CLIFF Technologies Ltd'

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CLIFF Technologies Ltd.

• Chris Lilley

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CLIFF Technologies Ltd.

• Company Background
• GIS developer and Support/Maintenance agent
  specialising in GE Smallworld products.
• Original designer and developer of both the
  MapBase and MapSync products.
• MapBase is GEs background map management
  product.
• MapSync is GEs product designed specifically for
  the update of foreground data as a result of PAI.

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MapSync link files

• Like many GIS tools that address PAI issues,
  MapSync started by using OS link files.
• Link files describe change of real physical
  features.
• Clients data has been digitised mostly to be
  relatively correct.
• When client data is not coincident with map
  features, links can cause high levels of local
  distortion producing undesirable results.
• This is now muched reduced because of the work
  done by OS to clean up links and make them more
  dense.

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MapSync link files
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MapSync link files

• Because of their nature link files are associated
  with the background mapping, this means...
• Good at moving mapping or data associated
  directly with mapping.
• e.g. land parcels coincident with physical
  features.
• Not as good at moving linear networks.
• e.g. cable network not coincident with physical
  features but positioned between features (along
  the centre of a footway).

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Client data specific links

• Rather than use links for the mapping, generate
  links for the clients data itself.
• Analyse clients data relationship with respect
  to pre-PAI mapping.
• Transform the clients data to have the same (or
  similar) relationship with the post-PAI data.

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Analysis using OS MasterMAP

• To produce better results from the client data
  analysis, OS MasterMap data was used allowing
  scrutiny of the areal type objects.
• MapBase can maintain the geometric history of
  OS MasterMap data.
• Load the pre-PAI OS MasterMap data followed by
  the post-PAI OS MasterMap data, which
  automatically established a connection between
  the old and new polygons.

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Transforming using OS MasterMAP areas

Original map area e.g. a footway
Clients network data within the area but not
coincident with it.
Area is moved as part of the PAI programme.
Each point in network is analysed to determine
its relationship with the original area.
Each points relationship is then applied to the
new area to get a best fit.
and the transformed network is then
determined.
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Transforming using OS MasterMAP areas

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Transforming using OS MasterMAP areas

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Strategies for determining spatial relationship

• Different strategies on determining the spatial
  relationship between client data and OS MasterMap
  are being tested on real data.
• These include
• Proportional Perpendicular
• Equidistant Perpendicular
• Equidistant Boundary - Still requires OS link
  files as a guide.

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Conclusions

• The transformation of clients data will probably
  never be 100 automatic.
• Using OS MasterMap to produce data specific links
  increases the number of situations that can be
  automatically dealt with.
• Most of the strategies investigated do not
  require the OS link files and so processing is
  reduced.
• Reduction of required effort will help to bring
  PAI processing into the realms of the normal
  update process.

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Questions

• Chris Lilley
• CLIFF Technologies Ltd.
• email enquiries_at_cliff-tech.co.uk