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Incubator escapee wiki:WikiProject Geographical coordinates
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==Implementation details== ===Coordinate templates=== There are two ways of specifying coordinates: # {{tlx|coord}} – Accepts multiple data formats and supports a style sheet preference for display format, plus a [[Geo (microformat)|Geo microformat]]. <code>Coord</code> may be placed anywhere in the article source text, inline, with prose text. For example "<code>Mount Everest is at <nowiki>{{coord|27|59|16|N|86|56|40|E}}</nowiki></code>", which displays as "Mount Everest is at {{coord|27|59|16|N|86|56|40|E}}". To display coordinates at the page's top, near the article's title, in a skin-dependent way, use <code>display=title</code> (see example at [[Krasnoyarsk hydroelectric dam]]). To display both inline and top, use <code>display=inline,title</code>. # Infoboxes – Many [[:Category:Infobox templates|infobox templates]] for places have a parameter, typically {{para|coordinates}}, for specifying a place's coordinates. The template internally uses {{tl|coord}} and may therefore also display in the title area. See [[Template:Infobox Settlement]] and [[Template:Infobox Mountain]] for documentation, or, usage examples at [[Los Angeles, California|Los Angeles]] and [[Mount Everest]]. (Before September 2008, there was a widely-used family of templates of the form ''coor ...''. These are deprecated and have been replaced by {{tl|coord}}. For an overview of choices: [[/comparison|WikiProject Geographical coordinates/comparison]].) ====Parameters==== Following the geographical coordinate, further parameters can optionally be supplied, separated by underscores. This helps display suitable map resources (see [[Template:GeoTemplate]]), and will help [[m:Category:Wikimaps|Wikimaps]] become fully functional. [[User:EncMstr/Coord|For example:]] :{{tlx|coord|61.1631|-149.9721|type:landmark_globe:earth_region:US-AK_scale:150000_source:gnis|5=name=Kulis Air National Guard Base}} displays {{coord|61.1631|-149.9721|type:landmark_region:US-AK_scale:150000_source:gnis|name=Kulis Air National Guard Base}} It has * type:landmark * globe:earth * region:US-AK * scale:150000 * source:gnis ===== type:''T'' ===== {{shortcut|WP:COORD TYPE}} {{/type:}} ===== dim:''D'' ===== {{/dim:}} ===== scale:''N'' ===== {{shortcut|WP:COORD SCALE}} {{/scale:}} ===== region:''R'' ===== {{shortcut|WP:COORD REGION}} {{/region:}} ===== globe:''G'' ===== {{/globe:}} ===== source:''S'' ===== {{shortcut|WP:COORD SOURCE}} {{/source:}} ==== Name ==== {{tl|coord}} takes <code>|name=''name''</code> If an article contains several ''display=inline'' coordinates, each of these may be supplied with a unique ''name''. This name will be used to display the coordinate on the [[:meta:WikiMiniAtlas|WikiMiniAtlas]], and will cause the template to emit an [[hCard]] [[microformat]] using that name, ''even if used within an existing hCard''. Do not use when the name is that of a person (e.g for a gravesite), as the generated hCard would be invalid. Also, do not use square brackets in names. ==== <span id="Display">Display preferences</span> ==== {{UF-coord-classes}} ==== Format ==== * <code>format=dec</code> will reformat the coordinates to <span style="text-decoration:underline;">decimal degrees</span> for all readers. * <code>format=dms</code> will reformat the coordinates to <span style="text-decoration:underline;">degrees | minutes | seconds (dms)</span> format for all readers. ====Creating new templates==== When creating new templates or infoboxes, use {{tl|coord}}. Unless a template uses the coordinate data in another way, the {{tl|coord}} template should be the field value. For example, {{tl|infobox lake}} accepts <code><nowiki>coords = {{coord|45|N|6|E|type:waterbody}}</nowiki></code>. If coordinate data are used directly by a template, use the following parameter names for coordinates: {| |- | * lat_d * lat_m * lat_s * lat_NS || * long_d * long_m * long_s * long_EW |} A provision for accepting decimal coordinates is recommended. For example, allow <code>lat_d = 45.678 | long_d = -123.456</code> and omission of the remaining parameters. Where the [[United Kingdom]]'s [[Ordnance