[OSM-dev] Generalisation

Marco Boeringa marco at boeringa.demon.nl
Wed May 2 20:37:06 UTC 2018


This is a bit like the Vatican saying to Galileo that the earth doesn't 
spin around the sun, but the other way around...

Have you even looked at the links I provided? I can assure you (living 
in the Netherlands myself, I think I have better appreciation of this 
specific effort), that this is no "marketing hyperbole".

They did fully automate the generalization process from a 1:10k base to 
1:25k and 1:50k. The two years update interval is the amount of time 
needed to update the base 1:10k TOP10NL vector map.

Even if you fully automate the generalization process to produce medium 
and small scale maps from large scale ones, you still need time to 
update the base 1:10k large scale one. Two years updating means they fly 
each part of the entire country - capturing 1:5k high resolution stereo 
aerials - in that period of time. That two year cycle is a huge 
achievement, in most countries, the update cycle of topographic sheets 
is minimum 5-10 years, in some cases 25 years..., meaning it takes e.g. 
a minimum 5-10 years before a certain publicized map sheet, is updated 
to the latest on the ground state as captured by new aerials (which may 
already be outdated by the time they are truly processed to map sheets). 
The two year cycle in the Netherlands, is in fact to a large extent the 
result of the automated generalization employed for the medium and small 
scale maps, freeing up workforce to maintain the base 1:10k TOP10NL 
vector map, instead of needing to maintain multiple map series concurrently.

"And also it is ultimately: Demo or it didn't happen - at the moment the 
only thing you can get at 1:50k is the old style map:

This is a serious misunderstanding. This is the a rasterized version of 
the new style 1:50k vector map based on generalization, that just 
happens to look very close to the originally manually generalized one: 
that was the whole target of the effort. They make available the rasters 
for clients, as it is just an easy way to consume the data, styled and all.

"and the processed geometry data set (without any labeling information):

And here you are actually pointing out one of the 1:50k vector products 
(in GML format) that they make available based on the described new work 
flows, so I don't understand your argument?...



Op 2-5-2018 om 21:02 schreef Christoph Hormann:
> On Wednesday 02 May 2018, Marco Boeringa wrote:
>> [...]
>> 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, [...]
> That is largely marketing hyperbole.  The fact that no one tends to
> define the term "fully automated" and "successfully" in such context
> should serve as a warning.
> Institutional mapping in various countries has used algorithmic geometry
> processing in production of maps for quite some time but most of them
> (including the ones in the Netherlands) tend to still maintain a
> traditional view of the cartographic process.  They are for example
> speaking of a two year update interval which would be quite curious if
> the processes were indeed fully automated according to the common
> understanding of this term.
> And also it is ultimately: Demo or it didn't happen - at the moment the
> only thing you can get at 1:50k is the old style map:
> https://www.pdok.nl/nl/producten/pdok-downloads/basisregistratie-topografie/topraster/topraster-actueel/top50raster
> and the processed geometry data set (without any labeling information):
> https://www.pdok.nl/nl/producten/pdok-downloads/basisregistratie-topografie/topnl/topnl-actueel/top50nl
> Without a styled map rendering this is not really something you can
> seriously evaluate (although you can see quite a few cases of geometric
> incompatibilities in the geometries).

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