[GRASS5] [bug #3961] (grass) d.zoom: always alligns to resolution = data corruption

Request Tracker grass-bugs at intevation.de
Wed Jan 4 17:04:57 EST 2006

this bug's URL: http://intevation.de/rt/webrt?serial_num=3961

Subject: d.zoom: always alligns to resolution = data corruption

Platform: GNU/Linux/i386
grass obtained from: CVS
grass binary for platform: Compiled from Sources
GRASS Version: 2005.11.16

When you d.zoom on a raster where data cells are not alligned to the resolution (eg. usually ArcInfo rasters, SRTM tiles), your resulting region gets alligned to the current resolution value instead of the cell borders. This causes serious problems, examples:

1. r.to.vect output is shifted from cell's center
2. r.mapcalc 'copy=map' actually doesn't produce an exact copy, but it's shifted version
3. reprojecting with r.proj will lead to wrong (shifted) results

This looks to me like a data corruption issue. I wonder how many people out there are corrupting their data not knowing it.

For more info refer to http://grass.itc.it/pipermail/grassuser/2005-December/031624.html and friends.


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