Can anyone help me convert the image in NetCDF format to Geotiff with R?
Hi Hendrik and Mohammad,
I was not able to convert a netcdf file opened by open.ncdf() to raster as described by Hendrik above. The reason being that raster() requires the filename, not a netcdf connection.
A netcdf file can be opened directly in raster() and then subsequently written to a geotiff using writeRaster(). For example like this example using downloaded bathymetry data from GEBCO:
------
library(ncdf)
library(raster)
## Reading netcdf file
gebco2014
Hello Mr. Layelmam,
Here is the way I open netcdf with R:
# opening package 'ncdf'. This is a package to read, write and/or create netCDF files.
# Very good informations about R and netcdf are avaiable here: http://www.image.ucar.edu/GSP/Software/Netcdf/
### program start, load packages
install.packages("ncdf") # only necessary if not already installed
install.packages("raster") # only necessary if not already installed
library(ncdf) # load package in R-script
library(raster)
############
# now open your working directory
setwd() # within the brackets the path to your working directory
# Import of a netcdf-file. The order 'file.choose()' will open a window where one can search for the right file
Test_ncdf = open.ncdf(file.choose())
print(Test_ncdf) # get some information about this file e.g. the relevant variables
# now convert netcdf to raster
rast
Hi Hendrik and Mohammad,
I was not able to convert a netcdf file opened by open.ncdf() to raster as described by Hendrik above. The reason being that raster() requires the filename, not a netcdf connection.
A netcdf file can be opened directly in raster() and then subsequently written to a geotiff using writeRaster(). For example like this example using downloaded bathymetry data from GEBCO:
------
library(ncdf)
library(raster)
## Reading netcdf file
gebco2014
Another option is creating a rasterbrick:
###
### might need to download ncdf4 online ###
library(ncdf4)
library(raster)
fname
Dear Mohammed
I use the following code for R:
#*************************************************************
# Export NetCDF file to TIFF: Single or Multiple File
#*************************************************************
library(ncdf4)
library(raster)
#Working directory
PATH="D:/NNR/"
setwd(PATH)
INTO="air.mon.mean.nc"
OUTO="air.tif"
nc
Hi,
I find the reading more straightforward with the following:
library(rgdal)
library(raster)
nc
You can use gdal => sudo apt install gdal-bin
gdal_translate -of GTiff -a_srs EPSG:4326 input.nc output.tif
Luis Morales-Salinas Thanks alot for the script. I have benefited from it verbatim
Luis Morales-Salinas Thanks alot for the script. I have benefited from it verbatim
Just wanted to add that as Guilherme Marting said, a simple gdal_translate can really work well. Now, you have to make sure that your NetCDF file has not curvilinear coordinates but lonlat. Otherwise the conversion works but is not georeferenced adequately (each pixel = 1º).
You can use the CDO command to cope with this :
cdo -setgrid,grid.txt input.nc input_lonlat.nc
gdal_translate -of GTiff -a_srs EPSG:4326 NETCDF:input_lonlat.nc:var output.tif
The grid.txt file must have such structure, examples are given in between [ ] :
gridtype = lonlat
gridsize = xsize*ysize [28800]
xname = lon
xlongname = longitude
xunits = degrees_east
yname = lat
ylongname = latitude
yunits = degrees_north
xsize = nbr_X_points [160]
ysize = nbr_Y_points [180]
xfirst = x_sw_corner (float, in degrees) [1.2]
xinc = float (in degrees) [0.15]
yfirst = y_sw_corner (float, in degrees) [-45.6]
yinc = float (in degrees) [0.15]
How can I convert multiple ncdf4 files to respective multiple raster files? I am unable to do that.
Thanks
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