Survey]] grid references are used as the coordinates, use {{tlx|oscoor}}. For articles which have no coordinates, but need them, use {{tlx|coord missing}}. === Linear features === For ''draft'' guidance on, and examples of, coordinates for linear features (rivers, roads, bridges, tunnels, etc.), see [[Wikipedia:WikiProject Geographical coordinates/Linear]]. ===How to obtain geographical coordinates=== See [[Wikipedia:Obtaining geographic coordinates|Obtaining geographic coordinates]] ''See also:'' [[:Category:Articles needing coordinates]], [[:de:Wikipedia:WikiProjekt Georeferenzierung/Wikipedia-World/en#Maybe-Checker|Maybe-Checker]] ===Geodetic system=== All coordinates specified through {{tl|coord}} must be referenced to [[World Geodetic System|WGS84]], or an equivalent datum. WGS84 is required for some of the conversions done by the geohack extension. [[British national grid reference system|British national grid references]] of the Ordnance Survey use its own [[British national grid reference system|OSGB36]] datum, which is ''correct'' for use in national grid references; the correct transformations will automatically be applied when national grid coordinates are used in {{tl|oscoor}} tags. However, OSGB36 latitude/longitude coordinates should not be used anywhere in Wikipedia; please use WGS84 lat/long instead. ==={{anchor|Precision}}Precision guidelines=== {{shortcut|WP:OPCOORD}} Regardless of how coordinates are obtained, consider the precision specified in a Wikipedia article. Reliable secondary sources exist for some locations. ''Without a reliable source, the larger the object being mapped, the less precise the coordinates need to be.'' Cities must be specified with a precision of degrees, minutes and seconds to respect historical norms. When the [[#Which coordinates to use]] guideline is used, degrees, minutes and seconds or d.dddd are the default. To specify a particular point in the city, such as a building, generally requires precision down to degrees-minutes-seconds or d.dddd° if decimal degrees are used. In the case of objects such as fountains or statues, it may be necessary to use d°m's.s" or d.ddddd°. Higher precisions should be avoided, as they greatly exceed the accuracy of civilian GPS and online mapping services. (Using 4 m accuracy as an estimate for civilian GPS: Depending on the coordinates format and the latitude, the next-higher precisions exceed the accuracy by a factor of somewhere between 13 and 72.) A general rule is to give precisions approximately one-tenth the size of the object, unless there is a clear reason for additional precision. Overly precise coordinates can be misleading by implying that the object is smaller than it truly is. There is no set way to determine object size, and the boundaries of many geographical objects are not clearly defined or not readily available. The difference rarely affects the suggested coordinates precision, so a rough size estimate is usually adequate. However, it should be noted that object size is always linear (one-dimensional), not an area measurement. In the two most-used coordinate representations, degrees-minutes-seconds and decimal degrees, precision is, as a useful approximation, {| |- style="vertical-align:top;" | {| class="wikitable" style="text-align:right;" |+ Degrees-minutes-seconds format !Precision !Diff. at equator !Diff. at 30° !Diff. at 45° !Diff. at 60° |- |1°||111 km||96.4 km||78.7 km||55.7 km |- |1′||1.85 km||1.61 km||1.31 km||0.93 km |- |0.1′||185 m||161 m||131 m||93 m |- |0.01′||18.5 m||16.1 m||13.1 m||9.3 m |- |1′′||31 m||27 m||22 m||15 m |- |0.1′′||3.1 m||2.7 m||2.2 m ||1.5 m |} || {| class="wikitable" style="text-align:right; margin-left:20px;" |+ Decimal degrees format !Precision !Diff. at equator !Diff. at 30° !Diff. at 45° !Diff. at 60° |- |1°||111 km||96.4 km||78.7 km||55.7 km |- |0.1°||11 km||9.64 km||7.87 km||5.57 km |- |0.01°||1.1 km||964 m||787 m||557 m |- |0.001°||110 m||96.4 m ||78.7 m||55.7 m |- |0.0001°||11 m||9.64 m||7.87 m||5.57 m |- |0.00001°||1.1 m||96.4 cm || 78.7 cm || 55.7 cm |} |} Conversions: {{convert|1|km|mi|3}}, {{convert|1|m|ft|2}}, {{convert|1|cm|in|3}}; {{convert|1|mi|km|2}}, {{convert|1|ft|m|3}}, {{convert|1|in|cm|2}} The values in the table give distances in the