[R-sig-Geo] RSAGA issues
Ludwig Hilger
l.hilger at ku.de
Mon Oct 29 16:18:23 CET 2012
Dear list,
TY for answering.
The first (Mr. Hurling) and the second (Input grids in the form of GRIDS =
"t_asp_class.sgrd;t_elev_class.sgrd" helped) issue are solved now.
I am still fighting with the resampling grid module and I have not found a
solution in the archives and got none on sourceforge. So here it is again,
hopefully explained a little better now:
1. When I resample a grid, I have to provide USER_YMIN, USER_XMIN, USER_XMAX
and USER_YMAX. Is there a way to automatically calculate these values from
the input DEM header and the cellsize selected for
resampling (as SAGA seems to do in the GUI)?
2. And if I copy the values from the SAGA GUI (after typing in the new
cellsize, the other four values in the GUI dialoge change), it is still not
working!
This code:
setwd("My working directory")
rsaga.geoprocessor(lib = "grid_tools", module = 0, param = list(INPUT =
"mydem.sgrd", GRID_GRID = "DEM_resampled.sgrd", KEEP_TYPE = TRUE, TARGET =
0, SCALE_UP_METHOD = 6, SCALE_DOWN_METHOD = 4,
USER_SIZE = res, # new cellsize read by scan(), eg 50
USER_XMIN = 24285, # should be automatically calculated from input file
header and new cellsize
USER_YMIN = 186945, # should be automatically calculated from input file
header and new cellsize
USER_YMAX = 197795, # should be automatically calculated from input file
header and new cellsize
USER_XMAX = 35835)) # should be automatically calculated from input file
header and new cellsize
gives:
Grid system: 10; 1158x 1086y; 24285x 186945y
Grid: DEM_2006-2010
Additional Grids: No objects
Additional Grids: No objects
Preserve Data Type: yes
Target Grid: user defined
[...] (rsaga.get.usage("grid_tools", 0))
error: executing module [Resampling]
Warnmeldung:
Ausführung von Kommando '"C:\Program Files
(x86)\SAGA-GIS_2.0.8/saga_cmd.exe" grid_tools 0 -INPUT
"D:/PROSA_Daten/ALS/ALS_2006-2010/DEM_2006-2010.sgrd" -GRID_GRID
"DEM_resampled.sgrd" -KEEP_TYPE -TARGET "0" -SCALE_UP_METHOD "6"
-SCALE_DOWN_METHOD "4" -USER_SIZE "50" -USER_XMIN "24285" -USER_YMIN
"186945" -USER_YMAX "197795" -USER_XMAX "35835"' ergab Status 1
Thank you again!
Ludwig
Rainer Hurling wrote
> On 26.10.2012 09:44 (UTC+2), Ludwig Hilger wrote:
>>
>> Dear list,
>>
>> I am comparatively new to RSAGA and have come across three problems I
>> have not been able solve by searching on the internet. Your help would
>> be very much appreciated. This is SAGA 2.0.8 and R 2.15.1.
>>
>> 1. Is there a way to access the header of a *.sgrd without having to
>> load the whole grid, i.e. not using read.sgrd()$header? I want to
>> determine the cellsize of a *.sgrd from within r for informational
>> purposes and I have 1 m grids with 62 km2.....
>
> The .sgrd file _is_ the header file of a SAGA GIS grid file. The grids
> data is in .sdat instead. You can read these very small header files
> (.sgrd) with several functions, for example
>
>
> hd <- readLines("filename.sgrd", n=-1)
>
> # split strings in names and values parts
> require(stringr)
> hd <- unlist(str_split(hd, "\t= "))
>
> # make a dataframe from the header data
> header <- data.frame(Parameter=hd[seq(1,length(hd),2)],
> Value=hd[seq(2,length(hd),2)])
>
> # The contents of such header is like that
> header
> # Parameter Value
> #1 NAME DGM5_saga
> #2 DESCRIPTION
> #3 UNIT
> #4 DATAFILE_OFFSET 0
> #5 DATAFORMAT FLOAT
> #6 BYTEORDER_BIG FALSE
> #7 POSITION_XMIN 3449220.0000000000
> #8 POSITION_YMIN 5487020.0000000000
> #9 CELLCOUNT_X 2907
> #10 CELLCOUNT_Y 6538
> #11 CELLSIZE 10.0000000000
> #12 Z_FACTOR 1.000000
> #13 NODATA_VALUE -99999.000000
> #14 TOPTOBOTTOM FALSE
>
>
> The other questions seem to be already answered on r-sig-geo and/or SAGA
> GIS discussion forum (
> http://sourceforge.net/p/saga-gis/discussion/790705/thread/77e3979c/ ).
>
> Hope this helps,
> Rainer
>
>
>> -------------------------------------------------------------------------------
>>
>>
>> 2. I have tried to call the Grid sum module in the following way:
>> rsaga.geoprocessor(
>> lib = “grid_calculus”,
>> module = 8,
>> param = list(
>> GRIDS = list(“t_elev_class.sgrd”, “t_asp_class.sgrd”),
>> RESULT = “t_codes”
>> )
>> )
>>
>> I get the following error, i.e. arguments of the function seem to get
>> mixed up:
>>
>> “library path: C:Program Files (x86)SAGA-GIS_2.0.8/modules
>> library name: grid_calculus
>> module name : Grids Sum
>> author : O. Conrad (c) 2010
>>
>> Load grid: t_codes...
>>
>> failed
>>
>> error: Grid file could not be opened.
>>
>> error: input file t_codes
>>
>> error: empty input list GRIDS
>> Usage: 8 -GRIDS -RESULT
>> -GRIDS: Grids
>> Grid list (input)
>> -RESULT: Sum
>> Grid (output)
>>
>> error: executing module Grids Sum
>> Warnmeldung:
>> Ausführung von Kommando '"C:Program Files
>> (x86)SAGA-GIS_2.0.8/saga_cmd.exe" grid_calculus 8 -GRIDS
>> "t_elev_class.sgrd" -RESULT "t_asp_class.sgrd" -GRIDS "t_codes"' ergab
>> Status 1”
>>
>> I have also tried c() instead of list() for the GRID-argument, I have
>> moeved GRID out of the param-list, etc. . In contrast,
>> rsaga.grid.calculus() works fine. I seem to have the same problem with
>> other modules as well, probably I do not provide the input grids in the
>> right way?
>>
>> -------------------------------------------------------------------------------
>>
>>
>> 3.
>> a) When I resample a grid, I have to provide USER_YMIN, USER_XMIN,
>> USER_XMAX and USER_YMAX. Is there a way to automatically calculate these
>> values from the input DEM header and the cellsize selected for
>> resampling (as SAGA seems to do in the GUI)?
>> b) If I want to use a target grid as a model for the new grid, where is
>> this to be specified? rsaga.get.usage("grid_tools", 0) gives me only the
>> options GRID_GRID and USER_GRID (which are output arguments according to
>> get.usage). There are no arguments for the path to the target grid.
>>
>> thank you,
>> Ludwig
>
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