Designing touch interfaces for gloves and glare
Interface conventions come from phones held at arm's length indoors. A wall-mounted screen in a warehouse breaks nearly all of them.
Every touch interface guideline you have absorbed assumes a phone: held close, indoors, operated with a bare fingertip by someone giving it full attention. Change any of those and the guidance stops applying.
Targets need to be much bigger
The 44-point minimum is for a fingertip at close range. A gloved hand on a wall-mounted screen, at arm's length, by someone in a hurry needs far more - we start around 80 to 100 points for primary actions and go up in industrial settings.
Spacing matters as much as size. An accidental tap on the wrong control is worse than a missed tap, because the user may not notice.
Contrast for actual conditions
Screens live under warehouse lighting, next to windows, in direct afternoon sun. Subtle grey-on-white looks refined in the studio and disappears entirely on site.
- Aim well past the WCAG minimum, not exactly at it
- Avoid thin type weights at any size
- Assume a matte, possibly scratched surface diffusing everything
- Go and look at the device in the actual room before signing off
No hover, no precision, no patience
There is no hover state, no right-click, no keyboard. Gestures are undiscoverable to a first-time user who will never get a second explanation.
Everything important is a visible, labelled button. Icon-only controls fail constantly in unattended settings - the icon that is obvious to the designer is a mystery to a member of the public.
Design the idle state
Most of a kiosk's life is spent with nobody in front of it. The attract screen does the real work of telling passers-by what the thing is for, and it needs to reset reliably from any state a previous user left behind - including halfway through a form with their data on screen.
That timeout is a privacy control as much as an interface one.