Guide · Nx Witness
Intrusion detection in Nx Witness: setting it up with AI.
To detect an intrusion in Nx Witness, install the IA-N Analyse plugin inside the Nx server, tick IA-N on the camera, then draw a zone in “Alarm rules › Intrusion” and choose the objects concerned: people, vehicles or animals. Each intrusion becomes an Nx event “IA-N: Intrusion”, which you link, in the Nx event rules, to a notification, a bookmark or a recording. Alarm rules are part of the Advanced rules option, included in the 30-day free trial.
Updated on 21 October 2026
Before you start
What the Nx server needs.
- The IA-N Analyse plugin installed inside the Nx server, with a licence or the 30-day free trial.
- The Advanced rules option for the camera (the trial includes it on 4 cameras).
- The camera recording in Nx: Nx only passes frames to the plugin when the camera is recorded or viewed.
- The objects to monitor ticked on the camera's main “IA-N Analyse” page: People, Vehicles, Animals.
Step by step
Four steps in the Nx client.
- 01 / Enable
IA-N on the camera
Camera Settings › Integrations › “IA-N Analyse”: tick IA-N, then Apply. The camera takes a licence place.
- 02 / Draw
The intrusion zone
“Alarm rules › Intrusion” page, “Intrusion zone 1 (new)” box: type the name of the zone, which will appear in the alarm, then place 3 to 12 points on the image, over the forbidden area only.
- 03 / Set
Objects and delays
“Objects”: those that must not be there. “Minimum presence before the alarm (s)” and “Minimum delay between two alarms (s)”: 0 gives the recommended values. Then Apply.
- 04 / Link
To an action in Nx
Nx event rules: new rule, Analytics Event “IA-N: Intrusion” on the camera, then the desired action (notification, bookmark, recording, e-mail…), with a schedule if needed. Do a test pass.
Recommended settings
The values that avoid false alarms.
| Objects | People for a closed site, Animals for a garden, Vehicles for a pedestrian path. |
| Minimum presence before the alarm | 0 = immediate alarm; 2 to 5 s if passers-by brush past the zone. |
| Minimum delay between two alarms | 0 = 30 s for the zone; an object that stays in the zone does not trigger again. |
| Ignore stationary objects | Ticked by default: no alarm for a stationary vehicle or animal; a person who arrives is reported once. |
| Point tested | The centre of the object's box. |
| Number of zones | Up to 8 zones per rule and per camera, with 3 to 12 points each. |
Changing a camera's settings restarts its analysis (a gap of 1 to 3 seconds in its recording has been observed): do it at commissioning.
The other alarms
One page per rule, one Nx event per alarm.
| Rule | When the alarm is sent | Nx event |
|---|---|---|
| Intrusion | Object in the zone for the chosen time | IA-N: Intrusion |
| Zone entry / exit | Object entering or leaving the zone | IA-N: Zone entry; IA-N: Zone exit |
| Line crossing | Object crossing the line in the monitored direction | IA-N: Line crossing |
| Tailgating | Several crossings in the same direction within a short time | IA-N: Tailgating |
| Loitering | Continuous presence beyond the set time (60 s recommended) | IA-N: Loitering |
| Dwell time | Object that stayed beyond the maximum duration | IA-N: Dwell time exceeded (parking) |
| Crowd | At least N chosen objects in the zone for the set time | IA-N: Crowd |
Each rule is drawn on its own page, under “Alarm rules”, in the same way as the intrusion.
Common mistakes
If the alarm is not sent, or is sent too often.
- Zone that spills over onto the street or the sidewalk: every passer-by gives an alarm. Draw only the forbidden area.
- Object not ticked on the camera's main page: nothing happens.
- Delay between two alarms too short (1 s): one alarm per second in Nx. Keep 30 s.
- The centre of the box is what counts: a person with only their feet touching the zone is not counted as inside.
- No alarm for a parked car or a person waiting without moving: this is intended, the “Ignore stationary objects” box is ticked.
- Alarm visible in the event log but no notification: check the Nx event rule.
Privacy: mask neighbours' windows and the public road with the camera's “Excluded zones”; nothing is analysed there.
Frequently asked questions
Intrusion in Nx Witness
Another question? Our sales team will answer.
Do you need AI cameras to detect an intrusion in Nx Witness?
No. The IA-N Analyse plugin runs the analysis inside the Nx server, from the frames of the cameras already installed.
Can the plugin tell a person from an animal?
Yes. It detects people, vehicles and animals; in each zone, you choose the objects that trigger the alarm.
How do I limit intrusion alarms to the night?
With a schedule in the Nx event rule, for example nights and weekends. For alarm monitoring, the plugin also has its own transmission schedule.
How many intrusion zones per camera?
Up to 8 zones per rule and per camera, each with 3 to 12 points. The “Line crossing” page also accepts up to 6 lines.
Can intrusion alarms be found in the archive?
Yes. Alarms are Nx events, visible in the event log, and the objects' boxes are also drawn during archive playback when the “Objects” tab is open.
Also worth reading
To find out more.
Nx Witness is a trademark of Network Optix, Inc.; DW Spectrum, of Digital Watchdog.
Test intrusion detection on your Nx server?
The 30-day free trial includes alarm rules on 4 cameras.