[Talk-GB] Definitive map edits

[SK53]

The Definitive Map (from whatever source) is likely to be OSGB derived
data; it may be that this is OK in OSM if, and only if, the relevant
council has released it as Open Data with a suitable licence. In general
most of us take a highly conservative approach to various shape files
released by councils (e.g., through Barry Cornelius Rowmaps site), and at
best use the data to do on-the-ground surveys,

An additional point is that an footpath mapped from old maps, council maps,
shapefiles, aerial images is nothing like as useful as one mapped by
someone walking it. The stiles and gates, which side of the hedgerow etc.
can only be added by a ground survey. Furthermore these often show that,
for instance the path might be a Right of Way but is not practicable or
that the actual path follows a route distinct from the line shown on the
council maps.

Most so-called definitive maps are not definitive: the associated textual
statement is usually more significant.

In summary this type of mapping is probably not under an acceptable licence
and unless a ground survey follow up is planned is rather less useful than
the mapper thinks (I know I've done this in the past). Note if this data is
available as a shape file it is relatively straightforward to create
another shapefile showing those paths missing from OSM, or those on OSM or
not marked as a PRoW (In most places we have more of the latter).

Jerry

On 15 March 2016 at 18:57, Neil Matthews <ndmatthews at plus.net> wrote:

> Anyone know whether "definitive maps" are suitable as sources for OSM?
>
> I'm seeing a lot of edits today by the same author that have comments
> about "the definitive map", e.g.
> https://www.openstreetmap.org/changeset/37850221
>
> There are URLs for the source, but they don't seem to be valid?
>
> Cheers,
> Neil
>
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