[Qgis-user] Interpolation with breaklines

[Neumann, Andreas]

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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