[GRASS5] Multiple attribute support in GRASS5.1:someconsiderations (long)

Radim Blazek Radim.Blazek at dhv.cz
Tue May 15 01:01:45 EDT 2001


Roger S. Miller wrote:
> "Eric G. Miller" wrote:
> > I think we all can agree GRASS has a ways to go on both attribute data
> > support *and* presentation.  Now, if for a vector "map", if each
> > layer/component (SITE, LABEL, LINE, AREA) has a separate attribute table
> > then wouldn't it be a simple matter to *allow* the user to define one
> > column of the table to indicate a "style" for the given thing.
>
> If I understand your suggestion, then what this would do is place
> database support for drawing attributes in some tagged-on external
> database (which is pretty much the way it works now) rather than in the
> database inherent in the GIS.  It provides yet another unintegrated
> capability for which a user will need separate training and for which
> the developers would have to provide separate support.  It's exactly
> what I would like to avoid.

Or we can say: developers will not spend any time on maitaining database 
because it is external and users do not need to learn new database 
system becase they can use system they know already.

> I know relatively little about database construction, so I can get over
> my head very quickly here.  What I envisioned is that the drawing
> attribute support would be invisible to the user, included in the same
> database structure that organizes and provides data on other
> attributes.  We don't currently have anything that uses that capability,
> so the structure wouldn't actually need to be filled.  It just needs to
> be there for later use.  If it's planned for, then it should be a
> relatively simple procedure to fill it with reasonable defaults.  The
> software to manipulate and use those attributes can come later.
>
> If it isn't planned in, then it will be relatively difficult to add it
> later.
>
>
> Roger Miller

I think that symbology of geographic data is usualy based on attributes
and dynamicaly created. Assigning color, style, width to graphic elements is 
good for CAD systems not for GIS. We work on data not on pictures.


Radim

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