In practice, most objects in OSM (including the largest ones such as coastlines and land boundaries of countries) are traced with small segments whose two end points have very near latitudes whose difference is much below 1° if this is not the case the polygons should be improved to add missing intermediate points if arcs are not traced along a parallel or meridian (this should be done for roads). Latitudinal distance along any meridian (exact) latitudinal distance (in metres) = (decimal latitude A - decimal latitude B) * 111 120 m longitudinal distance along an average parallel (approximation the highest the difference of the two latitudes, the lowest is the precision) longitudinal distance (in metres) ≈ (decimal longitude A - decimal longitude B) * cos(average latitude) * 111 120m The loxodromic distance between two points A and B (on the WGS84 reference geoid) may be approximated by twice the quadratic average of the two distances below if the difference of latitudes is not too important (less than about 10°):
So, for example, in Germany (50 ° N) the meridians are about 2/3 as large as on the equator and the accuracy is correspondingly higher.ĭistance along a parallel depending on latitude The value in meters is to be multiplied by the cosine of the latitude (except along the equator). The precision of longitudes is dependent on the latitude : the higher the latitude, the closer the meridians are to each other.
0 kommentar(er)
