[R-sig-Geo] Slope and Aspect calculations in R

[Tomislav Hengl]

Yes: SAGA runs normally on Linux (I use it also), but you can not use the command line from R (i.e.
RSAGA) to pass command to SAGA  :(

But you can use R to pass command lines to SAGA without RSAGA (i.e. the batch files):

http://saga-gis.wiki.sourceforge.net/Executing+Modules+with+SAGA+CMD 

Tom Hengl
http://spatial-analyst.net 


> -----Original Message-----
> From: Thomas Adams [mailto:Thomas.Adams at noaa.gov]
> Sent: Friday, July 10, 2009 4:20 PM
> To: Tomislav Hengl
> Cc: r-sig-geo at stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] Slope and Aspect calculations in R
> 
> Tom,
> 
> Thanks! I have seen your posts and results of some of your work with
> SAGA and I am very interested. But, I have been to lazy to this point to
> try compiling SAGA for either MacOS X or Linux (is a Linux distribution
> available?).
> 
> Regards,
> Tom
> 
> Tomislav Hengl wrote:
> > Dear Josh, Thomas,
> >
> > I typically use R+SAGA (R on top!) for such type of analysis (and I do have access to all
> operating
> > system/software). There must be some good reasons that I am using SAGA (speed, stability, rich
> > geomorphometry module etc.)! So do not give up so easy on SAGA.
> >
> > I especially like that SAGA is fairly efficient in processing big grids, and the commands are
> rather
> > compact. For example to reproject grids from one to another proj4string, you only need to set
> e.g.:
> >
> >
> >> rsaga.geoprocessor(lib="pj_proj4", 2, param=list(SOURCE_PROJ=paste('"', proj4string(dem25m),
> '"',
> >>
> > sep=""), TARGET_PROJ="\"+proj=longlat +datum=WGS84\"", SOURCE="TWI.sgrd", TARGET="TWI_ll.sgrd",
> > TARGET_TYPE=0, INTERPOLATION=0))
> >
> > *see http://www.geomorphometry.org/R.asp
> >
> > I remember that somebody did manage to set-up SAGA also under Mac OS
> > (http://www.saga-gis.uni-goettingen.de/html/index.php?module=pnForum&func=viewtopic&topic=458),
> but
> > I also remember that most of students on our GEOSTAT course used Windows under Mac OS to run
> SAGA. I
> > am sure that it should be possible to compile SAGA under Mac OS, but somebody needs to put some
> > effort to bridge this gap (check also with Olaf Conrad).
> >
> > Here is more discussion about the same topic from few months ago:
> > https://stat.ethz.ch/pipermail/r-sig-geo/2009-April/005418.html
> >
> > cheers,
> >
> > Tom Hengl
> >
> >
> >
> >> -----Original Message-----
> >> From: r-sig-geo-bounces at stat.math.ethz.ch [mailto:r-sig-geo-bounces at stat.math.ethz.ch] On
> Behalf
> >> Of Thomas Adams
> >> Sent: Friday, July 10, 2009 3:12 PM
> >> To: Josh London
> >> Cc: r-sig-geo at stat.math.ethz.ch
> >> Subject: Re: [R-sig-Geo] Slope and Aspect calculations in R
> >>
> >> Josh,
> >>
> >> I use R & GRASS together on both MacOS X and Linux without problems.
> >> It's very direct to write a shell script that calls both R & GRASS
> >> within a single script. Writing a R script that calls GRASS may be more
> >> tedious to do what you want. Writing a shell script that calls both may
> >> be the wat to go.
> >>
> >> Tom
> >>
> >> Josh London wrote:
> >>
> >>> Thanks for the suggestions so far regarding the use of GRASS or SAGA.
> >>>
> >>> We have considered those options but SAGA doesn't appear available for
> >>> MacOS. My understanding is that spgrass6 is more for accessing R
> >>> code/functions from within GRASS vs accessing GRASS functions from
> >>> within R. We have all our other analysis coded up in R, and just need
> >>> these functions to do one part of a bigger process. Maybe I'm
> >>> misunderstanding how to use R and GRASS together. I'll do some further
> >>> research.
> >>>
> >>> Thanks again
> >>> Josh
> >>>
> >>> Josh London wrote:
> >>>
> >>>> Hello
> >>>>
> >>>> We are looking to mimic, in R, the slope (max magnitude difference
> >>>> between a cell and its neighbors) and aspect (direction of maximum
> >>>> magnitude difference) functions found in ESRI's Spatial Analyst
> >>>> package. We were just about to code up the slope function but thought
> >>>> I would make sure we weren't re-inventing any wheels already out there.
> >>>>
> >>>> Thanks
> >>>> Josh
> >>>>
> >>>>
> >> --
> >> Thomas E Adams
> >> National Weather Service
> >> Ohio River Forecast Center
> >> 1901 South State Route 134
> >> Wilmington, OH 45177
> >>
> >> EMAIL:	thomas.adams at noaa.gov
> >>
> >> VOICE:	937-383-0528
> >> FAX:	937-383-0033
> >>
> >> _______________________________________________
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> >> R-sig-Geo at stat.math.ethz.ch
> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >>
> >
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> >
> 
> 
> --
> Thomas E Adams
> National Weather Service
> Ohio River Forecast Center
> 1901 South State Route 134
> Wilmington, OH 45177
> 
> EMAIL:	thomas.adams at noaa.gov
> 
> VOICE:	937-383-0528
> FAX:	937-383-0033