[GRASS5] grass5.1 directories proposal

Eric G . Miller egm2 at jps.net
Thu Jan 4 02:09:57 EST 2001

On Thu, Jan 04, 2001 at 11:49:06AM +0700, Justin Hickey wrote:
> > Proposal:
> >  - the number of import/export modules scripts needs to be heavily 
> > reduced.
> >    At time there are 92 tools for import/export/tape analysis...
> > 
> >  - Idea: The raster database structure should be changed to the G3D
> >    structure: all files related to a raster map should go into one
> >    directory. Currently many files are spreaded in many directories.
> >    An example for the G3D data structure can be found here:
> >    http://www.geog.uni-hannover.de/grass/grid3d/index.html (sample 
> >    dataset)
> I can't really comment on this one since I am not familiar with G3D, but
> from a directory management point of view, it sounds good.

There might be other benefits to using the g3d format.  It uses a tile
based system which is (a) more likely to compress better than an entire
row [less variability]; (b) for fp data random seeks/reads/writes
for cells aren't really supported/possible due to keeping separate NULL
file in sync; and (c) is more efficient for high
resolution display and is easier to generalize to current cell

The library code for modules would have to make this transition
transparent and would have to be able to emulate the row based access
methods unless we want to rewrite every raster and imagery module!  The
inefficiency of translating tile access to row access could be
substantial (writes would seem most difficult since some kind of caching
may be needed).

Eric G. Miller <egm2 at jps.net>

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