east-west direction corresponding to a small change in longitude, at different latitudes. You can take the equator columns of the table as a rough guide to distances in the north-south direction that correspond to a small change in latitude, since they vary only a little bit at different latitudes. For simplicity, however, the latitude precision is commonly copied from that of the longitude. ====Precision tables==== {{shortcut|WP:COORDPREC}} The following tables show suggested coordinates precisions for various object sizes and latitudes. Refer to the preceding section for more information about coordinates precision. To use these tables: * Choose one of the tables depending on whether you want '''degrees-minutes-seconds''' format or '''decimal degrees''' format * Find the column that is closest to the latitude of your object * Find the row that is closest to the size of your object * Note the coordinates precision at the intersection of your row and column {{Collapse top|title=Usage example|bg=#daf0da}} Example: You want coordinates, in decimal degrees format, for Yosemite National Park, California, U.S. * The size of the object is roughly 70 km * [https://geonames.usgs.gov/apex/f?p=138:1:0::::: GNIS query] gives the Park's location, in decimal degrees, as: 37.8483188 (north latitude), −119.5571434 (west longitude) To solve: * Choose the '''Decimal degrees format''' table * Find the '''45°''' column; 37.8483188 is (slightly) closer to 45° than to 30° * Find the '''50 km''' row; 70 km is closer to 50 km than to 100 km * Note the precision at the intersection of row and column: d.d° * [[Rounding|Round]] to the selected precision: 37.8, −119.6 (This is a good example of a ''borderline case'', as the latitude is quite close to 37.5°, the midpoint between 30° and 45°. If the Park were a mere 25 miles to the south, you would use the '''30°''' column instead, yielding a different precision: d.dd°. You could opt for that precision instead, giving 37.85, −119.56. That's your call. But the table shows that ''more than'' two decimal positions would definitely be too precise for this case.) {{Collapse bottom}} <!-- BACKGROUND COLORS: #f2f2f2 - gray for the object size header columns (latitude header rows have this color by default) #ffe7e7 - pink for data cells #daf0da - blue-green for data cells --> {| |- style="vertical-align:middle;" | {| class="wikitable" style="text-align:left;" |+ Degrees-minutes-seconds format ! !0° !30° !45° !60° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''10 m''' |colspan="3" style="background:#f2f2f2; text-align:center;"|d° m' s.s" or d.ddddd° <sup>[note 3]</sup> |style="background:#ffe7e7;"|d° m' s.s" |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''50 m''' ||d° m' s.s" ||d° m' s.s" ||d° m' s.s" ||d° m' s.s" |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''100 m''' ||d° m' s.s" ||d° m' s.s" ||d° m' s.s" ||style="background:#daf0da;"|d° m' s" |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''500 m''' ||d° m' s" ||d° m' s" ||d° m' s" ||d° m' s" |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''1000 m<br>1 km''' ||d° m' s" ||d° m' s" ||d° m' s" ||d° m' s" |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''5 km''' ||d° m' s" ||d° m' s" ||d° m' s" ||style="background:#ffe7e7;"|d° m' |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''10 km''' ||d° m' ||d° m' ||d° m' ||d° m' |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''50 km''' ||d° m' ||d° m' ||d° m' ||d° m' |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''100 km''' ||d° m' ||d° m' ||d° m' ||d° m' |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''500 km''' ||style="background:#ffe7e7;"|d° m' ||d° ||d° ||d° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''1000 km''' ||d° ||d° ||d° ||d° |} || {| class="wikitable" style="text-align:left; margin-left:20px;" |+ Decimal degrees format ! !0° !30° !45° !60° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''10 m''' ||d.ddddd° ||d.ddddd° ||d.ddddd° ||d.ddddd° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''50 m''' ||d.ddddd° ||d.ddddd° ||style="background:#ffe7e7;"|d.dddd° ||style="background:#ffe7e7;"|d.dddd° |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''100 