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Is there a map projection that can accurately represent reality at a local area, i.e. when transforming the map could I choose an area that I care about accuracy and allow distortions elsewhere?

Like this map: http://upload.wikimedia.org/wikipedia/commons/thumb/8/83/Tissot_indicatrix_world_map_equirectangular_proj.svg/450px-Tissot_indicatrix_world_map_equirectangular_proj.svg.png

I want to choose where the distortion happens.

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  • generally yes. Every projection has its parameters that define the characteristics and where for instance standard parallels are set on which distance is true etc. This all depends on the projection you choose. A GIS usually lets you adjust these parameters. I recommend flexprojector.com as a good free tool for learning to work with projections.
    – Chris P
    Jul 7, 2014 at 14:16
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    You should consider what you wish to be accurate. You can achieve a faithful (that is, perfectly accurate) representation of areas, of angles, of bearings relative to north-south, of distances from one, two, or three fixed points, and of spacings among lines of latitude; but you cannot make all of these perfectly accurate at once throughout your map.
    – whuber
    Jul 7, 2014 at 18:07

2 Answers 2

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Azimuthal Equidistant Projection may work well. The origin of the projection should be set to the Lat/Long of your local area. Angles and distance from the origin are preserved. Depends on how large your 'local' area is. Distortions increase the further distance you go from the origin.

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If you think of accuracy of distance measurement, mercator or transverse mercator with lat_0 and lon_0 set to the center of your area will do fine.

Mercator has true lengths along the latitude, while transverse mercator has them along the meridian. So it depends on the format of your area which one is better. You can use omerc if you need a rotated grid.

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  • I was looking at this projection webhelp.esri.com/arcgisdesktop/9.2/… It seems to suggest it has an optimum area around the middle latitudes. Jul 7, 2014 at 16:02
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    @user1750289 - yes, if you set the standard parallel parameters to within your area of interest. Usual is to set them at 1/6 and 5/6 of the N-S extent.
    – mkennedy
    Jul 7, 2014 at 17:08
  • @andre-joost - this answer seems misleading to me. Mercator has true lengths along the lat? On the standard parallels, yes. TM has true distance along the central meridian IF the scale factor is 1.0.
    – mkennedy
    Jul 7, 2014 at 17:09
  • I meant the lat and meridian given with x_0 and y_0.
    – AndreJ
    Jul 7, 2014 at 17:53
  • @AndreJoost - if you're using PROJ.4 convention, those are the false easting and northing parameters.
    – mkennedy
    Jul 7, 2014 at 18:27

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