[GRASSLIST:1383] Re: why r.report gives wrong figured area data?

[Hamish]

> After these I entered command "r.report" for each map and see the
> results.
> It goes very pretty and gives me following results.
> 
> For map2 (2001.09.25): 1/lake area...0.623 km^2
> For map1 (2002.10.30): 1/lake area...0.928 km^2
> For map3 (2003.05.25): 1/lake area...1.125 km^2
> 
> But the problem is the results were much smaller than the real area.
> The real area of this lake was changed from 500km2 to 1200km2 in these
> 5 years.
> So my question is: why r.report gives me the wrong figured area data?


may I suggest making sure all the map is in view, either by viewing it
with 'd.rast' and then zooming with 'd.zoom' or 'g.region'.

g.region rast=map_name
will zoom to the extent of the map, and to the map's resolution.

Also try using 'd.barscale' to make sure the map scale it correct.

If you used v.digit to mark the outline of the lake you could use
'd.what.vect' to query the area too.



good luck,
Hamish