[GRASS-user] interpolation from massive vector point input

Hi,

I get a text file from a hydromorphological model which includes
an massive amount of geographical points with attributes (velocity,depth,..),
which I input using v.in.ascii (around 120000 points).
The points are located in a river (20 m widht) in a resolution of
appr. 20x20 cm,
but this is not fixed and depending on their location within in the river
(points in the outer bends show rougher resolution then points in the
inner bends).
So these points are not regularly (in the sense of raster map) distributed.

Anyway I want to generate a raster surface (resolution = appr. 0.25)
from the vector points attributes, e.g a surface of velocity and one
for depth.
Additionally to the vector points there is a line vector indicating
the shore line
of the river (depth=0 and velocity = 0).

Now I am looking for a method for interpolation of these points. I
found v.surf.icw
which would take into account that there is a shoreline which is not overflown
by the water (interpolates within the river). But it is not recommended for such
massive data point input. Is there any other recommendable way fur such
a purpose (considering the shore line and that there is 0 velocity and
0 depth on land?

Any suggestions are welcome!

Thank you,

/johannes

Johannes,
what about first generating a tin with breaklines (=your shoreline)
running a Delaunay constrained triangulation :

http://grass.osgeo.org/wiki/TIN_with_breaklines

then output a raster from this tin ?

(just a suggestion, I never used/tested v.triangle AddOnn)

Vincent.

Le lundi 27 août 2012 à 11:58 +0200, Johannes Radinger a écrit :

Hi,

I get a text file from a hydromorphological model which includes
an massive amount of geographical points with attributes (velocity,depth,..),
which I input using v.in.ascii (around 120000 points).
The points are located in a river (20 m widht) in a resolution of
appr. 20x20 cm,
but this is not fixed and depending on their location within in the river
(points in the outer bends show rougher resolution then points in the
inner bends).
So these points are not regularly (in the sense of raster map) distributed.

Anyway I want to generate a raster surface (resolution = appr. 0.25)
from the vector points attributes, e.g a surface of velocity and one
for depth.
Additionally to the vector points there is a line vector indicating
the shore line
of the river (depth=0 and velocity = 0).

Now I am looking for a method for interpolation of these points. I
found v.surf.icw
which would take into account that there is a shoreline which is not overflown
by the water (interpolates within the river). But it is not recommended for such
massive data point input. Is there any other recommendable way fur such
a purpose (considering the shore line and that there is 0 velocity and
0 depth on land?

Any suggestions are welcome!

Thank you,

/johannes
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Hi Johannes,

On Mon, Aug 27, 2012 at 11:58 AM, Johannes Radinger <johannesradinger@gmail.com> wrote:

Hi,

I get a text file from a hydromorphological model which includes
an massive amount of geographical points with attributes (velocity,depth,…),
which I input using v.in.ascii (around 120000 points).
The points are located in a river (20 m widht) in a resolution of
appr. 20x20 cm,
but this is not fixed and depending on their location within in the river
(points in the outer bends show rougher resolution then points in the
inner bends).
So these points are not regularly (in the sense of raster map) distributed.

Anyway I want to generate a raster surface (resolution = appr. 0.25)
from the vector points attributes, e.g a surface of velocity and one
for depth.
Additionally to the vector points there is a line vector indicating
the shore line
of the river (depth=0 and velocity = 0).

Now I am looking for a method for interpolation of these points. I
found v.surf.icw
which would take into account that there is a shoreline which is not overflown
by the water (interpolates within the river). But it is not recommended for such
massive data point input. Is there any other recommendable way fur such
a purpose (considering the shore line and that there is 0 velocity and
0 depth on land?

Any suggestions are welcome!

Consider also v.surf.rst
http://grass.osgeo.org/grass70/manuals/html70_user/v.surf.rst.html
See also http://grass.osgeo.org/wiki/RST_Spline_Surfaces

ciao


Dr. Margherita Di Leo

On 27/08/2012 12:58, Johannes Radinger wrote:

Hi,

I get a text file from a hydromorphological model which includes
an massive amount of geographical points with attributes (velocity,depth,..),
which I input using v.in.ascii (around 120000 points).
The points are located in a river (20 m widht) in a resolution of
appr. 20x20 cm,
but this is not fixed and depending on their location within in the river
(points in the outer bends show rougher resolution then points in the
inner bends).
So these points are not regularly (in the sense of raster map) distributed.

Anyway I want to generate a raster surface (resolution = appr. 0.25)
from the vector points attributes, e.g a surface of velocity and one
for depth.
Additionally to the vector points there is a line vector indicating
the shore line
of the river (depth=0 and velocity = 0).

I would use the shoreline to create a polygon of the river area. THen convert that polygon to a raster, and use it as a MASK. Once the MASK is in place, the interpolation will work only on the area of the river.
And as Madi suggested, try v.surf.rst.

Now I am looking for a method for interpolation of these points. I
found v.surf.icw
which would take into account that there is a shoreline which is not overflown
by the water (interpolates within the river). But it is not recommended for such
massive data point input. Is there any other recommendable way fur such
a purpose (considering the shore line and that there is 0 velocity and
0 depth on land?

Any suggestions are welcome!

Thank you,

/johannes
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