Important change information for GRASS 5.0 beta1..10 users
This text is intended to GRASS 5.0 beta1..10 users who upgrade to
the 5.0.0 stable release.
[This will affect all GRASS 5 versions later than beta10 (CVS was updated
Jan 18 2001)]
Because of the UNISYS patent (http://www.unisys.com/unisys/lzw/) on
the LZW compression algorithm, on January 18 2001, GRASS 5 library code no
longer uses this method to compress floating point rasters and G3D files.
Unfortunately, this creates an incompatible change for persons using earlier
versions of GRASS 5.0 (beta1 to beta10 is affected).
Note: This does NOT affect
How to migrate your GRASS 5 floating point raster maps:
- Before installing newer GRASS libraries and binaries (beta11 and
later) you must uncompress all floating point raster maps.
Again: In order to make your data readable you must uncompress all
floating point rasters before installing newer GRASS libraries and
binaries. The command "r.compress -u" will do the job (see below for a
script to assist).
- After installing the
new binaries you may recompress your rasters with "r.compress" which will
use the DEFLATE method available in libz (this compression
library is usually installed by default on your system).
How to migrate your GRASS 5 G3D raster voxel maps:
- Unfortunately, any LZW compressed G3D files must be dumped with
r3.out.ascii, and then reimported with r3.in.ascii.
The GRASS 5.0 Development Team apologizes for this inconvenience.
We provide two ways to convert your data:
Two-step conversion: Requires old and new GRASS.
That's it. Welcome to the patent-free GRASS 5.
One-step conversion: Does not require old GRASS, simply run in new
GRASS 5beta11 (or later):
r.lzw2z changes the compression on-the-fly within the new
GRASS 5.0beta11 (or later):
Jan 18 2001, GRASS Development Team, last update:
$Date: 2002-10-30 11:14:17 +0000 (Wed, 30 Oct 2002) $