Lat Long or Long Lat

时光毁灭记忆、已成空白 提交于 2019-11-29 09:02:56

You are correct, there is no standard on the order:

In mathematical functions which do an universal conversion, between x,y or lon,lat or inverse, the lon,lat order should be used, because the x-axis relates to longitude and y to latitude and the x,y order is ususally prefered.

Further, if you program a piece of code which is related to draw a lon,lat coordinate on x,y coordinates (screen), I also would use the lon,lat order because of the direct relation to x,y.

The order lat,lon is the classical one, coming from (old) navigation and geography. I assume that latitude in that field is used first because it was easier to measure (using only a ruler, the sun and a stick for length of shadow measuring). The longitude was not determinable for long time. If you read old adventure reports, they only tell the latitude that their expeditions reached).

I think therefore they use latitude first, the measurement of longitude came later in history, once precise chronometers have been available and transportable.

So for apps that display coordinates info on a screen you should display latitude first.

As mentioned in the comments by @Midavalo, there is a standard for the representation of geographic locations by coordinates: ISO 6709.

It describes that a geographical point is specified by the following four items:

  • a first horizontal coordinate (y), such as latitude
  • a second horizontal coordinate (x), such as longitude
  • optionally, a vertical coordinate, i.e. height or depth
  • optionally, an identification of the coordinate reference system (CRS)

The order, positive direction, and units of coordinates are supposed to be defined by that CRS, but when such a CRS identification is missing -- which is very often -- the data must be interpreted by the following conventions:

  • Latitude comes before longitude
  • North latitude is positive
  • East longitude is positive
  • Fraction of degrees is preferred over sexagesimal (degrees, minutes, seconds) notation

So, unless another another coordinate reference system is mentioned, the standard is "latitude, longitude, (elevation)".

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