tilemill_workshop1.md

Tilemill and OSM

## Data sources

• http://download.geofabrik.de/ (countries, continents...)
• http://openstreetmapdata.com/data (land, water, coastline, preprocessed in shapefiles)
• https://www.mapbox.com/tilemill/docs/manual/mapbox-geodata/ (main boundaries, populated places...)
• relief data: http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp
• some cities: http://metro.teczno.com/
• targeted osm data: http://overpass-turbo.eu
• in shp http://www.openstreetmap.re/osm2gis/
• in shp (and others): http://extract.bbbike.org/
• relief data: http://www.eea.europa.eu/data-and-maps/data/eu-dem

## Accepted formats:

Details: https://www.mapbox.com/tilemill/docs/manual/adding-layers/

• psql
• shp
• csv
• geotiff
• geojson
• kml
• sqlite

Prepare data

• online converter: http://geoconverter.hsr.ch/
• simplifying vectors: http://mapshaper.org/
• know about OSM format http://wiki.openstreetmap.org/wiki/Map_Features

## Style data

### Anatomy of MSS

#thisisanid, it's unique (only one layer)

.thisiaclass, it can be shared between layers

#myid[field='value'] this is selector

#myid[field='value'][anotherfield='value'] means AND

#myid[field='value'], #myid[anotherfield='value'] means OR

line-color: #123 this is a symbolizer (or rule)

::attachment allow to have more than one selector for the same feature (otherwise, the last to come will win); very often used for casing or glow effects.

outline/line-color: blue is a named instance, like attachment, it allows to have multiple styles of the same type applied on a same feature

'@secondary_line: #9FA9A8;` this is a variable

Selectors can be nested, and rules are inherited.

Painter algorythm: first rule to come, first rule to be drawn (notable exception: labels!), others will be drawn of top (unless you play with *-allow-overlap). Roughly: layer order, then stylesheet order, then order of the selector, then order of the symbolizer, then order in the data source More about this: https://www.mapbox.com/tilemill/docs/guides/symbol-drawing-order/

Labels and icon algorithm:

doing the job

• main elements: landuse, roads, buildings
• take zoom into account
• add icons
• add labels
• add custom fonts
• use variables
• understand the drawing order
• understand the text priority drawing order
• use functions
• replace strings in names

Export data

• upload to MapBox for quick and dirty prototyping
• export to png / jpeg / tiff
• export to svg
• export to MBTiles
• share your styles (sources!)

## Advanced:

• relief data
• psql
• use version control

Resources

• official manual: https://www.mapbox.com/tilemill/docs/manual/carto/
• official guides: https://www.mapbox.com/tilemill/docs/guides/add-shapefile/
• official reference: https://www.mapbox.com/carto/api/2.3.0/
• http://skorasaurus.github.io/carto-manual/