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Walk & Ride

High precision for large scales. Because the data used by United Maps shows the outline of every building, it needs to be stored and rendered at greater precision than is normally needed. CartoType's CTM1 data format can store points to a resolution of less than 2 centimetres, providing more than enough accuracy. The data sets remain compact enough for an entire city such as Hamburg, plus the Walk & Ride application, to be stored in less than 10Mb, which is the limit for applications downloaded from the AppStore.

Multi-modal routing. One of the most attractive and useful features of Walk & Ride is the routing. Just select two places, and the application quickly calculates three routes: a walkable route for pedestrians, a drivable route for private cars, and a multi-modal route for users of public transport. CartoType's routing system, which is provided as an integral part of the CartoType package, uses the connectivity of the map data, in conjunction with parameters set by the application, to find the best route, defined as the route with the least cost according to suitable weightings such as expected speed along certain types of road.

Style sheet flexibility. United Maps needed to draw maps at a wide variety of scales. At the most zoomed-out scale the whole city fits on to the iPhone display. When you zoom right in you are looking at part of a street and the outlines of buildings alongside it. CartoType's flexible XML style sheet format makes this relatively easy. Layers are enabled and disabled at different scales, and within layers detailed adjustments are made. Within a range of scales drawn using the same style, features scale smoothly. The most convenient way to specify the size of a feature is in map metres, but you can also use pixels, or real-world units like centimetres and inches. Every dimension can have an optional maximum and minimum size, making it very easy to designate a road, for example, as being drawn at an effective width of 25 map metres (that is, as if it was 25 metres wide in the real world) but with a minimum width of 2 pixels.

Scalable icons. Over forty different icons help users distinguish different points of interest like railway stations, car parks, pharmacies, post offices and historic monuments. They are defined in the SVG (scalable vector graphics) language and embedded in the style sheet. They are always rendered correctly at any size, and can use attractive graphics features like semi-transparency and color gradients.

Typography. CartoType can render any TrueType or PostScript Type 1 font, so there was no difficulty when United Maps decided to use their own choice of font instead of the ones supplied as part of the CartoType package. Unicode is used throughout CartoType, eliminating most encoding problems. Naturally, typographic units can be used in style sheets when specifying font sizes.