Allow min-zoom and max-zoom >24 for Imagery sources in the wiki

[Klumbumbus]

polska.e-mapa.net: Buildings at wiki:/Maps/Poland has actually:

        <min-zoom>18</min-zoom>
        <max-zoom>30</max-zoom>

It's not possible to enter it in the wiki due to the following error:

Warnung: Ungültige Wiki-Seite: XML validation for map failed: Element '{​http://josm.openstreetmap.de/maps-1.0}max-zoom': [facet 'maxInclusive'] The value '30' is greater than the maximum value allowed ('24').

[Don-vip]

30 seems excessive to me. 24 is already a very high zoom level for an imagery source and I don't see what we would gain to support increased levels.

[Klumbumbus]

This is the zoom range the source supports. z30 works in JOSM. Why not adapt the imagery entry to these values? Is there more work to do than changing one variable in the trac code?

[Don-vip]

I don't know. Wiktor do you think it can involve a performance penalty? (bigger cache, etc)

[wiktorn]

Replying to Don-vip:

I don't know. Wiktor do you think it can involve a performance penalty? (bigger cache, etc)

I don't worry about the performance/cache penalty, but what's the point? If I remember correctly, zoom 24 is close to resolution that we can handle in OSM database. If my quick calculation is correct, at zoom 30 one pixel is 0.1mm. Who needs such resolution?

[stoecker]

Replying to Klumbumbus:

This is the zoom range the source supports. z30 works in JOSM. Why not adapt the imagery entry to these values? Is there more work to do than changing one variable in the trac code?

A change in the xsd will only affect recent versions. If you use such a feature any old JOSM will no longer be able to load the non-validating file. So there are two reasons no to do it:
a) it has no real sense
b) Keep downwards compatibility.

[Klumbumbus]

OK, imagery entry adapted.