Near the equator, the columns of UTM zone 1 have the letters A–H, the columns of UTM zone 2 have the letters J–R (omitting O), and the columns of UTM zone 3 have the letters S–Z. The identification consists of a column letter (A–Z, omitting I and O) followed by a row letter (A–V, omitting I and O). Each UTM zone is divided into 100,000 meter squares, so that their corners have UTM-coordinates that are multiples of 100,000 meters. The second part of an MGRS coordinate is the 100,000-meter square identification. The origin of the MGRS grid, in the Pacific. the UTM grid reference system the article on Universal Transverse Mercator shows many maps of these grid zones, including the irregularities for Svalbard and southwest Norway.Īs Figure 1 illustrates, Honolulu is in grid zone 4Q.įigure 1. This same notation is used in both UTM and MGRS, i.e. The intersection of a UTM zone and a latitude band is (normally) a 6° × 8° polygon called a grid zone, whose designation in MGRS is formed by the zone number (one or two digits – the number for zones 1 to 9 is just a single digit, according to the example in DMA TM 8358.1, Section 3-2, Figure 7), followed by the latitude band letter (uppercase). The northmost latitude band, X, is 12° high. The 6° wide UTM zones, numbered 1–60, are intersected by latitude bands that are normally 8° high, lettered C–X (omitting I and O). The first part of an MGRS coordinate is the grid-zone designation. Grid zone designation UTM zones on an equirectangular world map with irregular zones in red and New York City's zone highlighted GZD and 100 km Grid Square ID, precision level 100 km GZD only, precision level 6° × 8° (in most cases) In instances where the polygon is not a square and has been clipped by a grid zone junction, the polygon keeps the label of the southwest corner as if it had not been clipped. Related to this is the primacy of the southwest corner of the polygon being the labeling point for an entire polygon. When changing precision levels, it is important to truncate rather than round the easting and northing values to ensure the more precise polygon will remain within the boundaries of the less precise polygon. (In some cases, squares adjacent to a Grid Zone Junction (GZJ) are clipped, so polygon is a better descriptor of these areas.) The number of digits in the numerical location must be even: 0, 2, 4, 6, 8 or 10, depending on the desired precision. When the term 'grid square' is used, it can refer to a square with a side length of 10 km (6 mi), 1 km, 100 m (328 ft), 10 m or 1 m, depending on the precision of the coordinates provided.
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