[GRASS5] line types

[Radim Blazek]

On Monday 08 April 2002 06:07 pm, rgrmill at rt66.com wrote:

In general, I think that we need to distinguish lines and boundaries.

> Folks,
>
> GRASS "types" vector objects as lines, area edges and points.  Is there
> any useful purpose to distinguishing between lines and area edges?  I
> haven't tested recently, but I seem to recall that the topology has
> nothing to do with that distinction; area edges don't necessarily make
> areas, lines can enclose areas and v.support/v.build don't retype lines
> based on the actual topology.

Lines can enclose areas? What do you mean? That grass type LINE can
be area edge? No, it can't, areas are build only form AREA type.

> I ask because I tracked some problems back to the difference between
> lines and area edges:
>
> v.llabel (from pre2) does not label lines if they are "typed" as area
> edges.

OK, problem in module, not in LINE/BOUNDARY types existence.
That is problem of many modules that are missing boundary option.
In grass51 are options: point,line,boundary,centroid,area.
If type 'area edge' is missing in some modules, it is not yet reason to merge
LINE/BOUNDARY types.

> Generally it looks like the distinction between lines and area edges is
> useless and that it causes more problems then it helps.  Is it
> reasonable to start removing that distinction from the GRASS modules?
>
> Roger Miller

How do you want to remove distinction?. Replace all  "if (Line->type == 
LINE)" by  "if (Line->type == LINE ||  Line->type == AREA )
or merge  LINE and AREA types in the vector library?

I think that LINE/AREA distinction should be keept and boundary
(area edge) option should be add to modules 'type' option.

Radim