[OSM-newbies] Boundaries and Roads

[Sam Kuper]

On 8 April 2012 20:51, Bernd Vogelgesang <bernd.vogelgesang at gmx.de> wrote:

> **
> from a GIS-persons point of view, you alway should avoid gaps in your map
> ( = in your data).
> Cartographic work is always generalizing the world, and only because you
> COULD go into detail in the sub-meter sphere technically with the digital
> means nowadays, you should should ask yourself: what is it good for?
>
> So, what would be the information you provide, leaving a blank space
> between a field and a road?
> Actually none, cause you do not specify what this gap is, although its
> quite clear that it's something between the road and the field.
> But when its already obvious that there are strips of surface which do not
> belong neither to roads nor fields, you could right away leave them out and
> align the border of the field directly to the road.
>
> In digitizing you normally decide about the map scale of the end product.
> With OSM-maps, thats a little bit difficult, cause there is no common sense
> about the usage, and therefor also about the production-scale.
>
> The planned scale is important, cause it decides about the precision you
> need to get a satisfying result.
> E.g. when you want to have a map in 1:5000, you normally digitize your
> features at a scale of 1:2500 or 1:2000.
> The human eye can not distinguish features smaller than half a millimeter
> on a screen or on paper.
>
> With a map in 1:5000, 1/2mm on screen is 2,5 meters in reality. Thats the
> planned "error" you are "allowed" to produce, cause on the planned scale,
> you can't even see it.
>
> So the question should always be: what is the planned usage and what is
> the benefit from increasing the accuracy?
>
> A field border outside a village is much less interesting than borders and
> features in a town center.
> When the mapped part is mostly relevant for navigating, so as a real
> street map, you could easily set your planned scale to 1:25000 or even
> higher (with the resulting need for generalization), as normal users will
> watch it in that scale anyway to get the overview they need.
> If it's a feature of high interest, you could set your planned scale to
> 1:1000 or lower, with a resulting need of higher accuracy.
>
> [...]
> (please be aware: this opinion might be in conflict with some holy
> OSM-rules set up by some OSM-priests i do not know and do not care about.
> This is just cartographic common sense)
>

Amen; and I don't see any reason why we shouldn't be aiming for OSM to be
as accurate as possible.

I'd be thrilled if the fine scale maps used by local authorities to settle
boundary disputes and planning applications and so on were scanned and used
to refine OSM, and see no technical reason why this shouldn't, in time,
occur - except for the archaic insistence that in OSM, roads must be
unrealistically represented as lines.
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