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?
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
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@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?
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
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
–
Nuno César de Sá
+351 91 961 90 37
Using the libLAS utility ‘las2las’ you can filter out only those points with classification “ground” (the classification value is 2) like so: las2las in.las --output=ground.las --keep-classes 2 You can find all the point classes in this doc:
···
On 05/15/2015 04:40 PM, Adam Laža 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.
http://www.asprs.org/a/society/committees/standards/LAS_1_4_r13.pdf
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?
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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On Fri, May 15, 2015 at 10:35 AM, Nuno Sá <nunocesardesa@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@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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grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
--
Nuno César de Sá
+351 91 961 90 37
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Hey Anna
Yes, I thought of that but the coarse models I would have access would be the STRM which has 10m vertical accuracy, plus that is Height above ellipsoid I think, so I would have to convert it using the geoid ondulation meaning I would have another error (or am I mixing topics here?). So besides all the difference between data I would have increasing error sources in everything.
Making a DTM based on random points on locations where I know the ground is would lose the ability to detect height variations within high canopy covers but could be an approach since ground heights are otherwise unavailable?
All the best!
Nuno
···
On 15 May 2015 at 20:45, Anna Petrášová <kratochanna@gmail.com> wrote:
–
On Fri, May 15, 2015 at 10:35 AM, Nuno Sá <nunocesardesa@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
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
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
On 15 May 2015 at 14:40, Adam Laža <ad.laza32@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?
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
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
–
Nuno César de Sá
+351 91 961 90 37
Nuno César de Sá
+351 91 961 90 37
On Fri, May 15, 2015 at 9:40 AM, Adam Laža <ad.laza32@gmail.com> wrote:
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.
Hi Adam,
this is an older post but it might still be useful for you or other to know
that v.lidar.mcc [1] which is currently in addons can actually classify
without the information about returns which is what v.lidar.edgedetection
[2] and friends require. The examples look promising (I created them with
actual lidar data, however).
Best,
Vaclav
[1] https://grass.osgeo.org/grass70/manuals/addons/v.lidar.mcc.html
[2] https://grass.osgeo.org/grass71/manuals/v.lidar.edgedetection.html