Dear GRASS Users Mailing List,
I would like to ask some advice on using GRASS to map the output of weather-driven population models for ecosystem analysis.
Our group is considering GRASS as a way to map the georeferenced output of the ecosystem models developed in our lab. In short, once meteorological data (i.e., model input) and geographic data are acquired for a particular landscape, an ecosystem model is run for each weather station location of interest. Therefore, the output of the model consists of a summary table combining the point locations of the weather stations with the output value of interest.
In order for this output to be mapped, an interpolation process is needed to retrieve the spatial distribution of the values estimated by the ecological model across the landscape. Another critical point is the ability to 'clip' and eliminate areas which are not of interest to the study, such as elevation which is too high, or other tracts of land or water which are not of interest to the study.
Would GRASS be able to interpolate such spatial distribution and also 'clip' the out-of-interest areas? I am new to GRASS but I assume that such capabilities are, at least potentially, already in place in GRASS. What I cannot figure out is the amount of work needed to implement such functionalities starting from the summary output table that I mentioned above. Any hint is appreciated.
Kind regards,
Luigi Ponti
Visiting Scholar
University of California, Berkeley
Environmental Science, Policy & Management
lponti@nature.berkeley.edu
Hi Luigi,
I'm currently working on something similar (hydrological model grass embedded) and I think the easiest way is to write some shell script doing what you need.
I think You should:
- read the file and generate a point feature (cat filename | v.in.ascii .....) maybe by using also awk for formatting your file...
- interpolate your points with one of the already existing modules (v.surf.rast, v.idw) and generate your raster
- then using map algebra (r.mapcalc) for set null the values of cell above your max height (r.mapcalc 'final_map=if(dem>1500,interp_map,null())' )
I think it will be pretty easy to implement if you know some basis of shell programming....
Hope this could be useful.
Maxi
Luigi Ponti wrote:
Dear GRASS Users Mailing List,
I would like to ask some advice on using GRASS to map the output of weather-driven population models for ecosystem analysis.
Our group is considering GRASS as a way to map the georeferenced output of the ecosystem models developed in our lab. In short, once meteorological data (i.e., model input) and geographic data are acquired for a particular landscape, an ecosystem model is run for each weather station location of interest. Therefore, the output of the model consists of a summary table combining the point locations of the weather stations with the output value of interest.
In order for this output to be mapped, an interpolation process is needed to retrieve the spatial distribution of the values estimated by the ecological model across the landscape. Another critical point is the ability to 'clip' and eliminate areas which are not of interest to the study, such as elevation which is too high, or other tracts of land or water which are not of interest to the study.
Would GRASS be able to interpolate such spatial distribution and also 'clip' the out-of-interest areas? I am new to GRASS but I assume that such capabilities are, at least potentially, already in place in GRASS. What I cannot figure out is the amount of work needed to implement such functionalities starting from the summary output table that I mentioned above. Any hint is appreciated.
Kind regards,
Luigi Ponti
Visiting Scholar
University of California, Berkeley
Environmental Science, Policy & Management
lponti@nature.berkeley.edu
--
Eng. Massimiliano Cannata
Scuola Universitaria Professionale della Svizzera Italiana
Istituto Scienze della Terra
Via Trevano, c.p. 72
CH-6952 Canobbio-Lugano
Tel: +41 (0)58 666 62 18
Fax +41 (0)58 666 62 09
I think this type of thing is very straight forward in GRASS. It is
one of the reasons I have started using GRASS instead of ArcGIS. It is
very easy to write a shell script (or Python or Perl, etc) to perform
a run of your model, convert the model output to GRASS format,
post-process the output and build visualizations. I do this for wave
and sediment transport models and there are many other disciplines
represented by people on this mailing list.
The interpolation and "masking" of irrelevant data is a key strength
of GIS in general and something that is trivial in GRASS. (usually
only a few GRASS commands depending on how sophisticated your good/bad
data criteria is).
