Radius Topology - FAQ
What is Radius Topology™?
Radius Topology™ is a server side component that provides powerful data
cleaning and analysis functionality for data stored in Oracle9i / Oracle
Database 10g. 1Spatial's Radius Topology™ works behind the scenes,
automatically adding topological intelligence to data. Existing Oracle
spatial
software and GIS (Geographical Information System) applications can
continue to be used unchanged. Radius Topology™ corrects your geometries
based on user-defined tolerances in order to create additional topological
information for both existing data as well as new updates as they occur.
This
topological information provides very powerful data analysis and
enhancement functionality.
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Is this a new technology?
1Spatial are geospatial experts and have been selling spatial processing software for 30 years and topology products for 15 years. The Topology library in Radius Topology™ has been used for many major projects including OS MasterMap® conversion and maintenance flowlines.
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What are the features of 1Spatial's Radius Topology™?
- Automatic cleaning of mis-aligned data
- On-the-fly snapping of digitised data
- Identification of existing geometric errors
- Rejection of new geometric errors
- Ultra-fast spatial queries
- Powerful editing of shared geometry
- Powerful data analysis
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What are the benefits of 1Spatial's Radius Topology™?
- Reduces project time and costs by automating complicated manual processes
- Increases Return on Investment (ROI) in a centralised Oracle warehouse by
aligning disparate datasets
- Maximises existing investments in Oracle and COTS geospatial editors by
providing enhanced cleaning functionality for existing tools
- Adds intelligence at the data level to help creation of new services and
more detailed data audits, providing fast and accurate quality measurement
- Assured accuracy and quality of data. Improve services and business
decisions by basing them on the best quality data
- Faster queries reduces need for expensive hardware, lowering the cost of
deployment
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How does Radius Topology™ work?
Radius Topology™ is deployed as a DLL or Shared object on the database server, along with some PL/SQL packages and a Java administration tool. When you set up Radius Topology™, you specify which tables of your data should be topologically structured, and how the data in these tables should interact and snap together.
You then run a structuring process, which snaps the data together and creates topological information. Structuring the data together removes misalignments such as gaps, slivers, overshoots and undershoots. It also identifies any geometric errors such as spikes, kickbacks or duplicate points. The topological information can then be used to perform ultra-fast queries on your data, or powerful quality checks, such as identifying missing polygons, or finding pipes that are unconnected.
Since Triggers are placed on you data tables, any subsequent edits to the data cause the data to be automatically snapped and cleaned on-the-fly, and the topological information is automatically maintained through the life of the data. You then know that your data stays clean and connected from now on.
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Do I need to learn anything new in order to use Radius Topology™?
Radius Topology™ uses only Oracle native types and functions and the techniques required to maintain the data will be very similar to those required for other data. End users won't be required to learn anything new. Some users, and most programmers, of Oracle spatial applications will be able to gain extra benefits by choosing to learn more about Radius Topology™.
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What GIS applications will work with Radius Topology™?
Any application that reads or writes geometries to an Oracle database can benefit from Radius Topology™. This includes desktop GIS/CAD applications, data importing and translation tools, or thin-client web based systems. Radius Topology™ is a server side solution that integrates 1Spatial's spatial technology into Oracle's standard databases. Therefore the only requirement is that you are using Oracle9i or Oracle Database 10g and Oracle's geometry type to store your data.
Another advantage of Radius Topology™ being a server-side solution is that a web solution is immediately possible. Our channel partners will be providing appropriate web clients. Any OGC compliant Web Map Server will be able to utilise Radius technology. Radius is truly client-agnostic. 1Spatial will focus on its core expertise in geospatial database management.
To check which applications which have been tried and tested, contact
1Spatial.:
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Why is Radius Topology™ server-side?
There are several benefits including
- Provides intelligence to thin-client applications
- Can be used in a multi-user environment
- Can work with many GIS applications
- Allows powerful whole-dataset topology queries
- Efficiency - server does the work
- When multiple users are involved, license cost is reduced and rules only
need to be defined once, saving time and effort. Reduces Support and
Maintenance costs by having a single server-side application
- Overall consistency maintained
- Ease of installation
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What types of Spatial queries can be performed faster using Topological queries?
The types of spatial queries that can be performed topologically are those which test for direct interaction between features in the database, such as: touches, crosses, adjacent, contained, inside, co-linear. Queries that cannot be performed topologically are those which test for disjoint relationships such as 'within 3 Km', or between arbitrary geometries, such as 'within this view window''
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What benefits will Radius Topology™ bring to my GIS applications?
- It enables many applications, including very simple web-based clients,
to update the data while continuing to ensure its integrity. Maintenance of
the server centralises the definition of the rules that define how different
types of spatial data interact. This means that a standard set of rules is
used regardless of the application, increasing the data quality for all
- When creating topological information, Radius Topology™ can automatically
clean up data errors such as gaps, slivers, overshoots and undershoots. More
serious problems in the data are identified so that they can be fixed
manually. This increases data quality, leading to improved services and
business decisions
- It allows easy editing of shared geometry (e.g. one edit moves all
connected pipes or updates adjacent polygons). This reduces the risk of
introducing errors when modifying data, and increases productivity
- A wide range of spatial queries can be answered much faster than by using
standard Oracle Spatial. The relationships between topology primitives are
stored explicitly in the model and may be traversed quickly without
requiring expensive geometric comparisons. Most queries can be performed
between 2 and 200 times faster, sometimes more! This can improve user
experiences, open up new possibilities and could achieve required
performance using lower cost hardware.
