roomthily

Turn by turn

A recent conversation with one of the leading makers of portable satellite-navigation devices left your correspondent similarly confused. The next generation of satnav equipment—whether portable or built into vehicles—will have their digital maps overlaid with photogrammetry information to show three-dimensional images of the streets, buildings and terrain ahead, all rendered with the appropriate texture. The result will be a virtual replica of the scene the motorist sees through the vehicle’s windscreen.

Two questions spring to mind. First, why bother? Surely, it would be easier—and possibly even more realistic, if that is the objective—simply to attach a video camera to the front of the car and then digitally overlay the moving image shown on a dashboard display with the necessary navigation instructions. After all, that is the kind of “augmented reality” application that is being adopted on mobile phones. Second, do drivers struggling to find their way while coping with the traffic really want all that graphical information? Much of the research into information overload and driver distraction suggests that less is invariably better.

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Motorists are not all that different. With a satnav, where the visual information has to be grasped in no more than a second or two, the object should be not to add graphically to the complexity, but to reduce it to the bare essentials. The optic nerve and brain then have an easier task coping with the additional load while concentrating on the more demanding task—driving the vehicle.

To a certain extent, all maps rely on some form of abstraction. Sometimes that means omitting details; at other times it involves simplifying or distorting salient features to improve legibility. One of the most ingenious examples of abstraction is the map of the London Underground. Designed originally by Harry Beck in 1933, the map pioneered the use of straight lines in place of actual winding routes and abandoned scale for simplicity. For three-quarters of a century, the map has remained a model of all that is easy to grasp at a glance.

A more recent example of ingenious abstraction is the LineDrive methodology for route mapping developed at Stanford University in California. The technology is based on the cognitive psychology of how route maps are actually used, as well as the rough but highly effective directions people draw for one another on the backs of paper napkins. Surveys reveal that LineDrive maps—which, uncluttered by extraneous detail, show just a single trace from the origin to the destination, annotated only by helpful navigational aids such as route numbers and names of important cross streets—are preferred every time over standard computer-generated route maps.

example of a LineDrive map abstraction (via Stanford)

Like Beck’s map of the London Underground, LineDrive uses different scales for different sections of the route, depending on their importance to the driver’s understanding. Landmarks are used sparingly and all unnecessary features are removed. As a result, they tend to be exceptionally easy to read and reduce the perceptual load on the driver.

via The Economist