8 Oct 2011

Technology: PostGIS v2.0 a game changer?

PostGIS for PostGres
For many years there has been a limited choice of geodatabases when looking for a single solution for all geodata models. Only Oracle Spatial and ESRI offered comprehensive coverage of spatial models. Oracle Spatial provided database models and algs for vector, network, raster and topology in addition to the usual database refinements and in database geocoding. ESRI offered ArcGIS Server with comprehensive support for Vector, Network and Raster models but left topology to the clients and had no offering for geocoding.Competitors such as PostGIS, MapInfo Spatialware, Microsoft SQL Server and MySQL only offered support for vectors.

It seems the status quo may be about to change....

The elephant in the room has started to shuffle its feet towards the finish line. PostGIS version 2.0  not only has big plans but appears to a considerable way into delivering the promise of support for network and raster models. For those of you in the US a tiger geocoder is also available. It looks like the initial support will provide a reasonable coverage of raster and topological models but as always seems to be the problem with open source projects there is very little supporting visual tools.

Raster support is delivered through dedicated database data types for raster and GDAL based PostGIS drivers to support a wide range of raster formats. There is reasonably rich support for a first edition including:
  • Range of functions to access raster metadata
  • Raster band manipulation
  • Raster processing
    • Raster value manipulation/calculation (Algebra, reclass, value manipulation)
    • Reprojection
    • Vector to raster conversion
  • Transform to GDAL formats
Support for topology is also provided using PostGres data types. The implementation looks less mature than the raster model appearing to offer predominantly CRUD and import/export style capability only at this stage. There are also limited support for transforming data into the topological model in the database.

Vector  Geometry, Geography and Linear Referencing
PostGIS already has comprehensive support for vector geometries including 2D, 3D and linear referencing. PostGIS also supports geography types often used for global representations in its vector model.

PostGIS v2 will be worth watching in 2012 as it heads strongly into the world of GIS. The open source community makes a strong step forward with this release.