Hi all,
since there are almost two (or more?) open threads about converting
site data to raster data I had find another subject and I fear, that
my problem is located between my two ears.
My location has a resolution of 25km in x znd y direction. I have
imported site (satllite track) data with a along track resolution of
appr. 600m. I want to convert them to raster data but not do an
interpolation with s.surf.* or something like that. Preferable is a
'drop-in-a-bucket' approach which calculates a mean from all site data
within every cell. AFAIK s.to.rast uses the last value 'dropping' into
a cell. Is there a way in GRASS to calculate the (block)-mean and then
use s.to.rast, or did I miss something, or have I use for instance
GMT's blockmean and pipe my data into s.to.rast?
Regards,
Stephan
--
----------------------------------------------------------------------
Stephan Eickschen Tel. : +49 (0)8153 28-1351
GeoForschungsZentrum Potsdam (GFZ) Fax. : +49 (0)8153 28-1207
Department 1, Section 1.2
c/o email: eicksch@gfz-potsdam.de
DLR Oberpfaffenhofen www : http://op.gfz-potsdam.de
Box 1116
82234 Wessling
Germany
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Hello
On Thu, 10 Apr 2003, Stephan Eickschen wrote:
Hi all,
appr. 600m. I want to convert them to raster data but not do an
interpolation with s.surf.* or something like that. Preferable is a
'drop-in-a-bucket' approach which calculates a mean from all site data
within every cell. AFAIK s.to.rast uses the last value 'dropping' into
You could try the latest CVS version of s.surf.idw with the npoints option
set to 1. Then if more than one site falls into a cell it will average
them. Assuming there will be some cells with no sites falling into them
and you want them to be null (s.surf.idw will assign the value of the
nearest site) you could use the output of s.to.rast as a mask as it will
have nulls where no sites fell within the cells.
e.g.
g.copy rast=storastoutput,MASK
r.resample input=ssurfidwoutput output=newoutput
g.remove rast=MASK
or something like that. I haven't thought it through fully but it might do
what you're looking for.
Paul
Paul,
thanks for your suggestion. Just one question:
You could try the latest CVS version of s.surf.idw with the npoints option
set to 1.
How recent should the update be? I build GRASS (GRASS-5.0.2-cvs [Jan 2003])
on april 1st... The man page still tells me about that the last value
is taken ('no warning'). Is the man page outdated or have I to rebuild
GRASS?
Stephan
--
----------------------------------------------------------------------
Stephan Eickschen Tel. : +49 (0)8153 28-1351
GeoForschungsZentrum Potsdam (GFZ) Fax. : +49 (0)8153 28-1207
Department 1, Section 1.2
c/o email: eicksch@gfz-potsdam.de
DLR Oberpfaffenhofen www : http://op.gfz-potsdam.de
Box 1116
82234 Wessling
Germany
----------------------------------------------------------------------
Hello Stephan
On Thu, 10 Apr 2003, Stephan Eickschen wrote:
Paul,
thanks for your suggestion. Just one question:
> You could try the latest CVS version of s.surf.idw with the npoints option
> set to 1.
How recent should the update be? I build GRASS (GRASS-5.0.2-cvs [Jan 2003])
on april 1st... The man page still tells me about that the last value
After 30th March should be all right; I don't know what's wrong there...
The changed main.c from src/sites/s.surf.idw/cmd is here
http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass/src/sites/s.surf.idw/cmd/main.c
and the updated man page is at
http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass/html/html/s.surf.idw.html
If your s.surf.idw has the '-n' flag then it is the latest one (e.g. type
's.surf.idw help' to see the options). Perhaps the man pages aren't
updated unless you do a full make (but you said you did... I don't know).
Paul