Stefan,
> > > PS: ...of course there was a reason why Radius Topology is that
> > > successfull (in terms of sales)
>
> > Can you explain why you say this?
>
> mhm... I think radius topology is a successful product because it
> ensures that people don't add invalid geometries to datasets. So, its
> nice to have such a tool from a manager perspective, although it should
> not really be necessary from an educational perspective.
Radius Topology:
1. Guarantees that invalid geometries are not added to a dataset because if
they fail Oracle validation Radius won't process them. ("Garbage in" will not
produce anything good!).
2. If a valid geometry is provided then it will try and construct shared
topological primitives from it. This does not always work even if the geometry
is itself OK: mainly a problem with polygon data.
3. The construction of shared topological primitives uses a basic "rule" engine
that is up to the management/administration team to design and get right. It is
akin to creating a data model of a database and then generating a schema from
it. Simple to say, harder to do (and so a lot don't). No other topology product
has a rule" engine capability.
4. Allows construction of a network (node/edge) or planar (node/edge/face)
topological space (manifold) using the same data structures and based on
SDO_GEOMETRY and not SDO_TOPO making it accessible to existing GIS applications
that can already work with Oracle Spatial.
5. Is client independence.
6. Provides a topological manifold full of shared primitives that can be used
to analyse data, produce new views or products, and produce faster queries etc.
However, one can only do this with 100% confidence of the result, if 100% of
the data in a dataset has had topological primitives constructed from it. See
last sentence in point 2.
> Or am I wrong about a) its success, b) its function?
> (Btw. I have never used it myself)
1Spatial have sold quiet a few copies of RT (at least as far as I know). But
how many I don't know. What defines commercial success?
The ones I personally have had dealings with have been successful but have been
mainly network (node/edge) based: complex polygonal data is problematic.
Finally, it is nice to have a backend product in the database but what RT is
missing is decent production ready edit tools for the range of GIS editors out
there: MapInfo, ArcGIS, GeoMedia, Autodesk Map 3D.
I hope this is helpful.
One interesting question to ask is "what business problem is topology solving"?
> not really be necessary from an educational perspective.
Can you explain what do you mean by this?
regards
Simon
--
SpatialDB Advice and Design, Solutions Architecture and Programming,
Oracle Database 10g Administrator Certified Associate; Oracle Database 10g SQL
Certified Professional
Oracle Spatial, SQL Server, PostGIS, MySQL, ArcSDE, Manifold GIS, FME, Radius
Topology and Studio Specialist.
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