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In the city where I live, the main street is depicted on maps as running exactly north/south, and its main cross street is depicted as running exactly east/west. However, in reality, the north/south street runs on a different angle, as does the east/west cross street. I'm assuming on our city touristy and transit maps this is done to make it them easier to understand, whereas on the detailed road maps "true" angles are depicted. (A similar principle, Gis software in my vehicle allows me to set it so that whatever direction I'm driving in is straight up (and down) on the 2d map, or I can set it so that it shows me driving at whatever angle is the road's true gis coordinates)

My question is, is there a name for the type of map, or the principle behind creating those types of map, that depict the main streets as running exactly north/south east/west (as the case may be), or conversely, is there a name for the maps that depict "true" angles of the streets? (please include information about how cartographers describe the differences between these two types of map).

(note, I've seen several websites that list 5 or 6 principles of map making but none of them refer to this concept/idea explicitly, although I assume it falls under the general principle of Legibility, which is one of the 5 key principles of map making)

  • Do you have a visual example of this type of map? – Aaron Jul 9 '17 at 22:43
  • @Aaron I don't have one handy. If there's something about the language of the question that you need me to clarify, I will endeavour to make it clearer. However, the general idea is that on many tourist maps streets are depicted as running directly north/south and perfectly east west, intersecting at 90% angles etc, whereas in actuality the streets don't like run perfectly north/ south etc. I suggest browsing tourist maps of cities that you're familiar with if it's still not clear. – Leahcim Jul 9 '17 at 22:52
  • There is the equal-area (also called equivalent, equiareal or authalic) projection that preserves areal relationships and distort angles (progonos.com/furuti/MapProj/Dither/CartProp/AreaPres/…). Even unlikely that could be the reason why the roads dont have accurate angles. – user613068 Jul 9 '17 at 23:08
  • I think it's deliberate that the roads don't have accurate angles. The intention of tourist maps (I assume) is to make them more "legible" (which is why I referenced that principle in my OP)" – Leahcim Jul 9 '17 at 23:56
  • We can have topologically correct maps, such as the London tube map, no angles, or distances are true, but it helps you navigate the system without issue. – nmtoken Jul 10 '17 at 13:40
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This type of map could be referred to as an "artistic rendering". These types of maps usually do not have any type of spatial reference as you would expect from Google Maps, OpenStreetMap, or National Geographic print maps. Maps such as these are usually created entirely in illustration software such as Adobe Illustrator or are drawn by hand rather than being produced with GIS software.

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I'd call it the orientation of the map. There is nothing special about north-is-up (just a convention, and it obviously varies according to whether you're working magnetic or true north). There are cases where the map can't be north-up (e.g. a polar projection of the Arctic or Antarctic).

I'd consider this kind of change to be a small part of cartographic license which (to me) is the cartographers' obligation to communicate information consistent with the intent of the map. Different scales, different representations, different directions, choice of features and so on are all parts of the communication choices.

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