[GRASS-user] change the precision of elevation data

GRASS GRASS user
1

Hello list!

I have 10x10 meter cell sized, 1 meter precision elevation data, but I have to create a contour map that features 0.5 meter steps
hence the current level of precision is insufficient. Can I do this with grass gis?

I tried the fallowing command, but I didnt get what I want, beacouse it create the .5 meter countours as the .0 meter countours 10 meter buffered line.

r.contour input=ddm-10 output=contour_05 step=0.5 cut=0

Thanks:

Balázs

2

Hello Balázs,

what is the raster base size setting of your region?
maybe the cell size are too big for the 0.5m parameter.

András

2011.02.07. 14:18:05 dátumon Balázs Szabó szabobaa@gmail.com írta:

Hello list!

I have 10x10 meter cell sized, 1 meter precision elevation data, but I have to create a contour map that features 0.5 meter steps
hence the current level of precision is insufficient. Can I do this with grass gis?

I tried the fallowing command, but I didnt get what I want, beacouse it create the .5 meter countours as the .0 meter countours 10 meter buffered line.

r.contour input=ddm-10 output=contour_05 step=0.5 cut=0

Thanks:

Balázs

–

Bödőcs András, PhD
ELTE Régészettudományi Intézet
Térinformatika Labor

Budapest, H-1088
Múzeum krt. 4/b.
T: +36-1-4116554, +36-1-4855200/2910
F: +36-1-4116553
E-mail: bodocs.andras@btk.elte.hu
www: http://www.regeszettudomany.hu

3

Hello list!

I have 10x10 meter cell sized, 1 meter precision elevation data, but I have to create a contour map that features 0.5 meter steps
hence the current level of precision is insufficient. Can I do this with grass gis?

I tried the fallowing command, but I didnt get what I want, beacouse it create the .5 meter countours as the .0 meter countours 10 meter buffered line.

r.contour input=ddm-10 output=contour_05 step=0.5 cut=0

Does the raster have integer values or floats?
try r.info -t ddm-10

If it’s a CELL type, then do:
r.mapcalc ddm-10_float=1.0*ddm-10
to create an equivalent floating point raster.

Then rerun the r.contour command

··· 
-- 
Micha Silver
[http://www.surfaces.co.il/](http://www.surfaces.co.il/)
Arava Development Co.  +972-52-3665918
4

Thanks yours responses!

I have integer values instead float.
So I used tha command as Micha suggested
r.mapcalc ‘ddm10_float = float(ddm)’

Balazs

  1. február 7. 14:28 Bödőcs András írta, <bodocs.andras@btk.elte.hu>:

Hello Balázs,

what is the raster base size setting of your region?
maybe the cell size are too big for the 0.5m parameter.

András

2011.02.07. 14:18:05 dátumon Balázs Szabó <szabobaa@gmail.com> írta:

Hello list!

I have 10x10 meter cell sized, 1 meter precision elevation data, but I have to create a contour map that features 0.5 meter steps
hence the current level of precision is insufficient. Can I do this with grass gis?

I tried the fallowing command, but I didnt get what I want, beacouse it create the .5 meter countours as the .0 meter countours 10 meter buffered line.

r.contour input=ddm-10 output=contour_05 step=0.5 cut=0

Thanks:

Balázs

–

Bödőcs András, PhD
ELTE Régészettudományi Intézet
Térinformatika Labor

Budapest, H-1088
Múzeum krt. 4/b.
T: +36-1-4116554, +36-1-4855200/2910
F: +36-1-4116553
E-mail: bodocs.andras@btk.elte.hu
www: http://www.regeszettudomany.hu

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