[OpenStreetMap] #4681: Export scale does not match exported file

[OpenStreetMap]

#4681: Export scale does not match exported file
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 Reporter:  bubaya        |      Owner:  rails-dev@…
     Type:  defect        |     Status:  new
 Priority:  minor         |  Milestone:
Component:  website       |    Version:
 Keywords:  scale export  |
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 Given the following example: [http://parent.tile.openstreetmap.org/cgi-
 bin/export?bbox=5.0,50.0,5.1,50.016666&scale=10500&format=pdf]

 This map extract is 1' lat high, this is 1852m. The scale is 1:10500.
 Hence, the exported pdf should be 17,64cm high. In fact, it is 34,6cm
 high; that means a scale of 1:5353.

 The same problem if I export images: When I export the same area as a PNG
 image, the image is 981px high, and has a resolution of 72ppi. That means
 a height of 34,6cm, the same as the PDF. To match the 1:10500 scale, the
 image would have to have a resolution of 141.3ppi. If I play around, I do
 not get a constant resolution that would match the scale, but always value
 between 140 and 145ppi.

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Ticket URL: <https://trac.openstreetmap.org/ticket/4681>
OpenStreetMap <http://www.openstreetmap.org/>
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