Stairs, crossings and other safety-critical zones need a rule that clears or fades overlays

What it is

A stairhead, a zebra crossing, a platform edge does not negotiate with overlays. The ground and the cross traffic at these places must be seen. Geofenced overlay clearance uses a place rule to force layers off, or down to almost no contrast — not waiting for the task step to end, not waiting for the user to remember to close.

Motion-triggered thinning watches whether the person is walking. This watches which class of place they have entered. Standing at a crossing still clears.

Why it happens

Stairs and crossings turn failure into a fall or a hit. Tread edges, people from the other side, signal lamps are structures that have to be confirmed with the eyes; “the layer is quite faint” is not a bet you get to make. Attention at these places is already near full; any panel still in the centre is competing with the tread. The rule has to be place-triggered and not exempted by the current task: even if the assembly drawing is unfinished, the stairs get the view first.

Translucency is not equivalent to clear. Translucency still occupies features and still pulls gaze. The safety-zone default should unload every layer that can unload, leaving one heading cue that does not sit on the tread; if unload is impossible, drop to wireframe and keep out of the lower view. The fence can come from a pre-marked map, from repeated step structure in depth, or from localization at a crossing. Miss one staircase and the rule is none.

Studying it

Walk a task on real or built stairs and a pedestrian crossing, comparing no rule, a post-arrival “consider closing,” forced clear, and forced translucency. Primary scores: missed treads, stops, whether and when the signal lamp is looked at, and whether the layer has already yielded before the first step is taken.

Place factors: stairs, kerb, zebra, platform. Rules: prompt vs force, clear vs translucent, lower-view protection or not. Safety: missed treads, stumbles, tendency to walk into the carriageway; task: whether a clear makes the task unrecoverable after.

A “stair” poster on the flat cannot measure tread confirmation. There has to be a real level change or a real kerb.

Where it stops holding

Indoor single thresholds and low exhibit steps, cleared every time, will shatter the experience; grade places that can fall or intersect traffic, rather than every change in height. A staircase absent from the map will miss the fence; visual detection of treads or the walking tier has to catch it. A theatre of surgery’s “critical zone” is the sterile field, not stairs; the fence’s meaning has to be swappable, not hardcoded as stairs alone. Forced clear interrupts work; on leaving the zone, one-tap restore must exist, or people will kill the whole rule. Users of tactile paving and ramps have a different “stair” model; fences should use an accessibility map, not only marked steps.

Applying it

• Pre-fence stairs, crossings, platforms, docks: one step before entry, force-unload solid layers and lower-view content. Only a thin heading line that does not sit on the tread may remain.
• Translucency is not a compliant means at these places. To keep information, switch to wireframe and keep it out of the lower view where treads live.
• When the fence misses, the walking tier and lower-view protection are the second line. Both off is the violation.
• How to check: walk a real stair with a panel still being read. Before the first tread, the panel should be out of the lower view and the centre. Reading a paragraph onto the first tread, or a translucent panel still covering the tread edge, means the place rule is not yet forced.

Related

• Same group：N5.13.1 An overlay hiding a dynamic hazard in the real environment is the highest-grade risk · N5.13.2 While moving, overlay density should drop to leave attention for the environment · N5.13.3 On a performance crash or see-through failure, fallback must prioritize environment visibility · N5.13.5 Long-term reliance on overlay cues weakens active scanning of the real environment
• Nearby：N5.07 Overlay Density · N5.12 Overlay Density in Real-world Context
• Search terms：geofenced overlay clearance · stair safety AR · crossing HUD