PTZ fundamentals: zoom, coverage and unattended gaps
A moving view can inspect detail but needs a coverage plan.
Updated
Principle and limits
Pan changes horizontal direction; tilt changes vertical direction; optical zoom changes focal length. Zoom ratio is longest focal length divided by shortest focal length, not a detection distance. Digital enlargement resamples existing pixels. When a single-view PTZ turns toward one incident, other directions may leave its recorded view. A separate panoramic channel, where documented, must be evaluated independently.
Worked example
Consider four presets, each with ten seconds of dwell and two seconds of travel to the next. A complete tour takes 4 × (10+2) = 48 seconds. Each preset receives ten seconds of stable observation and may be absent for the other 38 seconds. A brief event can occur entirely between visits. This arithmetic assumes equal travel times and no operator interruption.
Installation and acceptance
Use fixed coverage for areas that require continuous evidence. Test preset repeatability, focus at long zoom, tracking loss, return position and competing operator commands. Measure target detail at the chosen distance in day and night recordings. Do not promise uninterrupted automatic tracking from the presence of a PTZ motor.