[GRASS-dev] [bug #4438] (grass) export of AAIGrid and arc incorrect

this bug's URL: http://intevation.de/rt/webrt?serial_num=4438
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Subject: export of AAIGrid and arc incorrect

Platform: GNU/Linux/x86
grass binary for platform: Compiled from Sources
GRASS Version: cvs 08.05.2006

Hello,

concerning the export of AAIGrid (r.out.gdal) and ArcInfo Ascii Grid
(r.out.arc) an incorrect output occurs if the nsres/ewres in GRASS is not
equal - AAIGrid/arc stores only one value for res.

The difference between the resolutions is (in my case) small (3-> decimal
place) hence the incorrect export is only visible if high numbers of row/col
exist (high resolution imagery/covering continental scales).

The remedy is to resample the image to an equal nsres ewres. The problem is
located in the data format and not GRASS so I would suggest to either

1. prompt a warning if nsres != ewres

or

2. do an automatic resampling with equal nsres/ewres with an info prompt

otherwise the exported files have a wrong geolocation.

regards, Martin

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