2013/4/1 Stephan Knauss <o...@stephans-server.de>

> Florian Lohoff writes:
>
>> As they were wrong and nobody cared i deleted them.
>>
> A better way of dealing with updated data in OSM is usually to fix and not
> to delete data. Had you considered mailing the users who created the
> original data before removing their work?
>



please take a step back: imagery coverage of external providers is not
geographic "data". I am not saying it is completely useless in cases it
actually describes the boundaries of imagery coverage in areas with few
local mappers (because local mappers usually know the boundaries and don't
need coverage polygons), but when the coverage changes (e.g. gaps get
filled, coverage gets completed) these polygons really become useless.



> In contrast to eg. underground power lines (seen them mapped in Munich) or
> TMC data or obscure boundaries, this is data which is easy to verify and
> used in the more remote areas of the world.
>



used for what? The only purpose I can imagine is find areas in the editor
with few data where good imagery enables you to trace more stuff out of
this imagery. A scope that can be achieved also with external tools like
http://ant.dev.openstreetmap.org/bingimageanalyzer/ and
http://mvexel.dev.openstreetmap.org/bing/



> You might not believe it, but there are areas which still have only the
> low-resolution landsat images. Quite often it's the same areas that lack
> mapping of major highways.



sure, but how do coverage boundaries that show that there is no good
imagery to refine the data help in these cases?



> The imagery boundaries are used to give oversea mappers a hint where areas
> are that can benefit from remote mapping, to complete at least major
> highways and water features.
>


+1, and that's all these boundaries can achieve, and to achieve this it is
essential that the coverage is reflecting the actual state.

Btw.: how many boundaries shall we tolerate? For every imagery provider and
every zoom level? I often encountered boundaries that were more or less
detailed in lower zoom levels but didn't perfectly reflect the situation
for high zoom levels. When tracing in a remote country it is usually
"automatic" that you discover the bounds of the good imagery, personally I
never needed a meta data polygon for this ;-)

cheers,
Martin
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