Where is utm




















Care should be taken so that stating the hemisphere by the use of N north or S south after the zone number not to be confused with interpretation of N or S as latitude band letters. Outdoors guide books sometimes specify UTM coordinates in an abbreviated format when referring to a particular map of an area.

The first half of the number refers to the easting and the second half to the northing coordinate of a location. Since each easting or northing coordinate is a base 10 number, the right-most digit is the ones meter place; moving left next digit is the 10s meter place, third digit from left is the s meter digit and so on.

A complete UTM coordinate including all the digits, such as 12S mE mN, specifies the location of a point within a 1m by 1m square. When abbreviating a UTM coordinate, the ,s digit sixth digit from right and the ,s digit seventh digit from right are omitted. Then depending on the desired accuracy, the s, 10s, or ones digit is added to each easting and northing coordinate.

It is possible to define a location within m, m, or 1m. Keep in mind that no rounding of numbers takes place during truncation. To abbreviate 12S 5 65 mE 43 25 mN coordinate, the left-most 5 ,s digit from easting is omitted along with left-most 4 and 3 from northing ,s and ,s digit. The grid reference can then be stated as: GR defining a m x m square accurate to within m ; GR defining a m x m square; or GR defining a 10m x 10m square.

A 10 digit grid reference defines a 1m x 1 m square similar to the complete UTM coordinate: GR The six digit and eight digit grid reference formats are used more commonly. There are some advantages in using UTM coordinate system in comparison to latitude and longitude coordinates. In the UTM coordinate system, grid squares are the same size and shape throughout the map. In contrast, in the geographic coordinate system the distance represented by one degree or minute or second of longitude varies with latitude, therefore the units of measure do not remain constant across the globe.

The distances measured in degrees or minutes of longitude can not be compared at different latitudes. In UTM all measurements are done in meters. Coordinates are always positive and there is no need for N, E, W, S designations. There are no conversion between formats, such as between decimal and DMS.

Coordinate values of a point identify its position within the familiar Cartesian coordinate system. Coordinates within a zone can be directly added to each other and subtracted from each other. Therefore calculation of distances, directions and areas can be performed much more conveniently in comparison to geographic coordinate system. UTM is not suitable for areas that span more than a few zones since distortion and error increases when moving farther from the zone for which the projection is defined.

When working across zone boundaries multiple coordinate systems must be used. Coordinates in adjacent zones do not have a mathematical relationship. Large scale maps usually include the coordinates of the adjacent zones each zone is extended into its neighbor when a zone boundary falls within the map, that is more than one zone or portion of are shown on the map.

When a feature or desired locations fall into two zones, coordinates can be measured and stored consistently by using the same grid system.

Some other methods to address the zone boundary problem in UTM include: using a different zone width for the desired areas e. The last three methods allow for merging of data, analysis and storage within the GIS database. A coordinate system may be based on different datums. Different maps may refer to different datums, or the datum referenced by the GPS receiver may not correspond to the one for the map.

Example of map datum and coordinate conversion. Transferring coordinates between map versions, GPS and map or digital and paper maps might cause errors in location of coordinates due to the mismatch of datums. For example transferring coordinates of a trail junction from a map based on NAD 27 datum to a GPS that is set to WGS 84 datum may result in the GPS showing the location of the trail junction couple hundred meters off from the actual location.

It is important to state the datum when working with geographic data. Guidebooks usually specify the datum for the coordinates they provide.

The datum in GPS receivers can be set to correspond to the desired map's datum. The datum is printed on the margin of topographic maps, sometimes along with information for conversion of coordinates between two different datums by addition to or subtraction from northing and easting values; such as the example to the right.

UTM gridlines are usually shown on the map, or ticks are marked on the margins of the map. The tick marks can be connected by the use of a straight edge to produce gridlines. Depending on the scale of the map, the distance between grid lines may differ. The grid interval is usually indicated on the map margin. The ground distance of the grid interval can also be measured by the use of the map scale. Gridlines or ticks near the corners of the map are designated with full coordinate values.

Abbreviated values, called principal digits two larger numbers , are usually used to label the other grid lines. To find the UTM coordinate of a point, "read right up". The numbers designating the vertical gridlines at the bottom or the top of map are the easting values. The numbers to the sides of the map labeling horizontal lines are the northing values. In the map example below, grid lines are m apart. That is each grid square is m xm. To find the easting of point A, value of the nearest grid line to the left west of the point is found.

It's aligned so that vertical grid lines are parallel to the center of the zone, called the central meridian. UTM grid coordinates are expressed as a distance in meters to the east, referred to as the "easting", and a distance in meters to the north, referred to as the "northing". UTM easting coordinates are referenced to the center line of the zone known as the central meridian. The central meridian is assigned an easting value of , meters East. Since this ,m value is arbitrarily assigned, eastings are sometimes referred to as "false eastings".

UTM northing coordinates are measured relative to the equator. For locations north of the equator the equator is assigned the northing value of 0 meters North. To avoid negative numbers, locations south of the equator are made with the equator assigned a value of 10,, meters North.

Some UTM northing values are valid both north and south of the equator. In order to avoid confusion the full coordinate needs to specify if the location is north or south of the equator. The UTM projection minimizes distortion within that zone. So this means that when you want to show features in several UTM zone, it starts becoming a poor choice of map projection. Distortion is small near the central meridian, and as you move away it worsens.

So this makes it most fitting for narrow regions and not well-suited for world maps. Just like every map projection, the Universal Transverse Mercator has its strength and weaknesses. It is up to the map-maker to determine what projection is most favorable for its purpose.

The transverse Mercator map projection is an adaptation of the standard Mercator projection which flips the cylinder 90 degrees transverse. This gives cartographers a map to work with always in meters. The Universal Transverse Mercator is horrible for small-scale less-detailed maps like world atlases and perfect for mapping narrow regions.

UTM system, because of the distortions in each zone, with movement away from the central merdian seems to be of limited use for cadastral and engineering surveying. Why then is it being used by surveyors and allied specialists, while there are other projections -conical, orthogonal- and others.

Take a look at compromise map projections. Since a UTM zone is a projection onto a strip of a cylinder, which is flattened out to a planar strip, grid north cannot be true north except at the central meridian.

Consider this: For each zone, the central meridian passes through the North and South Poles. The amount of deviation increases with distance from the central meridian.



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