[GRASS-user] r.denoise segfaults on a raster of 1166468401 cells

GRASS GRASS user
1

2012/12/15 <grass-user-request@lists.osgeo.org>

The following attempt segfaults on GRASS 6.4.3svn (nearly in the end of the
process, if I am not wrong), running on Core i7 with 32GB of RAM.

mdenoise ASTER GDEM2 over Greece

r.denoise in=aster_gdem2_ellas out=aster_gdem2_ellas_smoothed iterations=1
threshold=0.8 epsg=2100

The computational area comprises (Rows: 32401, Columns: 36001) 1166468401
cells. Is this too much?

Would (re-)running this on GRASS 7.0.svn make any difference?
I should better perform the process on a per (ASTER GDEM2) tile(s) basis,
shouldn’t I?

Hi Nikos. In my experience, utility works well with raster sizes no more than 2000x2000 (regardless of RAM size). That’s why the only way to denoise the large rasters — using of tiles and patching of final results.

Best regards,
Alexander.

2

Nikos:

> The following attempt segfaults on GRASS 6.4.3svn (nearly in the end of
> the process, if I am not wrong), running on Core i7 with 32GB of RAM.

> # mdenoise ASTER GDEM2 over Greece
> r.denoise in=aster_gdem2_ellas out=aster_gdem2_ellas_smoothed iterations=1
> threshold=0.8 epsg=2100

> The computational area comprises (Rows: 32401, Columns: 36001) 1166468401
> cells. Is this too much?

> Would (re-)running this on GRASS 7.0.svn make any difference?
> I should better perform the process on a per (ASTER GDEM2) tile(s) basis,
> shouldn't I?

Alexander Muriy:

Hi Nikos. In my experience, <mdenoise> utility works well with raster sizes
no more than 2000x2000 (regardless of RAM size). That's why the only way to
denoise the large rasters — using of tiles and patching of final results.

Of course! Yet, what about differently smoothed tile borders? Any additional
hints?

Nikos

3

Nikos:

> > The following attempt segfaults on GRASS 6.4.3svn (nearly in the end of
> > the process, if I am not wrong), running on Core i7 with 32GB of RAM.

> > # mdenoise ASTER GDEM2 over Greece
> > r.denoise in=aster_gdem2_ellas out=aster_gdem2_ellas_smoothed
> > iterations=1
> > threshold=0.8 epsg=2100

> > The computational area comprises (Rows: 32401, Columns: 36001)
> > 1166468401 cells. Is this too much?

> > Would (re-)running this on GRASS 7.0.svn make any difference?
> > I should better perform the process on a per (ASTER GDEM2) tile(s)
> > basis, shouldn't I?

Alexander Muriy:

> Hi Nikos. In my experience, <mdenoise> utility works well with raster
> sizes no more than 2000x2000 (regardless of RAM size). That's why the only
> way to denoise the large rasters — using of tiles and patching of final
> results.

Nikos:

Of course! Yet, what about differently smoothed tile borders? Any
additional hints?

For the records, there is a statement by John A Stevenson, "Re: [GRASS-user]
New addon: r.denoise. Denoise topography including SRTM," e-mail on the grass-
user list on 17. 09. 2009:

--%<---
Xianfang also recommended denoising small areas, perhaps with overlap,
and seeing how well they can be merged.
--->%--

Nikos