Move small amenities to z18

[jeisenbe]

Related to #4002, #1745 and PR #1884

Changes proposed in this pull request:

• This PR, similar to closed PR Pushing small amenities to higher zoom levels #1884, moves amenity=atm and amenity=post_box to z18, though in this case they are currently rendered only at z19, while previously they were rendered at z17.
• Also emergency phones are moved back to z18 from z19. Previously they had been rendered at z17

This is an attempt to compromise. While these features were moved from z17 to z19 without consensus, rather than attempting to move them back to z17 we can use z18.

In rural areas these features should be shown at z17, while in some very large cities (e.g. Warsaw) there may be many icons in one screenshot at that zoom level due to the high density of features in capital cities.

[kocio-pl]

What rule would we have after that for choosing zoom levels? I have proposed size rule as rule of the thumb and all the other proposed rules were more subjective or not applicable for some types of objects.

[jeisenbe]

In PR #1884 you proposed z18 for these features. Is there a particular reason that you are no longer in favor of this?

What rule would we have after that for choosing zoom levels? I have proposed size rule

The "size rule" was never accepted by any of the other maintainers of this style, from what I have read. Most initial zoom levels for features in this style have been determined by the significance of a particular feature for general map users at that scale. Large size might make a feature significant at lower scales, but it is not the most important consideration. Places of worship are shown at z16 not because they are larger than other features, but because they are important orientation points at that scale.

[kocio-pl]

I have thought more about the size and would be more following it currently than then, because it's simple, universal and used already in this style (at different scales).

Usually places of worship are indeed larger (higher, which also applies to at least some peaks).

Large size might make a feature significant at lower scales, but it is not the most important consideration.

Which leads me to a fundamental question about importance, which is - for whom it is important and specifically why do you think it applies only to low zoom?

[imagico]

This is an attempt to compromise. While these features were moved from z17 to z19 without consensus, rather than attempting to move them back to z17 we can use z18.

More specifically this change would be a partial revert of #2993, #3372 and #3445.

While i don't mind this change in principle if it helps moving us back towards consensus i am unsure if it actually does.

With these changes (as in particular became clear in the discussion on #3372) the massive schism in the fundamental approach to cartographic design that we struggle with became very visible to everyone i think.

I don't think ultimately trying to make compromises between two very different and fundamentally opposite strategies will lead us very far. Yet it is good to try addressing this matter as one of the key manifestations for the loss of consensus on cartographic strategy we struggle with now.

Regarding the change itself and independent of the whole backstory - Essentially most has already been said in #1884 back in 2015.

[jeisenbe]

Rebased for v5.0.0

[Adamant36]

I had suggested a while back that z18 is kind of an under used zoom level that could be used sort of in this way, except more planned out. Just rendering random things there just to compromise though would cause it to be an unplanned out icon dump in a similar way to how z19 currently is. That said, I think z18 has some potential as a place for related icons that don't fit in well at z17 or z19, or something.

[imagico]

Works fine.

[jeisenbe]

I will wait till after v5.0.0 to merge this.