m''' ||d.dddd° ||d.dddd° ||d.dddd° ||d.dddd° |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''500 m''' ||d.dddd° ||d.dddd° ||style="background:#daf0da;"|d.ddd° ||style="background:#daf0da;"|d.ddd° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''1000 m<br>1 km''' ||d.ddd° ||d.ddd° ||d.ddd° ||d.ddd° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''5 km''' ||d.ddd° ||d.ddd° ||style="background:#ffe7e7;"|d.dd° ||style="background:#ffe7e7;"|d.dd° |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''10 km''' ||d.dd° ||d.dd° ||d.dd° ||d.dd° |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''50 km''' ||d.dd° ||d.dd° ||style="background:#daf0da;"|d.d° ||style="background:#daf0da;"|d.d° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''100 km''' ||d.d° ||d.d° ||d.d° ||d.d° |- style="background:#daf0da;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''500 km''' ||d.d° ||d.d° ||style="background:#ffe7e7;"|d° ||style="background:#ffe7e7;"|d° |- style="background:#ffe7e7;" |style="background:#f2f2f2; text-align:right; padding-right:10px;"|'''1000 km''' ||d° ||d° ||d° ||d° |} |} #{{smaller|The tables are derived from the precision data at {{section link||Precision guidelines}}, above. As suggested there, they use a target resolution of one-tenth of the object size.}} #{{smaller|The tables are not perfect. Some cases will yield a precision that is different from what you would get by doing the math (including trigonometry) for that specific case. This is because it is impossible to represent all cases correctly in a usable tabular format. The tables provide the correct precision for a majority of cases. Any error should be limited to one level of precision (e.g., '''d° m'''' vs. '''d° m' s"''', or '''d.ddd°''' vs. '''d.dddd°'''), which is acceptable for the purposes of Wikipedia coordinates.}} #{{smaller|'''d.ddddd°''' is roughly three times more precise than '''d° m' s.s"'''.}} ====Mathematical formulas==== You can also calculate the kilometers per degree of longitude, ''k,'' using one of the following formulas (θ is the latitude, 6378.14 km is the [[Earth radius|equatorial radius]], and 6356.8 km is the polar radius): Accurate, assuming a [[spheroid]]: * <math>k = \frac{\pi}{180}\cos(\theta)\sqrt{\frac{(6378.14^2\cos\theta)^2+(6356.8^2\sin\theta)^2}{(6378.14\cos\theta)^2+(6356.8\sin\theta)^2}}</math> Approximate: * <math>k = 111.3\cos\theta\,</math> Equator to latitude 25° (north or south) * <math>k = 111.2\cos\theta\,</math> Latitude 30° to 40° * <math>k = 111.1\cos\theta\,</math> Latitude 45° to pole === Coordinates from other language versions (iwcoor) === {| class="wikitable" |- ! Import of coordinates from other wikis |- | * conversions are done based on external links to mapsources in other languages * the [[tools:~dispenser/view/File viewer#log:iwcoord-enwiki-Coord missing.log|iwlog]] determines primary coordinates for articles in other languages * in general, primary coordinates are imported to this wiki * coordinates are used to replace {{tl|coord missing}} with {{tl|coord}} with the parameter display=title * dms or decimal format is kept, format=dms can be added to decimal coordinates * negative coordinates followed by N or E are converted to positive coordinates followed by S or W * coordinates are not imported if: ** degrees are out of range (90°/180°) ** minutes or seconds >= 60 ** region doesn't start with [a-zA-Z] [a-zA-Z] ** type is not in [[Wikipedia:GEO#type:T|list]]. A few are corrected (e.g. village=>city, lake=>waterbody, dam=>landmark, island=>isle). coordinates with type:state are not converted. Numbers other than population are stripped. ** globe is present * scale is kept, zoom from nl: converted to scale. scale can be dropped if it's equivalent to the one determined by type * source is set to "xxwiki" (xx being the wiki the coordinates are imported from). An additional string can be added to differentiate one bot from others (e.g. "-x"). If source: is used in the other language, the previous element is added after a slash, e.g. source:gnis imported from xx: wiki => source:xxwiki-gnis * region is set to uppercase, type and scale to lowercase * other elements are discarded |- | Last updated: 16:02, 6 April 2009 (UTC) |}
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