Load multiple raster in the cell spatial grid

[Etienne DELAY]

Hi again, 

I have created a grid from my DEM. Now I would like to populate this same grid with other values (from other raster). How can I do that ? Is there any model in the library to take a look ?

E.

[Patrick Taillandier]

Hi,

The simplest way is to use asc files for the other grid files and to read them as matrices. Please find attached an example.

Cheers,

Patrick

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[Etienne DELAY]

What the hardest way ? Because it's always something horrible to deal with asc ...

E.

Le jeudi 20 juillet 2017 14:11:41 UTC, Patrick Taillandier a écrit :

Hi,

The simplest way is to use asc files for the other grid files and to read them as matrices. Please find attached an example.

Cheers,

Patrick

2017-07-20 15:33 GMT+02:00 Etienne DELAY <abce...@gmail.com>:

Hi again, 

I have created a grid from my DEM. Now I would like to populate this same grid with other values (from other raster). How can I do that ? Is there any model in the library to take a look ?

E.

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[Patrick Taillandier]

Hi,

I do not understand why it is horrible to deal with asc file (that are just ascii matrices with a header - QGIS is very good to translate geotiff to asc), but a very bad way to deal with your problem with using only geotiff is to define a grid per geotiff file.....you can after transfer the attribute of each cell of each grid to the main grid.

Cheers,

Patrick  

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[Etienne DELAY]

In fact Qgis is not good enough ! After a reprojection our grid is  not more a regular grid (cells are rectangular)... and gdal_translate, sometimes overpast :-S

E.

--

Cordialement

Etienne DELAY

[Etienne DELAY]

Hi, 

I have used GRASS-GIS in R to "build" all my ASC needed ! Load data as a matrix with your script work like a charm :-)

If someone needs an example, my script is : 

library(rgrass7)

## remove (almost) everything in the working environment.

## You will get no warning, so don't do this unless you are really sure.

rm(list = ls())

# initialisation of grass data base 

initGRASS(gisBase = "/usr/lib/grass72", home = tempdir(),

          gisDbase = "/home/user/Documents/futurSahel/grassDB/",

          location = "gama_transform", mapset = "PERMANENT", override=TRUE)

execGRASS("g.list", parameters = list(type = "raster")) ##list all reaster in GrassDB

#########################################################################

## resampling

#########################################################################

execGRASS("g.region", parameters = list(res = "50000", vector="square"))

##liste of NDVI/MODIS raster

my.pattern <- "A2016*"

rast.div.l <- attr(execGRASS("g.list", parameters = list(type = "raster", pattern = my.pattern)),"resOut") ## get a raster list from location mapset

for(i in 1:length(rast.div.l)){

  execGRASS("r.resamp.stats", parameters = list(input=paste0(rast.div.l[i]),

                                                output = paste0("resamp_",rast.div.l[i]),

                                                method="mode"),

            flags = c("overwrite","w")) ## resample with resolution

}

## Comput dem 

execGRASS("r.resamp.stats", parameters = list(input="dem_resemple50",

                                              output = "resamp_dem",

                                              method="mode"),

          flags = c("overwrite","w")) ## resample with resolution

#########################################################################

## 

my.pattern <- "resamp_*"

rast.div.l <- attr(execGRASS("g.list", parameters = list(type = "raster", pattern = my.pattern)),"resOut") ## get a raster list from location mapset

for(i in 1:length(rast.div.l)){

  execGRASS("r.out.ascii",parameters = list(input=paste0(rast.div.l[i]),

                                            output = paste0("/home/user/gama_workspace/BestModel/includes/dem/",rast.div.l[i],".asc"),

                                            precision=4),

            flags = c("overwrite"))

}

[Patrick Taillandier]

Hi,

Just to say that I have implemented a way to simply import multiple raster files into a grid: grid cell files: [dem_file,land_cover_file] ;

I have added an example model in the model library: Features/Data Importation/Multiple Raster File Import.gaml.

Cheers,

Patrick

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[Etienne DELAY]

Nice ! I will try for the LiENs challenge :-p

E.