[GRASS-user] denoising error (r.denoise)

[Nikos Alexandris]

Helmut Kudrnovsky wrote:

> hi,

Hallo Helmut :-)

(Thank you so, very, much for your time!).  Few comments below.

> what I've tested here on my win7-64bit-box with osgeo4w-wingrass6.4.3.svn:
> 
> as stated in the manual
> http://trac.osgeo.org/grass/browser/grass-addons/grass6/raster/r.denoise/des
> cription.html
> 
> (1)
> wget http://www.cs.cf.ac.uk/meshfiltering/index_files/Doc/mdsource.zip
> unzip mdsource.zip
> cd mdenoise
> 
> (2) built mdenoise within the osgeo4w-stack
> 
> g++ -o mdenoise mdenoise.cpp triangle.c
> 
> (3) and put the exe in the %PATH%
> (e.g. C:\Users\xxxxxxx\AppData\Roaming\GRASS6\addons)
> 
> (4) projected location (epsg3035) with the Aster DEM v2 (~30m x ~30m)
> 
> (5)
> 
> g.region -p
> projection: 99 (Lambert Azimuthal Equal Area)
> zone:       0
> datum:      etrs89
> ellipsoid:  grs80
> north:      2686202.52683254
> south:      2627115.59422961
> west:       4471032.62800725
> east:       4541841.53570558
> nsres:      22.717006
> ewres:      22.717006
> rows:       2601
> cols:       3117
> cells:      8107317
> 
> r.denoise --verbose input=aster24myrisel at PERMANENT
> output=aster24myriseldenoise Exporting points...
> Denoising...
> Input File: C:\grassdata/alpslaeaepsg3035/testrmdenoise/.tmp/10536.0.xyz
> Neighbourhood: Common Vertex
> Threshold: 0.930000
> n1: 5
> n2: 50
> Read Model...
> Triangulation...
>     93.789 seconds
> Denoising Model...
> Error malloc:  Out of memory.

I think that this is, indeed, a (lack of enough) memory issue.  On linux, with 
32GB of RAM of course, denoising 20+ tiles was no problem.

 
> (6)
> 
> g.region -p -a rast=aster24myrisel at PERMANENT vect=smallisel at testrmdenoise
> align=aster24myrisel at PERMANENT projection: 99 (Lambert Azimuthal Equal
> Area)
> zone:       0
> datum:      etrs89
> ellipsoid:  grs80
> north:      2657420.08023204
> south:      2642086.10118283
> west:       4497043.5998759
> east:       4515580.67677094
> nsres:      22.717006
> ewres:      22.717006
> rows:       675
> cols:       816
> cells:      550800
> 
> r.denoise --verbose input=aster24myrisel at PERMANENT
> output=aster24myriseldenoise Exporting points...
> Denoising...
> Input File: C:\grassdata/alpslaeaepsg3035/testrmdenoise/.tmp/10656.0.xyz
> Neighbourhood: Common Vertex
> Threshold: 0.930000
> n1: 5
> n2: 50
> Read Model...
> Triangulation...
>      5.148 seconds
> Denoising Model...    11.232 seconds
> Saving Model...     1.295 seconds
> Reloading data...
> command finished
> 
> => IIUC mdenoise is very memory consuming, so adjust the region to a
> reasonable "small" extent.

See above -- it worked out looping over many individual ASTER GDEM2 tiles.

> as mentionded in the manual, the location should be projected.
> geographic (lat-long) location requires projection during processing which
> I've never got to run.

Right -- the module wont run if you set a geographic ref. system.  No problem, 
even from inside a WGS84 location.  Setting a proper EPSG code refering to a 
projected reference system is all that is required.

Best, Nikos
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