[Tagging] Using multipolygons to map bays in Alaska

Christoph Hormann osm at imagico.de
Fri Nov 16 13:06:39 UTC 2018

On Thursday 15 November 2018, Kevin Kenny wrote:
> >
> > Data of subjective value for a specific application (like low
> > quality label rendering) - yes, obviously.  Meaningful additional
> > information about the verifiable geography - no, i don't think so.
> By 'low quality', I presume you mean 'of a quality that can be
> achieved algorithmically rather than by manual label placement by a
> skilled cartographer?' Otherwise, what's your approach to higher
> quality?

No, what i mean here is that labeling a bay based on the non-verifiable 
polygon drawing of the mapper alone without taking into account the 
geographic context (like the coastline, potentially also other features 
like neighboring straits and bays with their labels) is inevitably low 
quality.  The additional non-verifiable data is only useful for such 
low quality efforts, it is of no use for higher quality approaches.

> [...]
> It is only once the spatial extent is determined that a renderer can
> do a good job of label placement.

No, this is an insight that you get at one point when working on rules 
for high quality labels that for optimal label placement of features 
like a bay or a strait which largely have no verifiably defined two 
dimensional extent knowledge of an arbitrary declared extent is not 

Maybe that is a special perspective i have as an engineer working as a 
designer - as an engineer you learn that degrees of freedom that are 
not contrained by design requirements are not a nuisance but a highly 
desirable chance to actually optimize efficiency and quality.  Taking 
this over to cartographic design the geometrically undefined nature of 
a bay or strait is what gives you much of the freedom to optimize the 
design and placement of a label and scuttling that with the illusion of 
a defined extent is sad.

Christoph Hormann

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