Or better yet, a Javascript page.į = foot of perpendicular from P to the central meridian. This will get very complicated, but the math, although tedious, is only algebra and trigonometry. It would sure be nice if someone wrote a spreadsheet to do this. (Before satellites, observing those differences was a principal method for determining the exact shape of the earth.) Converting Latitude and Longitude to UTM Distances for degrees, minutes and seconds in latitude are very similar and differ very slightly with latitude. For other latitudes multiply by cos(lat). 366 minutes = 22 seconds, so the final result is 30 degrees 15 minutes 22 secondsĪ 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. Converting Between Decimal Degrees, Degrees, Minutes and Seconds, and Radians Some extremely tiny terms that will not seriously affect meter-scale accuracy have been omitted. Here the USGS publication is the only game in town. In defense of the USGS, their notation is constrained by space, and the need to be consistent with cartographic literature and descriptions of several dozen other map projections in the book.įor converting UTM to latitude and longitude, however, the Army publication has formulas that involve latitude (the quantity to be found) and which require reverse interpolation from tables. Its notation is more consistent and the formulas more clearly laid out, making code easier to debug. Each has advantages and disadvantages.įor converting latitude and longitude to UTM, the Army publication is better. Army Technical Manual TM 5-241-8 (complete citations below). Geological Survey Professional Paper 1395 and U. The two basic references for converting UTM and geographic coordinates are U.S. Also, old World War II era maps of Europe apparently used a single grid for all of Europe and grids in some areas are wildly tilted with respect to latitude and longitude. I saw US military maps of Germany shift their UTM grids by about 300 meters when a more modern datum was used for the maps. This means that different maps will have different grids depending on the datum used (model of the shape of the earth). UTM grids, on the other hand, are created by laying a square grid on the earth. But there is no way to determine your UTM coordinates except by calculation. If you can see the stars and have a sextant and a good clock set to Greenwich time, you can find your latitude and longitude. Longitude is determined by the earth’s rotation. Latitude is determined by the earth’s polar axis. I get enough inquiries on this subject that I decided to create a page for it.Ĭaution! Unlike latitude and longitude, there is no physical frame of reference for UTM grids. Help! My Data Doesn’t Look Like A UTM Grid! New! Javascript-Convert Between Geographic and UTM Coordinates Steven Dutch, Natural and Applied Sciences, University of Wisconsin – Green Bayįirst-time Visitors: Please visit Site Map and Disclaimer. Converting UTM to Latitude and Longitude (Or Vice Versa)
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