[GRASS-user] r.terraflow problem

[Markus Metz]

Aleksey Naumovwrote:
>
> Thank you for your help. At least I figured out why r.terraflow would not
> run at all - I had both stats.out and stats.out.old sitting on my hard disk
> from some time before. As I understand now, r.terraflow creates a backup of
> the runtime statistics file (by default, stats.out.old), and if this backup
> file already exists, it simply refuses to remove it and bails out.

It should say why it bails out, maybe file a ticket in trac?
>
> I thought that r.terraflow scales better to larger DEMs than r.watershed,
> but I'll try r.watershed next.

It's more or less on par now when using the disk swap mode of
r.watershed. In theory, r.terraflow should scale better with very
little memory and very large files, e.g. billions of cells and less
than 512 MB memory (untested, speculating, similar speed with 2GB and
500 million cells). The temporary files of r.watershed are much
smaller than those of r.terraflow, this can make a crucial difference
without large file support.
>
> As far as updating grass, this version (GRASS 6.4.0svn-7) is the latest
> available via OSGeo4W.

The error mentioned below has been fixed recently (2 weeks ago), maybe
the OSGeo4W version is older.

What other options do I have on WinXP (a Cygwin-based
> install?)?

Get a nightly built installer from here

http://josef.fsv.cvut.cz/wingrass/grass64/

or compile yourself the latest svn snapshot from source.

> Assertion failed: nrows * ncols == str->stream_len(), file
> grass2str.h, line 144

That one was fixed two weeks ago.

Markus M

>
> Markus Metz wrote:
>>
>> Aleksey Naumov wrote:
>> > Dear GRASS users,
>> >
>> > I am trying to run r.terraflow in GRASS 6.4.0svn (GIS library revision:
>> > 37101 (2009-05-10)) provided as part of the OSGeo4W bundle on WinXP. The
>> > command prints some output, which looks normal, and then exits right
>> > away
>> > without doing anything.
>> >
>> > Here is the command and the output I get:
>> >
>> > (Thu Jul 29 13:32:43
>> > 2010)
>> > r.terraflow --overwrite --verbose elevation=dem at PERMANENT filled=tf_dem
>> > direction=tf_fdir swatershed=tf_sink accumulation=tf_fac tci=tf_tci
>> > STREAM_DIR=C:/Active_projects/tmp/tf
>> > cell dem header compatible with region header
>> > stats.out: File exists
>> > Elevation stored as FLOAT (4B)
>> > Region size is 13000 x 9200
>>
>> This is 119.6 million cells, too large for wingrass, r.terraflow will
>> most likely abort because the temporary files become too large (no
>> large file support in wingrass). Try r.watershed instead.
>>
>> > STREAM temporary files in C:/Active_projects/tmp/tf  (THESE
>> > INTERMEDIATE STREAMS WILL NOT BE DELETED IN CASE OF ABNORMAL
>> > TERMINATION OF THE PROGRAM. TO SAVE SPACE PLEASE DELETE
>> > THESE FILES MANUALLY!)
>> > file stats.out exists - renaming.
>>
>> Either manually delete the file stats.out first before running
>> r.terraflow or, as suggested in the other reply, update grass.
>>
>> Markus M
>
>