using UAV data, do you have any recommendations?
>
> Ciao!
> Nuno
>
> On 15 May 2015 at 14:40, Adam Laža <ad.laza32 at gmail.com> wrote:
>
>> Hi all,
>>
>> I've got some data from UAS (SenseFly eBee) exported as point cloud. I'd
>> like to ask if there's any way how to classify the data in GRASS. As an
>> input I have a point cloud exported in .las or .txt file. As an output I
>> need another .las file containing only terrain (I need to filter out
>> objects, buildings and vegetation) for next step which is generating DTM.
>>
>> I've already tried some modules, import(r.in.lidar, v.in.lidar) works
>> well. Then I focused on v.lidar.* modules (v.lidar.edgedetection,
>> v.lidar.growing, v.lidar.correction) but already the first step of
>> recognizing and extracting object didn't work for me. I suppose it's due to
>> the v.lidar.* modules need data only from LiDAR, but I have data from
>> phtogrammetry (eBee carries Canon RGB camera).
>>
>> Any idea how to classify my data?
>>
>
Hi,

I haven't tried v.lidar.* modules, because I typically work with already
classified lidar, what exactly was the problem?

Generally, you it would be difficult to get ground from UAV data because
the point cloud represents only surface (unlike lidar where you get
multiple returns). You could compare the point cloud with some coarser
digital terrain model and high differences would mean that there is some
vegetation or buildings.

Anna


>> Thank in advance,
>> Adam
>>
>> Data sample at google drive:
>> las:
>>
>> https://drive.google.com/file/d/0B3qa8r8b0sq0TTdnSVNHdE1UQ2M/view?usp=sharing
>> txt:
>>
>> https://drive.google.com/file/d/0B3qa8r8b0sq0NVFRMmNEZHNkbDA/view?usp=sharing
>>
>>
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>
>
>
> --
>
> Nuno César de Sá
> +351 91 961 90 37
>
>
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