[OSM-talk] High Cartographic Quality Label Placement on OSM-based Map
maxim.rylov at geog.uni-heidelberg.de
Fri Jul 12 18:30:30 UTC 2013
7/12/2013 12:18 AM, Christoph Hormann wrote:
> Could you explain in what ways this is the case. Since different types
> of labels are shown in various maps direct comparison is difficult.
> You seem to very well avoid overlaps between labels and none the less
> you are able to put quite a lot of them on the map but non-label
> feature do not appear to play a role in label placement and there are
> some strange priorities. Is the algorithm available as open source?
Avoiding of overlaps in map labeling is a constraint that is necessary.
We can compare the map labeling on osm.org and on our map with the help
of the list of cartographic rules for point-feature labeling.
For example, they are:
* R1. *Type arrangement should reflect the classification, importance
and hierarchy of objects.
*R2.*The lettering to the right and slightly above the symbol is
*R3.*Names of coastal settlements should be written in water.
*R4.*Label should be placed completely on the land or completely on the
*R5. *Names should not be too close to each other
*R6.*Labels should not be excessively clustered nor evenly spread out.
*R7. *Each label should be easily identified with its point-feature.
Ambiguous relationships between symbols and their names must be avoided.
*R8. *Label should not overlap other significant features of the
cartographic background or do it as little as possible.
As far as I know Mapnik and other open-source software take into account
only the rules R1, R2 and R5 (partially, returns labels that are evenly
spread out, example - http://maps.skobbler.com/on z11).
And the "greedy" algorithm that is utilized to solve the label placement
problem returns rather poor approximation to the optimum as there is no
> Is the algorithm available as open source?
Unfortunately, the algorithm currently is not open-source, but the model
that we elaborated and used will be published as a journal paper within
the next few months.
All the best,
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the talk