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Do GIS applications need to be changed in order to take advantage of the benefits that Radius Topology™ brings?
No, Any application that uses SQL to read and write SDO_Geometries in Oracle can benefit. To benefit from the faster querying functionality, an SQL operator is provided and can be used within SQL queries.
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Which platforms does Radius Topology™ support?
The platforms currently supported are:
- Windows 2000/XP/2003 Server
- Linux RedHat 7.3 +
- Solaris v8 +
- HPuX v11 +
- IBM AIX v5.2+
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Does Radius Topology™ impose any limitations on data models?
No, data models can be completely flexible, for example you may require one table for all feature types, or one table for each feature type, or a combination of both, or arbitrary groupings of features in a range of tables. Both tables and views can be used, and the geometries can either be from a stored column value, or returned from a function. In addition, features from any or all of these tables can interact in one or many independent topological layers.
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What version of Oracle do I need to be using?
Databases
Oracle9i Release 2
Oracle Database 10g Release1
Oracle Database 10g Release2
Editions
Standard Edition (with Locator)
Enterprise Edition (with Spatial)
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Is Radius Topology™ compatible other Oracle technologies, such as Real Application Clusters or Oracle9i Application Server?
Yes, Radius Topology™ works within Oracle using standard Oracle features, so it works seamlessly alongside server-side technologies such as Oracle9i AS and RACs
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What type of geometries can be handled by Radius Topology™?
The following geometry types are supported for 2D data:
POINT, LINE, POLYGON, COLLECTION, MULTIPOINT, MULTILINE, and MULTIPOLYGON.
The following geometry types are supported for 3D data
POINT, LINE, POLYGON
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What about 3D data?
Radius Topology™ can structure 3D data. When we talk about 3D data, we mean 2.5D data, where each vertex has a height (or z value). In Oracle this is stored as an SDO_GEOMETRY with a GTYPE of 300x. This does not mean volumetric 3D.
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Is the topology data in 3D?
No, topology primitives are still 2D and the relationships between features are calculated in 2D. Any 3D features will continue to be maintained in 3D.
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Does the height information affect how topology is created?
No, when topology is created the heights are ignored. This means that, for example, if a road crosses another road over a bridge, there will always be a topology node created where the roads cross. Each road, however, will keep its height information and one road will still be higher than the other (unless z snapping is specified, see below)
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Does the height information get altered by snapping ?
Height information is only altered by snapping if a Z Snapping Tolerance is specified. This tolerance is global to a manifold and is specified when creating a manifold. If two 3D features are snapped together, then each snapped vertex will have its z value snapped if the z values are within Z Snapping Tolerance of each other.
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What if you don't want Z Snapping?
Then leave the Z Snapping Tolerance as NULL or zero. If you specify a very large tolerance, the z values will always be snapped.
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What happens when new vertices are added to 3D features?
If snapping causes new vertices to be added to 3D features, then the heights for these new vertices are linearly inferred from the heights of the vertices on either side.
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Can you structure 2D and 3D data in the same manifold
yes, as long as the 2D and 3D features are in different tables.
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Can you structure a table that contains 2D and 3D features?
No, a table must only have one type of geometry. Also, Oracle will not allow you to build a spatial index on a table with more than one type of geometry.
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Can you do topological queries for 3D relationships?
No, since the topology is still in 2D, then topological relationships are only meaningful in 3D. For example, two 3D geometries at the same location are considered to interact, even if they are at different heights.
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What types of 3D geometries can I structure?
3D Geometries of type point, line and polygon can be structured. 3D Geometries of type multi- or collection cannot be structured. Any of these types of geometries can be structured if they are 2D.
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What do you mean by cross-schema structuring?
Radius Topology™ allows you to structure tables together into the same manifold, even when they are stored in different Oracle Schemas. Topological querying is also enabled across these schemas. This allows features from tables owned by different users to be automatically snapped and aligned with each other.
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What permissions do I need for cross-schema structuring?
The user who owns the manifold data needs select and update privileges on each table that needs to be structured.
In addition, each user who owns data to be structured will be granted select access on some topology tables in order to enable cross-schema topological analysis.
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Can Radius be used with other relational databases, such as DB2 or SQL
server?
Currently, Radius Topology™ is only available for Oracle. However, Radius Topology™ is designed to be easily redeployed on other databases as the market dictates.
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How are geometry and topology kept synchronised?
When geometries get modified by applications that access Oracle, triggers created by Radius Topology™ will ensure that the topological representation of the data is always up-to-date.
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How are topological queries performed?
Radius Topology™ provides an operator, LSL_TOPO_RELATE, which is analogous to the Oracle Spatial operator SDO_RELATE. This is an ordinary SQL operator that can be accessed by any application.
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How does Radius Topology™ deal with partitioning?
Partitioning is a standard Oracle technique to handle very large tables. Radius Topology™ uses standard Oracle tables to store the topological information, and these tables can be partitioned if required.
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Which standards does Radius Topology™ comply with?
The international standard ISO 19107, prepared by Technical Committee ISO/TC 211, describes an open schema for storage of topological structure. Radius Topology™ implements this structure using Oracle tables and the Oracle SDO_GOEMETRY type. In addition, the emerging GML3 standard from the OGC includes the capability to describe topology for Geographic features. A topological GML3 description of your feature data can therefore be easily created using Radius Topology™.
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