Creating thematics with Mapnik

[Maxime Demers]

Hi,

I would like to know if its possible (or if its planned to be) to create thematics based on field values. Like in every GIS you can create classes and give perticular style to it, like color gradient.

Thank you

[Edward Mac Gillavry]

Hi Maxime,

Getting to know Mapnik, you will often find that most applications of the map rendering software are applied to topographic or reference maps only. Indeed, Mapnik is used to render the default visualisation for the OpenStreetMap tiles, but also for Mapquest Open, Mapbox Streets and Mappy.

However, you can most certainly apply Mapnik for thematic mapping as well. The core of this functionality is the <Filter> tag, that you use to select the column from your data that you would like to portray. Check out https://github.com/mapnik/mapnik/wiki/World-population-tutorial for an example of this.

Both TileMill by Mapbox (http://www.mapbox.com/tilemill/) and CartoDB by Vizzuality (http://cartodb.com/) are GUI-based applications that use Mapnik 'under the hood' and are very powerful tools to create thematic maps without having to go into the Mapnik XML as they provide an easy to use CartoCSS language to style the maps. The results of your CartoCSS editing is immediately visible in the map pane of the application as well, so you an explore the data interactively and can quickly modify the look and feel of the map so prepare the final map. Here is a tutorial to create a proportinal symbol map using TileMill (http://www.mapbox.com/tilemill/docs/guides/advanced-map-design/) or check out how to create a choropleth map using CartoDB (http://developers.cartodb.com/tutorials/electoral_map.html).

Data processing, classification of your data set, map type and colour range selection are really left up to you to decide, but then Mapnik can beautifully render a thematic map either as a stand-alone renderer or wrapped in a TileMill or CartoDB instance.

Regards,

Edward

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Date: Mon, 29 Jul 2013 09:31:27 -0700
From: burt...@gmail.com
To: map...@googlegroups.com
Subject: [mapnik] Creating thematics with Mapnik

Hi,

I would like to know if its possible (or if its planned to be) to create thematics based on field values. Like in every GIS you can create classes and give perticular style to it, like color gradient.

Thank you

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