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Google Maps and OpenstreetMap and many other web mapping products utilize the concept of zoom-levels to change the size of the map in a web client. Most people are however more familiar with the concept of map scales(i.e 1:1000, 1:50000 etc) when zooming in or out of a map or considering measurements. When using zoom-levels the scales are not very intuitive (http://api.geoext.org/1.1/examples/zoom-chooser.html). Even desktop GIS software maintains the concept of scales when zooming in or out of digital maps. So why is the concept of map scale not used instead of Zoom-levels in web mapping clients such as OSM or Google Maps? This would enable the maps to be much more functional for administrative purposes for example in land use planing where the use of set scales like 1:10,000 are required when printing to paper.

  • Are you talking about Zoom Levels 1-23? wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Zoom_levels (Google Aerial goes to 23 blogoscoped.com/archive/2007-03-07-n12.html) – Mapperz Mar 21 '14 at 19:13
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    Do you mean the scale at different tile levels? At least with Google Maps, it's because they're subdividing the world with squares and the calc is automated. – mkennedy Mar 21 '14 at 19:14
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    I think this is a legit question. The scales you get from the tile-based schemes that googlemaps and osm uses does not in fact resolve to "nice" scales. If this question is unclear then a lot of the "this is my code, please fix for me"-questions should be put on hold as well – atlefren Mar 21 '14 at 20:05
  • I would vote to re-open this if a few more details were included like what "strange numbers" are being referred to. – PolyGeo Mar 21 '14 at 21:10
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    I'd say that google maps and open street map are NOT meant for people who care about scale numbers... that is, client applications built on Google or OSM are meant for simple audiences who don't care what zoom level (1-23) or scale (1:234,000) they are at... they just care about what they can see on the map! If you're building something for a more concerned/specific audience, I'd say there should be a way to specify in an API what zoom level you'd like to display in the slider... – DPSSpatial Mar 21 '14 at 22:13
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The biggest reason is that the scale is not uniform. Most maps are in webmercator, and it does not preserve distances. At a given zoom level the scale will be different at the equator and at an higher latitude.

The second reason is that scale really doesn't have much meaning when you talk about webmaps.

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