[OSM-dev] Generalisation

[Tomas Straupis]

Hello

2018-04-15 22:54 GMT+03:00 Frederik Ramm wrote:
> The most likely location for this to be discussed is probably within the
> openstreetmap-carto developer community as they would benefit most from
> such approaches. I don't follow their work closely though so couldn't
> say if the issues have been discussed in the past.

  Good point. I'll watch openstreetmap-carto.

>>   Also, maybe there are ideas to translate the thesis mentioned above
>> to English?
> I'm not aware of any plans, but I do know that Arne has quoted similar
> work done by others, and there were many English-language works among
> that, so perhaps if you skim through his literature list at the end of
> the PDF you'll find interesting articles.

  I'm already buried in pdf's from google scholar :-) You start with
one paper, then open references, then references in references and
here you are the "wikipedia effect".

  The point is that Arne's work looks (from what I did understand) at
generalising openstreetmap data, while most papers look at general
data. This is important because OSM tagging does help a lot. Some
generalisation can be done much easier with OSM data because of
additional tags and you can add additional tags describing some real
properties (not designed for the sole purpose of generalisation) of an
objects which could help generalisation. For example with road
generalisation, a lot is written on intersection generalisation.
Having *_link ways or ref tags in OSM helps this effort a lot. Railway
network also has different subtags like main/siding/spur etc. which
also helps a lot. So while generalisation is generalisation anywhere,
but generalisation of OSM data does have some important and useful
differences/advantages.

  Another interesting thing is recalculating/updating generalised
data. "OSM way" is to update very often. So it is important to be able
to recalculate generalised data only on impacted part and it is not as
trivial as calculating "dirty tiles".

  I do not know how much of that is covered in Arne's thesis. Will try
to read/translate German version if there are no plans for
translation.

  Thank you!

-- 
Tomas