[GRASS-user] vector maps - help needed - part 2

[Hamish]

> > sorry, but I still don't understand the vector/database handling of 
> > grass completely. At the moment I use dbf files, but this seems not
> > to be very flexible.

try sqlite

> > I think no because I have
> > an other folder on my computer which is called "vector" but what are
> > the files "cidx,coor,dvln,head,hist,topo"?

see
 http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass6/doc/vector/vector.html?rev=HEAD&content-type=text/html
 http://freegis.org/cgi-bin/viewcvs.cgi/grass6/doc/vector/


> > As you can see, I'm really confused, what this database stuff is 
> > for when all data is still stored somewhere else.

it's for attributes (road name, surface type, etc.). Actual coordinates
and topology are stored in $MAPSET/vector/

The two are linked by category number.
 
> > I hope that somebody can help me and explain me the idea of 
> > vector/database handling.
> 
> v.in.ogr, as well as many other Grass modules that output a new vector
> layer, will setup categories for features and upload them into a key
> "CAT" column (it could be any other name though, see v.db.connect)
> along with their attributes respectively.
> 
> Read your grass-6.1.cvs/docs/html/vectorintro.html too.

also
 http://grass.itc.it/grass61/manuals/html61_user/databaseintro.html
 http://grass.itc.it/grass61/manuals/html61_user/sql.html
 http://grass.itc.it/grass57/tutorial/links.html


> I hope it helps.

ditto


Hamish