[Qgis-user] Interpolation with breaklines
nicolas.cadieux at archeotec.ca
nicolas.cadieux at archeotec.ca
Fri Nov 20 07:45:41 PST 2015
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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