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GeoHack

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GeoHack is a modified version of map sources from Egil Kvaleberg's gis extension. It is designed to do simple HTML replacements of a template on Wikipedia and serve it to the client. It is used by Wikipedia to provide links to various mapping services, when a user clicks on a link with geographical coordinates.

Different layout designs for GeoHack are listed on w:Template:GeoTemplate/sandbox.

Query

language

The requested language version (e.g., language.wikipedia.org), falls back to English if the template page does not exist.

pagename

The full title of the referring article. If not supplied, GeoHack will attempt to read the values from the HTTP referer.

params

Coordinates, optionally followed by other location-related parameters (underscore-separated, in a key:value fomat). Example: 1.292836_N_103.856878_E_type:landmark_dim:500

The coordinates are in one of the formats D_M_S_N_D_M_S_E, D_M_N_D_M_E, D_N_D_E, or D;D where D is degrees, M is minutes, S is seconds, and NS/EWO are the directions. Decimal numbers are accepted, especially for the last position.

TODO Document me: boxed range syntax D_N_D_E_to_D_N_D_E

Restrictions:

  • Should be compatible with MediaWiki titles: a 255 byte length limit, < > [ ] | are invalid, and spaces and underscore are treated the same.
  • & causes problems if it not percent encoded in the URL.
  • Avoid non-ASCII characters, as some browsers incorrectly handle copying and pasting.
  • Avoid the equal sign (=) since it causes issues with unnamed template parameters (e.g., {{Coord}})
  • The characters & < > " are escaped in the HTML to prevent exploits.
default
Default scale: for use in templates, is overridden by dim:, scale:, type: parameters.
dim
The size of the object in meters.
globe
Specify a different globe, defaults to Earth. The Argument value is used for the subpage name, e.g., globe:moon will load Template:GeoTemplate/moon.
page
(disabled) Specify a subpage for map sources.
region
(deprecated) The ISO 3166 code with an optional subdivision to highlight region specific services, see Section codes below. If not supplied, GeoHack will attempt to find the region using the coordinates.
scale
Set the relative map scale as 1:N. The OGC's "standard rendering pixel size" of 0.28 mm × 0.28 mm (90.7 dpi) is assumed and derived for all size calculations. Since the actual value can vary significantly (e.g. iPhone 4) it is recommended to use the display independent dim:.
type
The following are types GeoHack recognizes along with the calculated default scale.
TODO Provide definitions for each type.
type: ratio m / pixel {scale} {mmscale} {span} {altitude} {zoom} {osmzoom}
country, satellite 1 : 10,000,000 3528 10000000 10000000 10.0 1430 1 5
state 1 : 3,000,000 1058 3000000 4000000 3.0 429 3 7
adm1st 1 : 1,000,000 353 1000000 1000000 1.0 143 4 9
adm2nd (default) 1 : 300,000 106 300000 200000 0.3 42 5 11
adm3rd, city, mountain, isle, river, waterbody 1 : 100,000 35.3 100000 100000 0.1 14 6 12
event, forest, glacier 1 : 50,000 17.6 50000 50000 0.05 7 7 13
airport 1 : 30,000 10.6 30000 25000 0.03 4 7 14
camera, edu, pass, landmark, railwaystation 1 : 10,000 3.53 10000 10000 0.01 1 8 15
zoom
Deprecated Provided for compatibility with the Dutch maps.asp software. The scale is calibrated differently (SCALE = POWER(2, 12 - ZOOM) * 100 000, roughly equivalent to {osmzoom}) and conflicts with the replacement variable {zoom}

project

Request for a different project. If requesting the OpenStreetMaps (project=osm) page it will retrieve it from a template on meta: http://meta.wikimedia.org/wiki/Template:GeoTemplate/osm

title

Set this if the page is not an appropriate title, such as when referring to a location in the article such as a particular curve on a road.

