r.patch results in a blank map in GRASS

Question

I have a collection of tiles downloaded from the EDINA Digimap service, in asc format. I imported these into GRASS using the r.in.gdal function, and they appear in the display screen as expected.

I want to join these separate raster files together to create one continuous raster, however when I use the r.patch function, a map is created in the layer manager, and I get 100% completion, but nothing shows up in the display.

Any ideas how to correct this? Or a different function that is better suited?

Answer 1

One suggestion would be to ensure that the computational region is correctly set, i.e.:

g.region rast=tile1,tile2,tile3,...,tilen -p

Then you should run the r.patch command:

r.patch input=tile1,tile2,tile3,...,tilen output=merged_raster

You should be able to display the merged raster in your GRASS monitor. If it is still blank, try passing -z to r.patch. Further details about the function here