Output level is not an accuracy slider
Many RTLS proposals treat presence, 1D, and 2D/3D as if they were simply “accuracy settings.”
In reality, each output level represents a different system architecture with different installation,
maintenance, and risk profiles.
1) Presence: when “inside or outside” is the real requirement
Presence-based RTLS answers a simple question: Is the person or asset inside this zone?
This is enough for many industrial problems—restricted area control, mustering,
and basic compliance reporting.
1.1 What presence does well
- Clear zone entry/exit events
- Low infrastructure density
- High robustness when zones are well defined
1.2 Where presence breaks down
- When distance to a hazard matters (e.g., anti-collision)
- When zones are very small or tightly adjacent
- When workflows depend on relative positioning between entities
If your acceptance criteria only mention “enter/leave” and dwell time,
presence is often the most cost-effective and reliable output level.
2) 1D positioning: the overlooked middle ground
1D positioning tracks movement along a defined path or axis—tunnels, corridors,
long aisles, or conveyor-aligned workflows.
It answers “where along the line” rather than “where in space.”
2.1 Why 1D is often the correct answer
- Many industrial movements are constrained to linear paths
- Anchor placement is simpler and more predictable
- Edge and corner errors are easier to control
2.2 Common mistake: forcing 2D into a 1D world
In tunnels and aisles, teams often request 2D positioning out of habit.
This increases anchor count and tuning effort without improving decisions.
A well-defined 1D system usually delivers more stable and interpretable data.
3) 2D/3D positioning: powerful, but demanding
2D and 3D RTLS provide full spatial relationships between people, vehicles,
and assets. This level is essential for anti-collision logic, coordinated movements,
and dense interaction zones.
3.1 What 2D/3D really requires
- At least three anchors simultaneously visible in the target area
- Good geometry across the entire working zone, not just the center
- Stable time synchronization and consistent calibration
3.2 Why edges dominate system performance
Most complaints about “unstable RTLS” originate at zone boundaries:
corners, rack ends, doorways, and mixed indoor/outdoor areas.
These are exactly where anchor geometry degrades and small timing errors
become large position errors.
4) Choosing the output level by use case
| Use case | Recommended output level | Reason |
|---|---|---|
| Restricted area access | Presence | Clear entry/exit events are sufficient |
| Tunnel worker tracking | 1D | Movement constrained to a linear path |
| Forklift–person safety | 2D | Relative distance and direction matter |
| Yard dispatch & coordination | 2D / Hybrid | Spatial relationships across open areas |
5) The hidden cost curve of output levels
As output level increases, three costs rise non-linearly:
- Infrastructure density: more anchors, more planning, more installation risk
- Commissioning effort: calibration, worst-zone testing, and iteration
- Operational sensitivity: small failures cause visible system behavior
This is why “over-asking” for 2D/3D often produces systems that are more expensive
and less trusted by operators.
6) How to specify output level in procurement
Avoid vague language like “high precision everywhere.”
Instead, specify:
- Which events must trigger reliably
- Where they must work (worst zones)
- Acceptable latency and failure behavior
When output level is specified this way, vendors can design and test against the same target,
and acceptance becomes objective rather than subjective.
TL;DR
RTLS projects fail most often because the required output level is over-specified.
Presence, 1D, and 2D/3D positioning are not “accuracy tiers” but different system designs with very different anchor density, installation complexity, and failure modes.
Define the event you must trigger and the worst-case zone where it must work.
If you ask for 2D/3D when presence or 1D would have solved the operational problem, you will pay more, deploy slower, and argue longer—without improving outcomes.
Key takeaways
- Output level is a system design choice, not just a software setting.
- Presence solves many compliance and safety problems at a fraction of the cost of 2D.
- 1D positioning is the natural fit for tunnels, aisles, and linear workflows.
- 2D/3D should be reserved for workflows that truly require spatial relationships.
- The correct question is “Where must this work reliably?”—not “How accurate can it be?”
Quick facts
FAQ
Can presence-based RTLS be used for safety applications?
Yes, when safety requirements are zone-based (e.g., restricted area control). For distance-based safety (anti-collision), presence alone is insufficient.
Why does 2D RTLS cost increase so fast compared to presence?
Because anchor density, geometry constraints, and commissioning effort scale quickly to guarantee coverage in worst zones.
Is 1D positioning less accurate than 2D?
It is different, not worse. In linear environments, 1D positioning can be more stable and meaningful than forcing a 2D solution.
Can a system mix output levels?
Yes. Many deployments use presence in peripheral zones and 2D only in critical interaction areas.
How should acceptance tests differ by output level?
Presence tests focus on entry/exit reliability, 1D tests on progression consistency, and 2D tests on worst-zone accuracy and latency.