[GRASSLIST:328] Re: How can I do for getting a lake's area?

[H Bowman]

note d.what.vect reports area statistics as well; has anyone compared the
answers from that with that of:
r.report units=me
r.stats -a
?
(for a suitably high resolution raster of course)


Additionally, there is r.surf.area for 3D (instead of plan) surface
areas which may be more useful for steep terrain, but introduces the
fractal problem and apparently suffers from underreporting edge data as
well.

there is r.volume to look at as well.


Hamish



> of course you can do that. You just have to digitize the lakeborder or
> get it from another source (e.g. arial photo) and export it to a
> raster map.  with the help of r.report you'll get the area of the
> lake. to spare computing time I would mask the area out. i'm not quite
> shure if v.area does the trick for vector maps.
> >  
> > I want  to calculate one lake's yearly area change at the time scale
> > which may be from 1980 to now. ( Ibnur Lake which located 
> > approximately in E82, E84, N44, N46, in China's Uighur Autonomous
> > Region). And my problem is,
> >   1. Can I do this job by using GRASS?
> >   2. If so, is there any free GIS data(?) on the Internet that I can
> >   use for my purpose to calculate the lake's area?
> >   3. If there are, what the process I will follow to get this work
> >   out?