Mon, Jul 24 2006
13:36:36
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Request created by guest
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Subject: r.in.gdal, AAIGrid: FCELL is forced on output
Platform: GNU/Linux/x86
grass obtained from: CVS
grass binary for platform: Compiled from Sources
GRASS Version: 2006.07.23
If the input AAIGrid raster is double floating point, r.in.gdal will import it
as a trunctated FCELL anyway.
to reproduce:
create a DCELL map, eg.:
r.mapcalc 'map=double(rand(100.0,1000.0))'
export and import it back:
r.out.gdal input=map format=AAIGrid type=Float32 output=map.arc
r.in.gdal input=/home/shoofi/map.arc output=map_gdal
see the difference (ie. data corruption):
r.mapcalc 'diff=map-map_gdal'
r.info -r diff
min=-0.000031
max=0.000031
Note that the integer/floating point detection for AAIGrid driver in GDAL was
fixed after 1.3.2 release, so we could consider disposing r.out/in.arc in Grass
7 *if* r.in.gdal is fixed to support DCELL for AAIGrid (r.in.arc allows enforcing
DCELL output, maybe r.in.gdal should follow?).
Maciek
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Mon, Jul 24 2006
14:48:18
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Mail sent by msieczka
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> If the input AAIGrid raster is double floating point, r.in.gdal will import
> it as a trunctated FCELL anyway.
UPDATE:
This problem is not limited to AAIGrid! Eg. GeoTiff is affected to. This is a
serious issue! What r.out.gdal exports should be identical to what r.in.gdal
imports, but it's not.
Maciek
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Mon, Jul 24 2006
14:48:56
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Mail sent by msieczka
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> If the input AAIGrid raster is double floating point, r.in.gdal will import
> it as a trunctated FCELL anyway.
UPDATE:
This problem is not limited to AAIGrid! Eg. GeoTiff is affected to. This is a
serious issue! What r.out.gdal exports should be identical to what r.in.gdal
imports back, but it's not.
Maciek
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Mon, Jul 24 2006
14:50:05
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Subject changed to r.in.gdal: FCELL is forced on output by msieczka
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Mon, Jul 24 2006
15:12:41
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Comments added by guest
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I have confirmed that r.in.gdal imports double precision (Float64) data
as FCELL_TYPE instead of DCELL_TYPE. I'm not sure why this was done.
I'll look into fixing this, though it might not be wise to put this into
6.1 final.
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Mon, Jul 24 2006
15:24:46
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Taken by fwarmerdam
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Mon, Jul 24 2006
15:24:46
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Comments added by fwarmerdam
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