[OSM-talk] source=Google

[Toby Murray]

I will point out here that iD has invented a new changeset tag which I find
useful. It automatically records what imagery layers you use while editing
and throws them into an imagery_used=* tag. This removes the need for users
to manually tag source information if they are just tracing imagery. I
wouldn't mind seeing other editors adopt this convention.

Toby



On Sat, May 18, 2013 at 11:12 AM, Christoph Hormann <chris_hormann at gmx.de>wrote:

> On Saturday 18 May 2013, Yohan Boniface wrote:
> > On 05/18/2013 03:55 PM, malenki wrote:
> > > Dave F. wrote:
> > >> IMO Source should be on the object, not on the changeset.
> > >
> > > +1 (except if there is one changeset for one object (; )
> >
> > This is not my opinion. Let's take a simple example: a school.
> >
> > [...]
>
> The problem is currently neither changeset nor object tags are really a
> good solution for true metadata (that is information characterizing the
> data and not the real world object).
>
> Changeset tags have mainly two problems:
>
> - they always apply to the whole changeset so everything you map
> together needs to have the same metadata.  This might seem to be a
> problem primarily for imports but it can also be troublesome in manual
> mapping - imagine mapping something based on satellite images and you
> need to use different images for various parts due to clouds or even
> the common case of supplementing survey data with Bing images.
>
> - many large objects are included in a lot of changesets without
> actually being substantially modified (like moving a single node in a
> 500 node way etc.)  This means finding the actual changeset a certain
> geometry originates from to get the metadata information is not so
> easy.
>
> The solution in my opinion would be to have separate metadata tags which
> are reset everytime a substantial change is made to the data they refer
> to unless the user explicitly sets them (either individually or for the
> whole changeset).  Geometry metadata tags for example would be reset
> if:
>
> - in case of a node the node is moved
> - in case of a way more than X percent of the nodes are changed (X being
> something like 30)
> - in case of a multipolygon more than X percent of the ways are
> added/removed or substantially modified
>
> This would not be fool proof of course (small changes could accumulate
> to a substantial change without being noticed).
>
> Greetings,
>
> --
> Christoph Hormann
> http://www.imagico.de/
>
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