Begin with the question each signal answers
GPS describes a device’s reported location. A geofence compares that location with a configured boundary. Liveness examines aspects of the capture interaction. Face verification compares a claimed identity with an enrolled reference; identification searches a set of references for a candidate identity.
These signals are not interchangeable. A live person near a site is not necessarily the enrolled worker, and a successful face match does not establish where work occurred or how many hours should be paid.
Scroll the table sideways to read all columns.
| Method | Useful question | Material limitation |
|---|---|---|
| GPS stamp | Where did the device report being? | Accuracy and fabricated inputs |
| Geofence validation | Did reported coordinates meet the boundary? | Does not authenticate the coordinates |
| Liveness challenge | Did the capture satisfy the implemented live-response check? | Not identity proof or guaranteed spoof resistance |
| 1:1 matching | Is the candidate similar to this enrolled worker? | False accepts/rejects, capture quality and client trust |
| 1:N identification | Which eligible reference is the best candidate? | More candidates, ambiguity and distinct processing purpose |
Compare the operational costs too
Location requirements can reject genuine workers with poor fixes. Biometric matching adds enrollment, worker information, privacy assessment and a fallback for failed or declined matching. A shared device needs power, network and capacity at arrival time. Choose a proportionate workflow after testing those conditions.
Neither method alone calculates valid payroll. You still need schedules, missing-punch review, correction reasons and an export reconciliation process.
Where Attendify fits
The personal-device flow combines liveness selfie and event location. Optional 1:1 matching and site-kiosk 1:N identification are controlled features. Candidate inference runs on the device and the server compares against reference data; modified-client inputs remain a limitation.
Accepted attendance selfies are stored privately. Using a numeric matching template does not remove all photography or biometric privacy considerations. See NIST’s biometric authentication discussion for technical distinctions, and seek jurisdiction-specific guidance for the proposed workforce processing.
Make a pilot decision
Write down the evidence you need, the consequence of an incorrect result and the usable fallback. Test actual devices and representative conditions, then compare the cost of exceptions as well as successful punches. Avoid selecting a method on an unsupported accuracy percentage.