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In QGIS (2.18), I have several raster files (.asc-format) that have no projection information. The images display well at EPSG:5677. My aim is to store all the files in a new folder, using the GeoTIFF format and assigning EPSG:5677.

I have no python experience, however some python coding could help me here, I guess. I read something similar but shapefile-related here: Exporting several files at same time in QGIS?

Of course, this doesn't work with my raster files. So here goes my question: how can I export a bunch of raster files, using the original file names and assigning the desired coordinate reference system without having to export every single file manually?

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yenats
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    Do you have ArcGIS? Also, if you have experience in R, I would suggest a very simple workaround. – Vijay Ramesh Mar 08 '17 at 16:30
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    No, I don't have ArcGIS. I wouldn't call myself experienced in R, but I do use it from time to time. However, I've never worked with geodata in R. – yenats Mar 08 '17 at 16:32
  • I have provided a solution in R, since you mentioned that you use it from time to time. Let me know if that helps. It's much quicker than doing it manually in QGIS. – Vijay Ramesh Mar 08 '17 at 16:52
  • Possible duplicate of http://gis.stackexchange.com/questions/208617/convert-batch-file-using-gdal-translate (which was closed as off-topic, but has answers). – AndreJ Mar 09 '17 at 14:38
  • Related: https://stackoverflow.com/questions/49919166/batch-process-multiple-ascii-to-raster-files-in-r – Tung Mar 22 '22 at 15:51

2 Answers2

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Based on the User's comment that they would be open to trying this in R, here's the solution:

#Load the three packages below 
library(sp)
library(raster)
library(rgdal)

#List the files that you want to export from the source folder
files <- list.files(path="C:\\Users\\.", pattern="asc$", full.names=TRUE) #selects all the asc files in the directory
s <- stack(files) # stack all of them using r raster library
proj4string(s) <- CRS("+init=epsg:5677") #Sets it to the projection you wanted
newname<-paste("C:\\Users\\",names(s)) #Saves the previous names
writeRaster(s,newname, bylayer=T, format="GTiff")#Edited based on Fumy's comment
Vijay Ramesh
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  • Thank you, this worked for me. However, I preferred to keep the original file names, so I specified the location by

    newname<-paste("C:\Users\",names(s))

    and then stored the files

    writeRaster(s,newname, bylayer=T, format="GTiff")

     – yenats Mar 09 '17 at 11:36
  • Thanks @F.Fumy. That's a great suggestion. Updated it to reflect your edits. – Vijay Ramesh Mar 09 '17 at 14:15
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Given that you have QGIS, you therefore also have GDAL installed on your machine. So I suggest you adapt the example in this post over on Stackexchange and create a batch file.

In your case, you will also want to set the gdal_translate a_srs switch to 5677 and change the -of switch (see documentation). So the relevant line in the batch file will be something like this:

gdal_translate -of "GTiff" -a_srs 5677 %mypath%!infile! %mypath%!outfile!

If you leave out the -of switch altogether, it will default to GeoTiff anyway. I just wanted to differentiate from the example given in the link. If you do not have an environment variable set for gdal_translate (which in a standard osgeo4w installation probably won't be the case) then you will have to run this command from the osgeo4w bin folder (in my case c:\osgeo4w64\bin).

MappaGnosis
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  • I guess it should be GTiff instead of GTif, should not it? (on edit version May 23'17, accessed June 15'18) – Santosa Sandy Jun 15 '18 at 11:45
  • Indeed. On this point it is worth noting a small change since I gave this answer originally and that is that GTiff is no longer the default here and GDAL will guess the format based on the extension. – MappaGnosis Jun 19 '18 at 07:12