RSAGA .asc morphology loop question
Hi Tim, the rsaga.esri.wrapper currently expects the in.* and out.* arguments (with the ASCII/float ESRI grids) to have NO file extension - the file extension to be used for all ESRI grids can be given by the esri.extension argument; it currently defaults to ".asc" when format="ascii" and to ".flt" when format="binary". (Sorry that the help file is not explicit enough regarding the file extensions; will add this to the next update.) Two more remarks on your code: > read.ascii.grid(i) This simply reads the grid but does nothing else - redundant. > prec=1 Slope is calculated in radians (see ?rsaga.slope). So with a 0.1 radian increment (the smallest increment that can be represented with prec=1 digits) you get 0.1 * 180 / pi = 5.7 degree increments on the degree scale - you probably want to haver a finer discretization. I would recommend prec=3 in the case of slope (and probably prec=6 or 7 for curvature attributes). I hope this helps. Cheers Alex
Tim Sippel wrote:
I'm using RSAGA (version 0.9-4) to calculate rate of change (slope) on a
series of .asc files. I'm getting en error message saying it can't open the
grid. My code follows:
library(RSAGA)
# data directory containing my .asc files to calculate slope on
wd.in<-"C:\\my.data.dir"
setwd(wd.in)
env<-rsaga.env(path="C:\\programs\\saga_vc", cmd="saga_cmd.exe")
asc.list<-dir(wd.in, pattern='.asc$')
for (i in asc.list) {
read.ascii.grid(i)
rsaga.esri.wrapper(fun=rsaga.slope, in.dem=i, method="maxslope",
in.esri=T, out.esri=T, clean.up=T,
out.slope=c(paste("SLOPE",as.character(i),sep="")), env=env,
esri.workspace=wd.in, format="ascii", georef="corner", prec=1)
}
Here are some of the data files in my directory from my asc.list object
above:
asc.list
[1] "tmp1_220E-15N2005-03-02.asc" "tmp10_220E-15N2005-05-13.asc"
"tmp100_220E-15N2007-05-13.asc" "tmp101_220E-15N2007-05-21.asc"
[5] "tmp102_220E-15N2007-05-29.asc" "tmp103_220E-15N2007-06-06.asc"
"tmp104_220E-15N2007-06-14.asc" "tmp105_220E-15N2007-06-22.asc"
The error I'm getting is below:
SAGA CMD 2.0.3
library path: C:\programs\saga_vc/modules
library name: ta_morphometry
module name : Local Morphometry
author : (c) 2001 by O.Conrad
Load grid: tmp1_220E-15N2005-03-02.asc...
failed
error: Grid file could not be opened.
error: input file [tmp1_220E-15N2005-03-02.asc]
error: executing module [Local Morphometry]
Not sure what I've done wrong in calling in the grid files and would
appreciate advice.
Best regards,
Tim Sippel
University of Auckland
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Alexander Brenning brenning at uwaterloo.ca - T +1-519-888-4567 ext 35783 Department of Geography and Environmental Management University of Waterloo 200 University Ave. W - Waterloo, ON - Canada N2L 3G1 http://www.fes.uwaterloo.ca/geography/faculty/brenning/