I began my GIS career using ArcIMS. These were ancient times… in order to specify “this line should be red“, one had to know ArcIMS’s proprietary XML. It was ghastly then, and it’s ghastly now. Using Google Earth? The cartography is represented by KML. Using TileMill? Your CartoCSS is translated to XML behind the scenes. Using ESRI? At best, your symbology is stored as JSON. QGIS? QML. MapServer? Arcane plain text. GeoServer? SLD.
This is not meant to be a comparison of data formats, but of the breadth of different cartographic styling languages.
A raster in any of these programs will look the same. With rasters, the software doesn’t matter — this is why OGC WMS was so successful. Things did fall apart for WMS around the edges – OGC Styled Layer Descriptions (SLDs) were seldom used, and that style specification never really gained traction. Seldom did a client really need to supply alternative cartography to a WMS. The idea of a WFS server passing an SLD to a client as rendering instructions would be great, but its something I’ve never seen real world implementations of.
Hence vector styling has remained the wild west. ESRI recently said they’d use a “format based on existing community specifications” for vector tile maps. Presumably, that means CartoCSS or some variant. The question looms “can I use my ArcMap symbology for ESRI vector tiles”? [It’s worth plugging Arc2Earth‘s TileMill Connect feature here.] The opposite is also true. It’s become simple to export OpenStreetMap data into ESRI-friendly formats. Nevertheless, it will look terrible out of the box, you’ll have a devil of a time finding a cartographer to work on it, and its impossible for ESRI’s rendering engine to match OSM’s / Mapnik‘s rendering engine.
We are blessed in GIS, until the words cartographer and style trigger the cringe-worthy vector rasterization engine. Nevertheless, this world is upon us. Cloud resources such as OpenStreetMap and Twitter are defining the new worlds of cartography. MapD’s Twitter Demo exemplifies how big data requires new types of rasterization engines. Recently MapBox has shifted from a server-side Mapnik rendering engine to a client-side MapBox GL; no doubt vastly reducing their storage and processing overhead.
Those of us building new GIS applications – even the mundane – should start by worrying about the cartography. Data set support, application capabilities, application performance, cartographic costs, data storage sizes, and interoperability with other programs are just a few of the critical reasons why having good style is important.
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