[OSM-dev] Generalisation

Tomas Straupis tomasstraupis at gmail.com
Wed May 2 20:24:08 UTC 2018


Hello

2018-05-02 19:33 GMT+03:00 Marco Boeringa wrote:
> The generalization I wrote about was just a crude basic generalization of
> vector (building) data of OSM using a default tool of ESRI's ArcGIS. The
> specific tool used (Simplify Polygon), has more advanced settings than
> standard Douglas Peucker, but by itself does nothing really special other
> than weeding out vertices / nodes. I just attempted to use it with different
> tolerances to see what the results would be, and concluded the resulting
> defects in building topology, were not worth the reduction in file size.

  You've probably used this:
  http://desktop.arcgis.com/en/arcmap/10.3/tools/cartography-toolbox/simplify-polygon.htm

  And I'm talking about this:
  http://desktop.arcgis.com/en/arcmap/10.3/tools/coverage-toolbox/simplify-building.htm

  But both of these are closed and tied to their proprietary
architecture. And there is even less information on implementation
than in first(?) scientific paper about actual building generalisation
algorithms: Sester M. ( 2000 ) Generalization Based on Least Squares
Adjustment In: ISPRS (ed.)

> However, as to interesting stuff to read: our national Kadaster of the
> Netherlands, is actually the very first and only national mapping
> organization world wide, that has successfully managed to implement a fully
> automated generalization work flow for generating 1:50k maps from 1:10k
> maps, including landuses, waterways, highways, but also generalizing
> build-up areas and buildings. They used a range of cartographic
> generalization tools from ArcGIS (that I didn't use...).

  Congratulations to national Kadaster, but I'm not sure you're
correct about "first and only". Our local (Lithuanian) land agency (or
to be more specific gis-centras) has completed automated
generalisation 1-2 years ago (using esri tools as well). As far as I
know fully automated and done in ~day.

  Most GIS people use a work by Sandro Savino "A solution to the
problem of the generalization of the Italian geographical databases
from large to medium scale: approach definition, process design and
operators implementation". Author claims to have completed automated
generalisation for Italy and it dates to 2011. This work is very
interesting because instead of referring to closed commercial tools it
has a very detailed description of how to actually do this and that.

  Also Swiss Topo is known to be doing a very high quality
generalisation for years(?).

  But thank you for your links, it is interesting to learn how
different countries handle generalisation.

-- 
Tomas



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