Turn right please, why navigation screens should obey the rules of perception

’Turn right please’
Why navigation screens should obey the rules of perception

Article
Published in: Tec September 2010
Leonard Verhoef
Contact.

Centuries ago the only dynamic screen was a stage. The width of a stage is greater than it’s height. The successor of the stage is the screen a movie is projected onto. It has a landscape orientation. That makes sense.

The same applies to the next technological successor, the TV screen. TV screen technology was used for computer screens. Computer screens have a landscape orientation as well. Does that make sense for car navigation screens?

Which route?

Before departure the car driver selects a route from those that lead to his destination. There are more parameters of a route than there are routes (see Figure at the right). For selecting a route, a landscape orientation makes sense.

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Figure 1, a wide short list, landscape is the best choice

When to turn?

In the car the task of the driver changes from comparing a broad range of characteristics from a few trip options, to carrying out a long list of short instructions. For such a list, a portrait orientation makes sense (See Figure at the right). The eyes should look inside as short as possible and the visual presentation therefore should be perfect.

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Figure 2, a narrow long list, portait is the best choice

‘Fuel needed’ mode
The car driver can see that there is a petrol station in 46 km. That is across border (cheaper petrol) and has a toilet and a playground.

Common practice in car navigation is a landscape orientation as in the figure at the right.. This does not make sense.

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Figure 3, a realistic landscape planning screen

The orientation is landscape, of course, The rules of perspective determine the size of the information and not the rules of perception. Information at a great distance is not readable. The car driver cannot see close to and beyond the horizon because the scale of distance is according to rules of perspective.

Source: Tom Tom, 2010

When to stop?

Navigation includes knowing when to turn. It also includes planning. A car driver looks ahead to increase alertness when he approaches his exit. He wants a petrol station just before he runs out of petrol and a restaurant at dinner time. See Figure 2, above. Will he stop at the first or the second one? See Figure at the right. He plans to change driver and to stop for a toilet preferably at the same stop.

Figure 4, this sign helps drivers not making a serious planning error that might appear behind the horizon.

The conclusion is clear. The screen should not show realistic clouds and petrol stations at a size consistent with the laws of perspective which means they are becoming more invisible at the horizon and hide what is behind the horizon (See Figure 3 above). The screen should show the distance to petrol stations and restaurants consistent with the laws of readability, especially for objects that are close to or even behind the horizon.
A non-realistic portrait orientation allows a much better and more readable presentation of targets that are invisible. The abstract presentation in the Figure at the right therefore makes sense.

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Figure 5, a non-realistic portrait planning presentation

A high speed train driver route planning interface.
The orientation is portrait. It is not the rules of perspective that determine the size of the information but the rules of perception. Information at a great distance is readable as well. The train driver can see far beyond the horizon because the scale of distance is not realistic or proportional to the perceived distance outside the train. The driver clearly can see what is ahead: ‘give horn’, ‘level crossing’, ‘tunnel’ and a ‘red signal at 4000 meter’. The scale is proportional to the task: close by, immediate action has more pixels per distance. Great distance, actions in several minutes has less pixels per distance.

Source: ETCS (European Train Control system, driver mmi.