David
On 10/13/05, Luigi Ponti <lponti@infinito.it> wrote:
Dear GRASS Users Mailing List,
I would like to ask some advice on using GRASS to map the output of
weather-driven population models for ecosystem analysis.
Our group is considering GRASS as a way to map the georeferenced output
of the ecosystem models developed in our lab. In short, once
meteorological data (i.e., model input) and geographic data are acquired
for a particular landscape, an ecosystem model is run for each weather
station location of interest. Therefore, the output of the model
consists of a summary table combining the point locations of the weather
stations with the output value of interest.
In order for this output to be mapped, an interpolation process is
needed to retrieve the spatial distribution of the values estimated by
the ecological model across the landscape. Another critical point is the
ability to 'clip' and eliminate areas which are not of interest to the
study, such as elevation which is too high, or other tracts of land or
water which are not of interest to the study.
Would GRASS be able to interpolate such spatial distribution and also
'clip' the out-of-interest areas? I am new to GRASS but I assume that
such capabilities are, at least potentially, already in place in GRASS.
What I cannot figure out is the amount of work needed to implement such
functionalities starting from the summary output table that I mentioned
above. Any hint is appreciated.
Kind regards,
Luigi Ponti
Visiting Scholar
University of California, Berkeley
Environmental Science, Policy & Management
lponti@nature.berkeley.edu
--
David Finlayson
Marine Geology & Geophysics
School of Oceanography
Box 357940
University of Washington
Seattle, WA 98195-7940
USA
Office: Marine Sciences Building, Room 112
Phone: (206) 616-9407
Web: http://students.washington.edu/dfinlays
I would second David's comments. GRASS does these kinds of analyses easily within shell & Perl scripts, which I have setup to run routinely. Please email me if you want any concrete examples.
Regards,
Tom
David Finlayson wrote:
I think this type of thing is very straight forward in GRASS. It is
one of the reasons I have started using GRASS instead of ArcGIS. It is
very easy to write a shell script (or Python or Perl, etc) to perform
a run of your model, convert the model output to GRASS format,
post-process the output and build visualizations. I do this for wave
and sediment transport models and there are many other disciplines
represented by people on this mailing list.
The interpolation and "masking" of irrelevant data is a key strength
of GIS in general and something that is trivial in GRASS. (usually
only a few GRASS commands depending on how sophisticated your good/bad
data criteria is).
David
On 10/13/05, Luigi Ponti <lponti@infinito.it> wrote:
Dear GRASS Users Mailing List,
I would like to ask some advice on using GRASS to map the output of
weather-driven population models for ecosystem analysis.
Our group is considering GRASS as a way to map the georeferenced output
of the ecosystem models developed in our lab. In short, once
meteorological data (i.e., model input) and geographic data are acquired
for a particular landscape, an ecosystem model is run for each weather
station location of interest. Therefore, the output of the model
consists of a summary table combining the point locations of the weather
stations with the output value of interest.
In order for this output to be mapped, an interpolation process is
needed to retrieve the spatial distribution of the values estimated by
the ecological model across the landscape. Another critical point is the
ability to 'clip' and eliminate areas which are not of interest to the
study, such as elevation which is too high, or other tracts of land or
water which are not of interest to the study.
Would GRASS be able to interpolate such spatial distribution and also
'clip' the out-of-interest areas? I am new to GRASS but I assume that
such capabilities are, at least potentially, already in place in GRASS.
What I cannot figure out is the amount of work needed to implement such
functionalities starting from the summary output table that I mentioned
above. Any hint is appreciated.
Kind regards,
Luigi Ponti
Visiting Scholar
University of California, Berkeley
Environmental Science, Policy & Management
lponti@nature.berkeley.edu
--
David Finlayson
Marine Geology & Geophysics
School of Oceanography
Box 357940
University of Washington
Seattle, WA 98195-7940
USA
Office: Marine Sciences Building, Room 112
Phone: (206) 616-9407
Web: http://students.washington.edu/dfinlays
--
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177
EMAIL: thomas.adams@noaa.gov
VOICE: 937-383-0528
FAX: 937-383-0033