User:EncMstr/Coord

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Questions[edit]

  • I want to enter coordinate data, but am confused by {{coord}}. Can you explain in a simpler way than the documentation does?
  • When will the W icon show up on Google Maps? I put the coordinates in an article several weeks ago...

Answers[edit]

The template {{coord}} takes three kinds of parameters:

  1. latitude and longitude which give a position somewhere on a globe
  2. attributes for the geographical point
  3. display options

Here are two examples which demonstrate most features:

  1. {{coord|61|9|47.16|N|149|58|19.56|W|type:landmark_globe:earth_region:US-AK_scale:150000_source:gnis|name=Kulis Air National Guard Base}} displays 61°9′47.16″N 149°58′19.56″W / 61.1631000°N 149.9721000°W / 61.1631000; -149.9721000 (Kulis Air National Guard Base)
  2. {{coord|61.1631|-149.9721|type:landmark_globe:earth_region:US-AK_scale:150000_source:gnis|display=inline,title|name=Kulis Air National Guard Base}} displays 61°09′47″N 149°58′20″W / 61.1631°N 149.9721°W / 61.1631; -149.9721 (Kulis Air National Guard Base)Coordinates: 61°09′47″N 149°58′20″W / 61.1631°N 149.9721°W / 61.1631; -149.9721 (Kulis Air National Guard Base)

Both specify the same position and provide the same attributes. There are minor differences in how data is formatted, but they otherwise function the same.

Latitude and longitude[edit]

The first usage gives the coordinate as degrees, minutes, and seconds. With "dms" format, one has to specify North/South and East/West. I think the latitude has to be first; I've never seen a successful usage with longitude first. Minutes and seconds are similar to clock times in their interrelationships. One could write John will be there in 2 minutes and 62 seconds (or 2:62). It's unambiguous and has clear meaning. But weird. We expect times to be normalized so that minutes and seconds are less than 60. So we prefer 3 minutes and 2 seconds (or 3:02). It's the same way with coordinates: 61° 8′ 107.16″ N, 149° 58′ 19.56″ W specifies the same point, but seconds 60 or greater is weird. Such a thing in an article could well be a symptom indicating some error is present: maybe a transcription error, or a reference which uses implied decimal points wasn't interpreted correctly.

Alternatively, a coordinate can be succinctly expressed in fractional degrees (called "dec" notation), just as the coordinates above provide fractional seconds. Example 2 not only gives just two numbers, but it uses the sign of the numbers to indicate NSEW. North and east are positive; south and west are negative, just like in Cartesian geometry.

It is not necessary to be so precise. For large objects, it is recommended that less precision be given. For example, Oregon is located at (45 N, 120.5 W), a point approximately in the middle. For objects about the size of large cities, degrees and whole minutes are plenty: {{coord|45|31|N|122|41|W}}.

Attributes[edit]

The rather inscrutable 63 characters beginning with type and ending with gnis is a single template parameter: It encodes a variety of information about the geographical point; all of it is optional, but at least some is nice to have. There must be only one such template parameter; they can't be separated: {{coord|12.34|56.78|type:waterbody|region:US-MN}} is invalid because two template parameters contain attributes.

The mapping services selection page (GeoHack)—the URL the coordinate links to—in particular uses a specified region to include and exclude appropriate region-specific mapping services. Other parameters are helpful for re-users of coordinate data, especially automatically extracted users such as Google Maps and Google Earth.

The attributes are in a glommed together geo parameter parameter. It's a peculiar way to specify parameters—even for computer geeks: they could have used multiple named parameters, or at least separate the glommer with commas or semicolons. But once you understand the delimiter for the glommer parameter is an underscore, it's quite easy to use. The examples have five fields:

  • type:landmark
  • globe:earth
  • region:US-AK
  • scale:150000
  • source:gnis

The order of these doesn't matter.

Each parameter has a well-defined set of valid values. Well, except scale which works with almost any value. It specifies the preferred map scale to be displayed: 150000 means 1:150,000 (one to a hundred and fifty thousand). That is, one inch on your monitor is a scale of 2.367 miles (one inch is 150,000 inches = 12,500 feet = 2 miles, 1940 feet). Clearly the metric system is less obtuse here: 1:150,000 means 1 centimeter represents 150,000 cm or 1500 m. If no scale is specified, and there is no type (see below), 1:300,000 is used.

The globe specifies the Earth. But one might specify a position on the Moon, Venus, Mars, etc. Since Earth is assumed, globe:earth rarely appears in actual usage. I'm told that non-Earth globes are not yet implemented.

The type specifies the general classification of the object at the point. There appear to be some older undocumented values in widespread use, such as town. Here are the supported types, with the most frequently used types at the top.

  description scale
type:landmark cultural landmark, building, attraction, etc. 1:10,000
type:city(pop) city, town, or village of given population (no blanks or separators) 1:30,000 ... 1:300,000
type:city city, town, unincorporated area 1:100,000
type:mountain peaks, mountain ranges 1:100,000
type:mountain(elev) peaks, mountain ranges with the peak elevation in meters (no blanks or separators) 1:100,000
type:isle isles, islands 1:100,000
type:waterbody bays, lakes, reservoirs, lochs, lagoons, estuaries, inland seas, etc. 1:100,000
type:edu schools, colleges, universities 1:10,000
type:pass mountain passes 1:10,000
type:airport airfields, airports, aerodromes, heliports 1:30,000
type:river rivers, canals (place point at the mouth) 1:100,000
type:forest forests, woodlands 1:50,000
type:glacier glaciers, snowfields, ice caps 1:50,000
type:railwaystation railroad stations of any train, subway, funicular, etc. 1:10,000
type:adm1st first level administrative unit of country (province, state) (see table) 1:1,000,000
type:adm2nd second administrative unit of country (see table) 1:300,000
type:country for the location of a country 1:10,000,000
type:satellite geostationary satellites 1:10,000,000


