[talk-au] seaward admin boundaries

[Andrew Harvey]

On Tue, 19 Jan 2021 at 11:48, cleary <osm at 97k.com> wrote:

>
> As with other boundaries, I'd prefer to keep administrative boundaries
> separate from natural features even where they approximate and may once
> have precisely aligned.  I'd like to see administrative boundaries
> consistent with the authoritative government source/s while natural
> features such as rivers, coastline etc. are mapped from satellite imagery.
> Even where coastline erodes or changes in other ways, I think the
> administrative boundaries in OSM should remain unchanged until the relevant
> government authority redraws them.
>
> In regard to high-water and low-water marks, I defer to others with better
> knowledge.
>

In my opinion, where the boundary is defined by the natural feature
(coastline, river, road centerline etc) then the boundary way should be
snapped (share nodes) with the natural feature. This provides the most
accurate representation and encodes the "defined by the natural boundary"
information which would otherwise be lost. As the coastline/river etc
changes then the boundaries are kept up to date because they have shared
nodes, this is a feature, not a bug.

This is in contrast to your preference cleary. The PSMA and other
government datasets aren't the exact boundary definition, only a digital
representation of it, if we have a better coastline or river data we should
use ours.

Of course this is all based on that assumption about what defines the legal
boundary, but I doubt it is the GIS files the government and it's 3rd
parties (PSMA) produce. Phil's comments seem to backup this claim too.
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