Thread: Design Principles

Question from another thread:

"Those images make the map look like it will be really really small on a 7" screen. Same with video, why is everything so small?"

Because a 7" screen is about 3.5" x 6". In a car it's probably 2x to 3x as far from your eyes as the screen of a desktop computer that the developer created it on. So it's equal to less than 2" x 3" on a computer screen.

That's why I think it's important to eliminate clutter from the screen. When the image goes edge to edge it will 'feel' bigger than it is. Eliminate borders and go all the way to the edge when you can.

And it's a good idea to only put controls on the screen that are really necessary. (If the input isn't through a touchscreen, why reserve ANY screen space for controls?) Controls that will be used while driving are few -- volume mute/unmute and switch function, for example. Depending on what function is shown, change magnification of a map, switch tracks/stations, Play/Pause.

Okay, I'll use my own situation:

My computer screen is 19" from my eyes when I'm typing. My car display is 32" from my eyes when I'm driving, and that's in a MINI so it's closer than many cars. A 7" 16:9 display is 3.43" x 6.10", which is comparable to a 2.04" x 3.62" patch on my computer screen. (To put it another way, a 2" x 3.6" card held 19" from my eyes would block the view of a 7" screen that's 32 inches away.)

The point remains, when designing a front end, remember that when you're in the car, it appears relatively smaller than it did when you were at your computer. Hence the need to give as much of the available screen space as possible to what the driver needs to see.

Another thing that's somewhat misleading to the developer is that he KNOWS what's on the screen, so even when it's very small he gets a mental image of what's on the screen. For those who don't have such an intimate knowledge of what's there, it's harder to find and read the data they need.

I have a 6.5" LCD in my car, physically 640x480, running at 800x600. The smallest font that is readable is Helvetica Bold 14pt - tested on several people independently with random texts displayed. It is slightly better to use white on black than black on white.

The mentioned QCar layout for 800x480 is on the lower end of usability and some modules must go fullscreen in quite a few situations. The small workarea display will be fine for displaying the arrows and driving instructions, but not much for map viewing.

My MINI nav screen is also 6.5", so I feel your pain.

Why not go fullscreen nearly all the time? If you display partial windows, they have to have labels to tell them apart, which further reduces the net display area.

Looking at QCar got me thinking about rotary controls. They're simple, but that means there's few commands. Some ideas for getting more controls from, say, the PowerMate:

1. Use the first action to select a group of actions, for example
   
   • push+twist left to browse commands (or presets) for the current function
   • push+twist right to browse other functions, go to config function, go to shutdown
2. Eliminate duplicate, unnecesary or ambiguous commands to free up actions
   
   • No need for both Play/Pause and Mute/Unmute in a function. In music playback, just have Play/Pause, in radio use the same action for Unmute/Mute.
   • Use the volume control on the radio or amp rather than the PowerMate, if possible

Several of the iPhone's UI features and gestures would be good models for a touchscreen in a car. Its small screen can't hold a lot of information at once, and in a car the driver can't afford to read a lot of text while driving.

Several of the iPhone's UI features and gestures would be good models for a touchscreen in a car. Its small screen can't hold a lot of information at once, and in a car the driver can't afford to read a lot of text while driving.

That would require multitouch, the touch technology developed by apple. As mentioned in the keynote it is pattened and pattened verry well. It would still be cool though.

Originally Posted by bcohen5055

That would require multitouch, the touch technology developed by apple. As mentioned in the keynote it is pattened and pattened verry well. It would still be cool though.

The pinch interface requires multitouch, but flipping over an album to list its contents would not.