[mapserver-users] scalebar wrong with epsg:3857

[b.j.kobben at utwente.nl]

No scalebar is ever correct on any map if the map is not having an 'equal area' (sometimes called 'equivalent') projection -- meaning the areas are comparable/not distorted over the map. The 3857, being a Mercator projection is not, and indeed here the distortions reach from none at the equator to huge at the poles (officially endless - theoretically the poles are points, but depicted as lines...)

The software you use makes no difference, although some specialised ones let you show distortions using indicators called Tissot-indicatrices)

http://kartoweb.itc.nl/geometrics/ 
https://en.wikipedia.org/wiki/Tissot%27s_indicatrix


--
Barend Köbben
 

On 28/01/2018, 20:36, "mapserver-users on behalf of Richard Greenwood" <mapserver-users-bounces at lists.osgeo.org on behalf of richard.greenwood at gmail.com> wrote:

The scalebar created by MapServer 4.6 is too short when I'm using epsg:3857. I'm guessing that it's correct at the equator and gets worse as you get further north or south? Has anyone else experienced this and possibly have a solution?


Thanks,
Rich


-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com <http://www.greenwoodmap.com>