Region is a useful parameter which aids good online mapping. Its format is region:XX-YY or region:XX where 'XX' is the two character country or region code surrounding the point. 'YY' is a subdivision of the region code. All the values can be found at ISO 3166-1. For the US, give US or US-YY where YY is the postal service state code (AK = Alaska, MO = Missouri, MS = Mississippi, etc. A full list is on ISO 3166-2:US) Other English-speaking region codes are:

XX-YY region
AU Australia
BZ Belize
NZ New Zealand
GB Great Britain which includes Scotland, Wales, and Northern Ireland (not UK!)
CA Canada
CA-AB Alberta, Canada
CA-BC British Columbia, Canada
CA-MB Manitoba, Canada
CA-NB New Brunswick, Canada
CA-NL Newfoundland and Labrador, Canada
CA-NS Nova Scotia, Canada
CA-NT Northwest Territories, Canada
CA-NU Nunavut, Canada
CA-ON Ontario, Canada
CA-PE Prince Edward Island, Canada
CA-QC Quebec, Canada
CA-SK Saskatchewan, Canada
CA-YT Yukon Territory, Canada

I'm not sure what the primary purpose of source is, but it is handy for noticing "reference loops". For example, if a German-language article has a coordinate and gives source:enwiki (meaning English Wikipedia), then while correcting the English version of the article, it would be best to check the primary source of the coordinate rather than copy the German value. Of course if a German language article about a place in Germany/Switzerland/Austria/etc. gives a coordinate, it would be proper to use the coordinate value and give source:dewiki For U.S. points, source:gnis is the authoritative reference and can be looked up at http://geonames.usgs.gov/pls/gnispublic/. See the GNIS article for an explanation. If you determined a coordinate by looking at a map and satellite photo, it might be appropriate to give the source as the database, whether MapQuest, Google Maps, TopoZone, etc. There are numerous specifics for additional possibilities in the {{coord}} documentation.

Additional details about the glommed together geo parameter parameter are at template:coord#Coordinate Parameters.


Besides the 5 primary attributes above, there are a few more parameters which have been proposed or are recognized by some of the coordinate processing utilities.

  • dim:n
  • elevation:n

Each of these is followed by a number, a measurement based on meters (metric measure).

The dim parameter is already in widespread use on the German Wikipedia—it is implemented on English Wikipedia July 2009 (see WT:GEO for updates). It specifies the longest dimension of the object in metric measure to help autoscaling map displays provide a workable view. It also provides a hint as to how much coordinate precision make sense. For example, the coordinate for a city one mile wide and four miles long would be geocoded with dim:6.4km or dim:6400 since 4 miles is the longer dimension which is a little more than 6 kilometers. Mill Ends Park uses dim:0.61 since it is 61 cm in diameter.

The elevation parameter provides the elevation of the object or terrain above mean sea level—the normal reference for topographic data—measured in meters. This is used by data harvesters for generating map data based on Wikipedia's data. For example, if Paris were coded with this parameter, elevation:35. For the second highest mountain—K2—it would be elevation:8611. A trickier example is the Cobb hotspot, a region on the floor of the Pacific ocean at elevation:-1450.

Display options[edit]

These options are named parameters, which contrasts all the above parameters which are unnamed: that is, no equal sign is used—the sequence the parameters appear provides context. For example 61.1631 (above) is positioned as a latitude.

There are only three display options:

  • display=inline,title or display=inline or display=title
  • name=name of point, (if not the article name)
  • format=dec or format=dms

These are tersely explained at template:coord#Usage.

Display=[edit]

Display=title says only display the coordinate at the article's upper-right corner and not where the template appears. Display=title,inline and Display=inline,title say to display at the article's upper-right and the point where the template appears. If the display= parameter is omitted, it's the same as display=inline. (Conversely, {{coord| ...|display=inline}} demonstrates unnecessary typing; see no op.)

Name=[edit]

Name isn't ordinarily used, except

  • in an article oddly named for disambiguation reasons, or
  • in an article with multiple coordinates.

For an article listing multiple coordinates, another useful template is {{GeoGroupTemplate}}. This links to a map showing all the coordinates in an article. Click on Map of all coordinates at the end of the section Mount Hood#Glaciers. Notice how each point contains a name which can be displayed by clicking on the markers, or the glacier name links at left.

Format=[edit]

The display options format=dec and format=dms probably have little practical use. One of the cool features of coord is that a user, such as yourself, can choose to have all coordinates displayed in either format—or both—no matter how the article was written by modifying your Wikipedia style sheet. See Template:Coord#Display for details.

Google extraction[edit]

As for appearing on Google Maps and Google Earth, Google takes a snapshot of Wikipedia every few months and selects data from that. Google's explanation is here.

Only articles using {{coord}} with display=title (or display=inline,title) are extracted.

Notes[edit]

There are several nuances above which don't follow the guidelines at WP:GEO:

  • The position given is overly precise for such a facility. The accuracy demonstrated is suitable for a small object, such as a fountain or gravestone.
  • I didn't verify that gnis contains this coordinate, so attribution to gnis isn't necessarily true.

Hints[edit]

  • A useful feature I recently stumbled upon: click on a coordinate's globe icon to see a handy pop up zoomable map which shows the general location of the feature.
  • Besides a number of mapping and satellite image services, the GeoHack page (the map utility selection page generated by clicking on the URL portion of a coordinate) has a huge number of transformations and extractions of the data. Examples include finding nearby points from other Wikipedia pages (under Systems with Wikipedia data), finding nearby prehistoric sites (under History near the bottom), and nearby photographs on Flickr.