[GRASSLIST:5094] Re: General questions

Michael Ash mash at econs.umass.edu
Wed Nov 27 13:51:16 EST 2002

Disclaimer: I am a user, not a developer or expert.

> I have noticed that Grass is more oriented to raster
> processing.  Before going on I need to know whether is
> possible:
> - To create different kind of vector thematic maps based
> in nodes, lines, and polygons.

Yes, you can create thematic maps using d.vect and
d.vect.area.  The latter command allows you to specify fill
and line colors for vectors based on their category values.
The legend file lets you specify in some detail how each
category should be displayed.

> - To link vector entities with registers in a database
> (for example: a polygon representing a parcel with an ID
> to a register that has data like the name of the owner).

By juggling the category filenames in dig_cats/ in relation
to the vector geography files in dig/, dig_att/, and
dig_plus/, you can currently achieve this within GRASS that
is, without linking to a database.

There are also a suite of database commands (prefix db.)
that permit you to link to a database and use SQL.  I have
not been able to make these commands work BECAUSE I do not
have working ODBC on my linux computer and do not completely
understand the set-up). My understanding is that if ODBC is
working, then these commands work. (This responds to your
inquiry below, too.)

> - To query the database via SQL and see the results
> graphically in the monitor (for example: show all the
> parcels that meet a selection condition).

Finally, my understanding is that GRASS 5.1 (or the
production version thereof) will have much more by way of
vector and database communication built-in.

BTW, would it be possible for someone to explain to new
users, what will be available in 5.1?



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