render icon and icon+text for large POIs on lower zoom levels

[matkoniecz]

See http://www.openstreetmap.org/?mlat=41.9025&mlon=12.4534#map=15/41.9025/12.4534 http://www.openstreetmap.org/?mlat=49.6216&mlon=6.1412#map=16/49.6216/6.1412 http://www.openstreetmap.org/?mlat=51.5146&mlon=-0.1530#map=15/51.5146/-0.1530
http://www.openstreetmap.org/?mlat=51.5805&mlon=4.7282#map=15/51.5805/4.7282

see also #1055

superset of #1022 #1020 #1019

[matthijsmelissen]

I have been experimenting with this, but it gives some unexpected results.

• Loads of car shop icons showing up at low zoom, and little other shops.
• With threshold 750 pixels, on z16, only some clothes shops show up, while their is still loads of empty space. Showing only some clothes shops gives the impression that there are only a handful of clothes shops in the city. Same for other POI.

I think we should keep rendering all POI on z17, because z18 is too late for small rural shops.

What would you use as threshold? I think 3000 pixels (the threshold for labels) is too high for this to have any effect, because hardly any POI reaches 3000 pixels before z17.

[matthijsmelissen]

Also note that 67 % van of the supermarkets and 62 % of the department stores are tagged as node only.

[pnorman]

I have been experimenting with this, but it gives some unexpected results.

Loads of car shop icons showing up at low zoom, and little other shops.
With threshold 750 pixels, on z16, only some clothes shops show up, while their is still loads of empty space. Showing only some clothes shops gives the impression that there are only a handful of clothes shops in the city. Same for other POI.
I think we should keep rendering all POI on z17, because z18 is too late for small rural shops.

What would you use as threshold? I think 3000 pixels (the threshold for labels) is too high for this to have any effect, because hardly any POI reaches 3000 pixels before z17.

I think the basic problem is that buildings with multiple POIs within are generally mapped as nodes inside of the building way, and these will have zero area. I could see adding rendering at lower zooms to large features, but I don't think we want to take away at higher zooms.

This will also tend to render more car shops, as they often have an outside lot which is part of the shop (e.g. http://www.openstreetmap.org/way/158991197) while most shops are just inside. You'll also see more shops of types which tend to be large freestanding buildings, e.g. supermarkets and theaters. This is probably okay, as they tend to be more significant.

[matthijsmelissen]

I don't think we want to take away at higher zooms.

Not sure if I agree - I don't think taking away small museums from z16 would be bad, for example.