Seeing the Wood from the Trees : Generalising OS MasterMap ® Tree Coverage Polygons to Woodland at 1 : 50 000 Scale

The OS MasterMap product from Ordnance Survey (OS) is sourced from a detailed geographic database with Great Britain coverage. OS are conducting research into deriving smaller scale cartographic products automatically from this database. This paper presents details of research into vector-based automated model and cartographic generalisation of the source topographic tree coverage polygons to woodland represented at 1:50 000 scale. The whole symbolisation process is addressed to ensure that the results conform as closely as possible with the current Ordnance Survey raster product specification. Firstly, tree polygons are clustered into autonomous groups, then the polygons are amalgamated into woodland. For each wood, the bounding features are identified and then the wood boundary is simplified with respect to these features. The next step is to slice up the woods by the traversing network features, resolve the conflicts and place tree symbols in the generalised woods. The paper concludes by discussing how the results will be evaluated and what remains to be implemented.