Wikipedia:WikiProject Maps/Conventions/Gradient maps

This page provide conventions for the creation of gradiant maps.
Gradient maps are a light and basic visualisation of spacial areas and their associated values for a single thematic issue, by example the population density by country. Gradient maps need 3 key things: 1. a solidly sourced list of regions⇔values for one issue, 2. a map displaying these regions, 3. a sequential color ramp for legend. This style is conveniently derived from [location maps] style. This style purpose is to illustrate articles including a table of values by regions, thus giving an helpful visualization to understand the data within it's spacial and relational context.

Usage: These maps are final products, usually not reused to generate more complex maps.

Where: examples of gradiant maps can currently be found in the category Category:Maps_generated_with_GunnMap. When you create a such map, please tag your upload with Category:Gradient map.

Convention

Convention for location maps.

Subject	Colorimetry (RGB/hex)
Toponymes (names)	#000000 R:0 G:0 B:0
Border. Labels (country/state/province's name)	#646464 R:100 G:100 B:100
Subject's area (country, province)	#FEFEE9 R:254 G:254 B:233
Other areas part of the same political unity	#F6E1B9 R:246 G:225 B:185
Outside area	#E0E0E0 R:224 G:224 B:224
Coasts of lakes, rivers, seas, and hydronyms (Temporary coastlines, color and ratio: opacity:0.6;dasharray:4, 4;stroke-width:1;)	#0978AB R:9 G:120 B:171
Ocean, sea, lake (Temporary body, color and ratio: opacity:0.6;stroke-dasharray:4, 4;stroke-width:1;)	#C6ECFF R:198 G:236 B:255
Naming (upload): File:{Subject} per {Country or Area name in English} gradient map-YYYY.svg Note: all the subject, the areas, and the date (YYYY or YYYY MM DD) are critical.
Further needs: Legend: very need (otherwise the map is useless). Scale: not need. Projections: Equirectangular projection (except for extreme north or extreme south coutry.), please follow World6 and the location maps.</nowiki>
SVG template: if you need some labels, please use Image:Maps_template-en.svg which provide further label conventions.

Motivations

This location maps focusing on a subject being the basis of map making on wikipedia, a special attention is need for this set, to make it respect a chosen style.

Moreover, this maps are widely use with the {{Superimpose}} and {{Location map}} template, to notice the coordinates of a city, building, battle, etc. , accordingly, they are use in the infobox of many such articles, contributing to the harmonisation of the infoboxes look.

History and current work

History

Gradiant map are, from the beginning, and the center of wikipedia's maps creation. There have been in used "for ever", since they are logical solution to display data (table of values?) where each spacial area is associated with a given values. Most frequently on Wikipedia, a gradiant map is a one-theme worldmap displaying the countries of the word, where each country is assigned a given color according to the data available for this theme. By example GDP per capita by country, Population density per country. It can also go on lower levels, such as Population density per province in PRC.

Interesting technical issues

World gradient maps are better derived from File:BlankMap-World6.svg. For other areas of lower levels, the location maps are a first tool. For better svg's codes or automatization, QGIS and SVGSimple are great helps. Indeed, Gadm.org can provide the needed GIS data, please see Gadm.org on this page. While most current usage are in .png format, .svg is encouraged for it's comparative advantage of scalability.

Innovations

Leading place

Currently, the Arthur Gunn assisted byYug and concepts from ColorBrewer2.org are pushing and developping an online app to receive data, generate an elegant SVG gradiant map, and save its data and settings. The project is done in accessible technologies (HTML, CSS, JS / D3.js) in order to let wikipedia contributors lead the project after Arthur's initial and major push. The project have an huge potential since the decisive GIS data available online may be convert to JSON format and feed this D3.js app with all kinds of backgrounds, areas and items. Most gradient maps on commons aren't categorized as 'gradient map' or any map style. The largest collection of gradient maps there is the list of Maps generated using GunnMap.

Examples

Examples (toolkits)

Basic usages

• 
  Population density
• 
  Internet (2007)
• 
  Internet (2009)
• 
  List_of_terrorist_incidents,_2009
• 
  Foreign_direct_investment (2009)

Using GunnMap

Technologies

GunnMap is an online app coded using accessible technologies, namely HTML, CSS, JS, and D3.js, and under CC-by-sa license. This accessible technologies allow programmers to easily suggest code improvements or new functions.

Usage

Currently for world maps, where countries are associated with polygons and have for id their iso names. The code is actually compatible with any well and strictly coded administrative map where administrative/given areas are represented by a given polygons with a conventional and understandable id name. To generate such well coded map, QGIS and SimpleSVG are very helpful.

Upload to Commons

GunnMap suggests you a code to copy-paste. {GunnMap}

See also

• Gunnmap App — JS/HTML/D3.js map application. You input your data country by country, it generate the gradiant map.
• ColorBrewer2.org for sequencial, diverging, and qualitative color ramps. Web, print, and colorblind friendly.