[GRASS-user] What output from r.topidx?

[Rich Shepard]

   Following the example on the r.topidx man page I ran the two following
commands:

r.mapcalc "house_elev = if (isnull(aberDEM), aberDEM, house_catchment)"

r.topidx in=house_elev out=house_tci

   I can find no output. house_tci does not display in a monitor, running
r.stats -Anc house_tci out=house_stats
produced an empty file, and so did
r.reports house_tci

   What have I missed here that I find no output at tall?

Rich