[GRASS-user] Using GRASS on a ply file

mlennert · June 7, 2018, 7:10am

Hi Marion,

Please keep the discussion on the list.

Am 7. Juni 2018 06:55:33 MESZ schrieb marion-brunet@sfr.fr:

Thank you very much for your answer! 
However, I have another ERROR when I use the command , even when
I  remove the white spaces. My command is: 
v.in.ply input=path\file.ply output=test 
and I get: 
 
AttributeError 
: 
'exceptions.UnicodeDecodeError' object has no attribute 
'value' 
 
I really don't know what it means..

I have the feeling that you provide us with only an extract of the message. Please provide the complete traceback and the exact command you used.

If you launch the command via the GUI you can find the history of commands in the console window (up arrow to see previous commands) or you can use the 'copy' button in the module GUI to copy the command line just before pushing run.

Moritz

.

<div class="gl_quote" style="margin-top: 20px; padding-top: 5px;">De :
"Moritz Lennert" 
A : marion-brunet@sfr.fr,grass-user@lists.osgeo.org 
Envoyé: mercredi 6 juin 2018 13:49 
Objet : Re: [GRASS-user] Using GRASS on a ply file 
 
<div class="gl_quoted">Hello Marion and welcome to the GRASS community
! 
 
On 06/06/18 12:03, marion-brunet wrote: 
> ‌Hello, 
> 
> I have two point clouds of an open-pit mine taken a few weeks
apart. I 
> would like to estimate the volume that has been excavated during
that 
> interval, i.e the difference between the two point clouds. For
that I 
> used CloudCompare to get a new point cloud corresponding to the
distance 
> between the first two clouds. Now I need to know the 
> Z information of each point of this last cloud. I want to use
GRASS to 
> do it, but I can't find a method that is working... 
> 
> The first method I was suggested is to use*v.in.ply* and
then*r.report*, 
> but I have several issues: 
> - When I use *v.in.ply* I have this error: *ERROR: Wrong number
of 
> properties*. Is it a common error? How can I solve it? I have
attached a 
> part of my .ply file to this email so you can see how it  is
formatted. 
 
[Marion sent me an extract of the data offline] 
 
It seems that every data line in your .ply file has a trailing
white 
space at the end. This is counted as an extra property and explains
the 
message. When I erase these trailing white spaces, I don't get this 
error anymore. I don't know the format enough to know whether this is
an 
issue with v.in.ply not tolerating these white spaces, or an issue
with 
the program creating the .ply file which shouldn't add a white space
at 
the end. 
 
> - After importing my .ply file, I would like to use something
like 
> *r.report *to get the value of each point. However, I don't know
how to 
> convert my file into a format that this command will work with...
Could 
> you help me? 
 
r.report gives you a summary report about a raster, not a value by
point. 
 
Generally, if you want to cover an entire zone (your entire
open-pit 
mine, you will probably want to go the raster way. So, with the
points 
imported with v.in.ply, you could do something like the following: 
 
g.region vect=points res=1 -ap #set the xy extension of your raster
to 
the xy extension of the point cloud, and the resolution to 1 (you
have 
to adjust that depending on the size of your zone) 
v.surf.rst in=points out=mined_surface #interpolate a continous
height 
surface across the entire area 
r.volume mined_surface #calculate volume 
 
 
> 
> The second method I read about is *r.in.xyz*, but I don't know how
it 
> works, or what format of input I should use. Can I have more
information 
> about it? 
 
r.in.xyz is another option. It takes XYZ data and aggregates it by
pixel 
using a user-determined aggregation function. If you have a higher
point 
density than your target resolution, then you could use just the
data 
part of your .ply file, i.e. the part which has lines such as 
 
[...] 
97.08156 121.6752 99.27532 0 0 0 12 9 2 255 
97.08911 121.718 99.50104 0 0 0 46 40 24 255 
93.25124 115.0372 102.7768 0 0 0 62 53 20 255 
97.96031 123.8419 103.3994 0 0 0 150 184 211 255 
97.10852 121.6866 99.42679 0 0 0 9 9 0 255 
97.11196 121.7049 99.59032 0 0 0 19 12 4 255 
97.13282 121.688 99.43796 0 0 0 38 28 16 255 
97.17371 121.7129 99.41496 0 0 0 43 31 15 255 
97.1614 121.6344 99.27691 0 0 0 9 6 1 255 
[...] 
 
Knowing that there are 17 lines of other info at the top of the
extract 
you sent me, I could import the data using: 
 
r.in.xyz in=BROL/BascFin2-extrait.ply skip=17 out=xyz_mean
method=mean 
sep=space 
 
However, as the extent of the cloud is very large, but there are only
a 
few points, most of the pixels in the resulting raster are filled
with 
NULL values as there are no points falling within these pixels. 
 
Moritz</div>

<div class="gl_quoted"> </div>
</div>

mlennert · June 7, 2018, 7:56am

On 07/06/18 09:10, Moritz Lennert wrote:

Hi Marion,

Please keep the discussion on the list.

Am 7. Juni 2018 06:55:33 MESZ schrieb marion-brunet@sfr.fr:

Thank you very much for your answer! 
However, I have another ERROR when I use the command , even when
I  remove the white spaces. My command is: 
v.in.ply input=path\file.ply output=test 
and I get: 
 
AttributeError 
: 
'exceptions.UnicodeDecodeError' object has no attribute 
'value' 
 
I really don't know what it means..

I have the feeling that you provide us with only an extract of the message. Please provide the complete traceback and the exact command you used.

If you launch the command via the GUI you can find the history of commands in the console window (up arrow to see previous commands) or you can use the 'copy' button in the module GUI to copy the command line just before pushing run.

Sorry, on my phone I didn't see correctly that you actually provided the command.

But the traceback is still necessary.

Also which version of GRASS GIS are you using ? On which OS ?

Moritz