Differences between the three systemsderive mostly from redetermination of station locations rather than differences in the datum. The most modern datums (jars my Latinist sensibilities since the plural of datumin Latin is data, but that has a different meaning to us) are NAD83 andWGS84. Also, you are very unlikely tofind UTM grids based on any of the earlier projections. The top threeare based on worldwide data and are truly global. The earth isn't perfectly round, it isn't even a perfect ellipsoid, and slightly differentshapes work better for some regions than for the earth as a whole. The latitude of F is called the footprint latitude.įP = E = grid distance from central meridianĬ = convergence of meridians = angle between true and grid northĪnother thing you need to know is the datum being used: Datumĭon't interpret the chart to mean there is radical disagreement about theshape of the earth. Or better yet, a Javascript page.į = foot of perpendicular from P to the central meridian. This will get very complicated, but themath, although tedious, is only algebra and trigonometry. It would sure benice if someone wrote a spreadsheet to do this. (Before satellites, observing thosedifferences was a principal method for determining the exact shape of theearth.) Converting Latitude and Longitude to UTM For other latitudes multiply by cos(lat).Distances for degrees, minutes and seconds in latitude are very similarand differ very slightly with latitude. 366 minutes = 22 seconds, so the final result is 30 degrees 15 minutes 22secondsĪ degree of longitude at the equator is 111.2 kilometers. Use only the whole number part of mm in the final result. Here ff =the fractional part of a decimal degree. (dd + mm/60 +ss/3600) to Decimal degrees (dd.ff)ĭd = whole degrees, mm = minutes, ss = secondsĮxample: 30 degrees 15 minutes 22 seconds = 30 + 15/60 + 22/3600 = 30.2561ĭecimal degrees (dd.ff) to (dd + mm/60 +ss/3600)įor the reverse conversion, we want to convert dd.ff to dd mm ss. (arXiv:1002.1417) Converting Between Decimal Degrees, Degrees, Minutes and Seconds, andRadians Karney (2010) Transverse Mercator with an accuracy of a few nanometers. Each has advantages anddisadvantages. These have been entirely superseded by Charles F.
#UTM CONVERSION MANUAL#
ArmyTechnical Manual TM 5-241-8 (complete citations below).
#UTM CONVERSION PROFESSIONAL#
GeologicalSurvey Professional Paper 1395 and U. Previously, the two basic references for converting UTM and geographic coordinates wereU.S. Also, old World War II era maps of Europe apparently used a single gridfor all of Europe and grids in some areas are wildly tilted with respect tolatitude and longitude. I saw US military maps of Germanyshift their UTM grids by about 300 meters when a more modern datum was used forthe maps. This means that different maps will have different grids depending on thedatum used (model of the shape of the earth). UTM grids, on the other hand, are created by laying a square grid on theearth. But there is no way to determine your UTM coordinatesexcept by calculation. If you can see the stars andhave a sextant and a good clock set to Greenwich time, you can find yourlatitude and longitude. Latitude is determined by the earth's polar axis.Longitude is determined by the earth's rotation. I get enough inquiries on this subject that I decided to create a page forit.Ĭaution! Unlike latitude and longitude, there is no physical frame ofreference for UTM grids. Help! My Data Doesn't Look Like A UTM Grid! New! Javascript-Convert Between Geographic and UTM Coordinates Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay Converting UTM to Latitude and Longitude (Or Vice Versa)
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