[work] Re: [Qgis-user] No reference or details aboutthe "topological editiing" option in the documentation

[Matt Wilkie]

> On Wed, 2008-10-22 at 14:22 -0400, Woolard, Zachary S. wrote:
>> I just wanted to raise the point that you can set up topological
>> editing
>> in ESRI products. You can set up shared boundaries between polygons,
>> along with several other topology rules.  The only stipulation is that
>> the data be in a geodatabase.
>
> Just curious: was it always in ArcGIS (not ArcInfo) like that?

No not always. Topology enforcement was no longer available in the
transition from Arcinfo Workstation 7.x to ArcGIS 8 when the coverage
storage model was (attempted to be) abandoned. Topology rules were
re-introduced in 9.2 (may have been 9.1?) and continue to be further
developed now in 9.3+. There are two places to apply topology: real
topology which is enforced within the geodatabase and "map topology"
which is on the fly and saved within individual map projects (.mxd's).
The latter is simpler and limited, but occasionally useful when you
don't want or have the time to sit down and model your data properly.

A lot of us never understood, still don't, how ESRI could have ever
dropped topology in the first place. It's caused no end of headaches,
and still is. The new approach has a lot more potential, encompassing
a wider variety of rules and greater number of layers, but is harder
to utilize because you need to set it up ahead of time and it is
optional. With coverages you had no choice, topology is baked into the
file format.

I'm pleasantly surprised and encouraged to see topology has been
thought about and incorporated into qgis 1.0. :)

-- 
-matt