"Raster map not found" error using GRASS r.walk

Question

I'm using GRASS' r.walk for the first time, and I'm trying calculate the best path between two different points. I have a DEM (from SRTM) and a slope map derived from that same DEM. Both are in the same directory, and I'm running it via command line.

The command is pretty simple, but I'm getting an error I'm not sure how to troubleshoot.

R.walk elevation=cut_n30e000.tif friction=Slope_Italy_Greece.tif output=pathing start_coordinates=36.440683,28.216723 stop_coordinates=36.195597,27.964125

I get the following from running the command:

Walking costs are a=0.72 b=6 c=1.9998 d=-1.9998

Lambda is 1

Slope_factor is -0.2125

ERROR: Raster map <cut_n30e000.tif> not found

What do I do about that error? How is it "not found"? It's in the same directory.

Answer 1

All GRASS modules work with maps that have been either imported into the GRASS database, or referred to by the r.external command (saves disk space).

For the first option you would do:

r.import input=cut_n30e000.tif output=cut_n30e000

For the second option:

r.external input=cut_n30e000.tif output=cut_n30e000

You might want to have a look at the following wiki pages:

GRASS Intro

Importing data into GRASS