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I'm very new on GRASS and trying to extract the viewshed of a SRTM HGT file.

This is what I've done so far: (why I'm using GRASS command line this way is not in question. Please answer this same way)

grass --exec r.in.srtm -1 --overwrite input=S23W044.hgt

grass --exec g.list type=raster

grass --exec g.region raster=S23W044 -p

grass --exec r.viewshed input=S23W044 output=S23W044-shed coordinates=-43.5,-22.5

But I can't find my output file and don't know it format.

GRASS GIS 7.5.svn

  • To simplify your life you can gather all commands in a single script file, set file permission to "executable" and then run it all with --exec yourscript.sh|bat – markusN Apr 30 '18 at 14:16
  • I will code a Java program to execute these tasks. Thanks anyway. – Magno C May 1 '18 at 2:55
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Figured out with

grass --exec r.out.gdal in=S23W044-shed output=elevation.tif createopt="PROFILE=GeoTIFF,TFW=YES"

but it came with no data...don't know if it was because some r.viewshed incorrect parameter.

** EDIT ** : Actualy it don't came empty. The default behaviour of r.viewshed is to produce a 0/1 map being 0=can't see and 1=can see.

I must add the -e parameter to get the elevation value for what I can see and null for what I can't see.

All is working now.

  • You are using GRASS in some non-standard way. Can you explain what is grass --exec? Without understanding this syntax, I don't see how to help. Please first start a normal GRASS session, and run your commands to make sure that all the steps work. – Micha Apr 30 '18 at 11:40
  • By using grass --exec I can execute grass commands without invoke GRASS environment. I need my bash available to do some other tasks. I don't want to work inside a normal grass session. – Magno C May 1 '18 at 2:57

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