[Qgis-user] Interpolation with breaklines

[nicolas.cadieux at archeotec.ca]

Hi,

Have you tried the interpolation plugin in QGis? 
(raster/interpolation/interpolation) if the plugin is activated.  I see 
the option is available for points, structure lines and  break lines.... 
It seems to work if you have  a z field.  If you are using a tach or a 
total station, you will probably not have too many points for this plugin.

Nicolas

Le 2015-11-20 09:40, Neumann, Andreas a écrit :
>
> Hi,
>
> No - the points are manually surveyed - field work - very precise 
> surveys with Tachymeter. It is in developed areas where walls outside 
> of buildings are quite frequent.
>
> We also have LIDAR data (quite dense from last year) - but they are 
> not precise enough for certain projects that require accuracies at 
> plus/minus 5cm and contour line intervals at 20-30 cm.
>
> I will try converting the break lines into dense points - to reach a 
> similar effect than normal break lines.
>
> Andreas
>
> On 2015-11-20 14:57, Nicolas Cadieux wrote:
>
>> Hi again,
>>
>> Are the irregular points LIDAR? If it is comparable in point density, 
>> you could do two interpolations. One for the ground that could use a 
>> larger interpolation search window and then one for the objects that 
>> are above the ground with a very small search window (like 1m). After 
>> that,  you could make a normalized DEM and then you can add the walls 
>> to the ground model..   That would give you sharp walls feature on a 
>> smooth ground DEM.
>>
>> The PDAL library or Cloud Compare could separate buildings from the 
>> ground.
>>
>> Good luck!
>>
>> Nicolas Cadieux M.Sc.
>> Les Entreprises Archéotec inc.
>> 8548, rue Saint-Denis Montréal H2P 2H2
>> Téléphone: 514.381.5112  Fax: 514.381.4995
>> www.archeotec.ca
>>
>> On Nov 20, 2015 5:47 AM, "Neumann, Andreas [via OSGeo.org] " <[hidden 
>> email]> wrote:
>>
>>     Hi,
>>
>>     At my workplace we have to generate terrain models (contour
>>     lines) from irregularly input points with heights. We also have
>>     break lines (e.g. walls) that we would like to take into account
>>     during interpolation.
>>
>>     While there are quite a few interpolation available in GRASS or
>>     SAGA, I can't find any interpolation methods that also take break
>>     lines.
>>
>>     I found http://grasswiki.osgeo.org/wiki/TIN_with_breaklines -
>>     which seems to do what I want, but is a separate module and
>>     builds on a "triangle" executable and is not distributed with GRASS.
>>
>>     I have therefore two questions:
>>
>>     1. Is this the only FOSSGIS option we have, if breaklines should
>>     be considerered during interpolation? Or are there alternatives?
>>
>>     2. Did someone use v.traingle. this in a production environment?
>>     Does it work properly? I am just asking before I try to install it.
>>
>>     3. If this works fine - can we try to distribute it with OSGeo4W?
>>
>>     Thanks,
>>
>>     Andreas
>>
>>
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