[Tagging] [OSM-talk] Should we map things that do not exist?

[Stefan Tauner]

On Mon, 4 Jan 2021 22:25:49 +0000
Paul Allen <pla16021 at gmail.com> wrote:

> From aerial imagery alone, you cannot tell that the alignment passes
> through the living room, only that it passes through the building.

Although this was a quite obviously a tongue in cheek I want to point
out, that this IS possible with the sufficiently precise data that is
available in some countries. In Austria it is no problem to see details
of line markings on roads, individual thin masts, power lines (yes, the
lines) or waste bins for example and the offset is also low enough most
of the time. If both objects are still visible it is no problem to
determine their relative spatial placement with a precision of <<50cm.
The Esri Clarity layer in JOSM often provides these local aerial images
in an easy to access globally available manner in JOSM (much better
than Bing in parts of the US). If there are some clear indicators of
the rail/alignment still visible from above nearby this should be enough
for <3m precision easily.

-- 
Kind regards/Mit freundlichen Grüßen, Stefan Tauner