The clearest way to express a point is with 3 distinct variables: zone/x/y. Or the zone may be shown next to the X coordinate, either in the same font, or in a different one. The zone is sometimes omitted, sometimes only the zone is given and the hemisphere (north or south) omitted. The UTM notation varies according to which maps and applications it is used for, particularly the zone notation. (WGS84 is the most commonly used geodesic system, notably for GPS). In any case, we must be careful to work in the same geodesic system for each system of coordinates. The reverse calculation is also possible, but is more complicated. UTM coordinates can be calculated from longitude and latitude by an approximation calculation, with an accuracy of a centimetre. However, this calculation cannot be done between points in different zones. Unlike coordinates of longitude and latitude that are expressed in degrees, UTM coordinates allow a direct calculation of distances between points, even if a little precision is lost as we get farther from the central meridian. It is worth noting in passing that the Gauss-Kruger coordinates used, for example, in Germany are defined in a similar way to UTM, but with 3 degree wide zones. The northing always increases towards the north, that is, on maps where north is at the top. This is, to the nearest few kilometres, the distance to the equator from the south pole. In the southern hemisphere, to avoid negative values, 100 000 000m are added. In the northern hemisphere, the northing is defined simply as the distance in metres from the equator. The minimum is 3 degrees west of the meridian and the maximum is 3 degrees east of the meridian. The values of the x coordinates range from 167000m in the west (left of the meridian) to 833 000m in the east (to the right of the meridian). The coordinate is a positive number taken from the intersection of the equator and the zone’s central meridian (ie.
Within each zone, any point is defined by an easting (x) and a northing (y) coordinate, expressed in metres. For example, Europe lies in zones 29-38 or, more precisely, zones north 29-38. Each zone is also divided at the equator into a north zone and a south zone. UTM stands for Universal Transverse Mercator, a cartographic projection system that divides the globe into 60 zones of 6 degrees of longitude each. Below, we explain what UTM coordinates are and how they can be used on the appropriate maps. These coordinates can be used to locate points on many topographical maps as, for example, the French IGN maps at 1:25000 scale (TOP25). The Clubs catalogues contain UTM coordinates. Adapted from an original article by Mario Labelle
0 kommentar(er)