Replacement variables

WGS84 Positioning
  • {latdegdec}, {londegdec} - Decimal degrees
  • {latdegdecabs}, {londegdecabs} - Absolute decimal degrees (no negative)
  • {latdeground}, {londeground} - Rounded integer degrees
  • {latdegroundabs}, {londegroundabs} - Rounded absolute
  • {latdeg_outer_abs}, {londeg_outer_abs} - Absolute integer degrees rounded up
  • {latdegabs}, {londegabs} - Absolute integer degrees
  • {latantipodes}, {longantipodes} - Antipodes of {latdegdec}, {londegdec}
  • {londegneg} - The negative of {londegdec}
  • {latdegint}, {londegint} - Integer degrees (floored)
  • {latmindec}, {lonmindec} - Decimal minutes
  • {latminint}, {lonminint} - Integer minutes
  • {latsecdec}, {lonsecdec} - Decimal seconds
  • {latsecint}, {lonsecint} - Integer seconds
  • {latNS}, {lonEW} - Direction of absolute integer degrees
UTM Positioning
  • {utmnorthing}, {utmeasting}, {utmzone}
  • {utm33northing}, {utm33easting}
Ordnance Survey Grid Positioning
  • {osgb36ref}
  • {osgb36northing}, {osgb36easting}
CH1903 Positioning
  • {ch1903northing}, {ch1903easting}
Scaling
name used by internal conversion units notes
{scale} Virtual Globe Use scale: or from dictionary look using type: value
{mmscale} Multimap Dictionary-like lookup
{altitude} MSN Maps (Archived 2008-05-16 at the Wayback Machine), Fourmilab, Swissinfo int( scale * 143/1000000 ), [1, infinity]
{zoom} MapQuest, Gule Sider int(18.0 - log(scale)), [0,9]
{osmzoom} OpenStreetMap, Live Search Maps 18 - ( round(log(scale,2) - log(1693,2)) ), [2, 18] OSM zoom level
{span} Google Maps, WikiMapia scale * 1.0 / 1000000 degrees/nautical miles FIXME calibration;
never is correct as span is tied to the view port size not scale
[1] (Archived 2007-07-08 at the Wayback Machine)
Geographical features
  • {type}, {region}, {globe} - The parameters from the params. Globe is deprecated with the implementation of subpages for bodies.
Coordinate title
  • {pagename} - Underscore page name, as given by the pagename or determined by the HTTP referrer.
  • {title} - Title of the location as given by title, if not specified then falls back to {pagename} with the underscore replaced with spaces.
  • {pagename_gmaps} - work around for google maps, will be replaced by {pagenamee}
Misc./Not fully implemented
  • {page} - Deprecated
  • {geocountry} - same as region:
  • {geoa1} - Characters 4 to 8 of region; Uppercased
  • {lang} -likely to change
  • {params} - content from params=

Section codes

If the region is supplied or determined then GeoHack moves the section to the placeholder: 

<div id="GEOTEMPLATE-LOCAL"></div>

The region sections are wrapped in the divs where XX of the id is the ISO 3166-1 alpha-2 code: 

<div id="GEOTEMPLATE-XX">
...
</div>

A surrounding div can style this section or the local div can provide only local links. To save bandwidth and simplify the REGIONS div will be removed if a local section is found. 

<div id="GEOTEMPLATE-REGIONS">
...
</div>

Synchronizations

Due to issues affecting the squid server implementation on WMF servers, pages are cached longer than they should. This worked around requesting a different URL every hour.

JavaScript

For user modifications and development, JavaScript is loaded from the local language's MediaWiki:GeoHack.js page. See English Wikipedia for an example.

Embed maps

GeoHack for Firenze, in Italian

Wikimedia Maps (maps.wikimedia.org) can be embedded in the tool with two edits that will not change any content or code on the source wiki: see example MediaWiki:GeoHack.js and GeoTemplate.

The Russian and Italian Wikipedias did so in November–December 2015, see example screenshot.

Nice URLs

A URL rewrite.script has been installed to allow shortening of URL. The example below illustrates the parts that are changed or removed. 

https://geohack.toolforge.org/geohack.php?language=en&params=40.7;-74_type:city(8000000)&pagename=New_York_City
https://geohack.toolforge.org/en/40.7;-74_type:city(8000000)?pagename=New_York_City

It is also compatible with the {{fullurl:}} parser function

{{fullurl:toolforge:geohack/en/52 30 N 13 23 E type:city(3431700)|title=Berlin}} →

https://iw.toolforge.org/geohack/en/52_30_N_13_23_E_type:city(3431700)?title=Berlin

Note it is not necessary to supply pagename as this can often be derived from the referer, see pagename above. 

# URL Rewrite script for GeoHack
match URL into $ with ^/~geohack/([a-z-]{2,12})/([^=]*)([&?]([a-z]+=.*)$|$)
if matched then
        set URL = /~geohack/geohack.php?language=$1&params=$2&$4
endif

Note, for compatibility reasons, "?" parameters must contain "=" values.

Source code

# Clone the current version:
git clone https://bitbucket.org/magnusmanske/geohack.git

# Commit changes:
git commit -a -m "commit summary"

# Update the live installation:
become geohack
cd public_html/; git pull

See also

Geo-data projects

Maintainers

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