[GRASS5] REMINDER: LZW code to be unhooked this Saturday

[Eric G . Miller]

Just wanted to remind everyone that, Saturday, I plan to go forward with
changing the default build set-up to use the DEFLATE code instead of LZW
code for compressing FP rasters and G3D files.  I don't plan to remove
the LZW code just yet, but this change *will* break the reading of all
existing FP rasters that are also compressed. If you need to revert for
some reason, just uncomment the USE_LZW_COMPRESSION define in:
libes/gis/put_row.c, libes/gis/get_row.c, libes/g3d/fpcompress.c

The simple solution to do before "upgrading":

	Run r.compress -u on all floating point raster data.

The less tested after the fact solution:

	Get and build the r.lzw2z script and run it on all of your
	FP raster data. (http://www.jps.net/egm2/r.lzw2z.tgz).

You will immediately know there's a problem if you don't do this, since
any attempt to read an LZW compressed raster will generate an error
like:

ERROR: Failed to read row[n]

(that's not the exact message, but close enough).

NOTE: CELL rasters are *not* affected by this modification.

For G3D files where the user specified LZW (which is not the default),
you will have to dump the data using r3.out.ascii *before* upgrading.
There is currently no after the fact method.

I will try to find the appropriate file in the top level directory to
make a shouting statement about this incompatible (but unfortunately
required) change.

(grasslist: Effects code in CVS only)
-- 
Eric G. Miller <egm2 at jps.net>

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