[GRASSLIST:652] Extracting vector river network from r.terraflow.

[Antonio G. - Geotronix]

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HI.

After trying r.flow and r.watershed to compute river networks over my
DEM I've finally tried r.terraflow with the 28/06 snapshot.
r.terraflow is finally giving a better stream network than the former
and this is visible by the flow accumulation raster layers.
However, what I need is a vector river network layer. I presume I have
to use the flow accumulation layer provided by r.terraflow as input but
I don't know how to process it. Must I use r.thin + r.line. But how? I
gave it a try but got errors from r.line:

GRASS:~ > r.line input=r.tf-7m-thin-accu output=v.tf-7m-thin-accu
Opening files
Performing extraction
update_list:  crowded cell 8H (89,321)
ERROR: cell file is not thinned properly.
       Please run r.thin

Maybe I have to reclass the categories?

BTW. The flow accumulation categories should express the amount of 
water running through a cell? I saw the categories are rather 
large 0 --> 631571. But what are they exacly expressing. If I get 
a value of 631000 for a cell of a accumulation layer outputted by 
r.terraflow, how must I interpret it?

Thanks
Bye
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