To be honest, I am not sure why they were trying to setup IVS for Vehicles anyway. Then as you pointed out having it appear isn't a good idea when the area to be protected is covered in vehicles lol.. Now it might be that the camera detects the vehicle in appear after maybe an Alarm has gone off on the car? Because as pointed out it might detect once then seeing it knows it is there shouldn't detect it again until say the blinkers or lights turn on. Then it would notice that there was something different and appear could trigger again. Also would more then likely trigger on a Change from B/W to Color because all the cars would have changed the last known detected state on the appear..
So I know it isn't me, But if it was me, I would have IVS setup with Human detection, I would setup the cameras with a good area of detection of a person coming to the line for crossing with the Ai rule setup as cross. Then it could see the person know they were outside the line and clearly crossed it so event triggers.. If an Intrusion box is to wide to the detection scene the action of someone moving into the box might be missed, then everything they do isn't triggered and recorded. However having the ability to clearly see the human outside of that box it will false less then if setup with appear.. But if there is no clear line to cross only option is that could work is appear and that detection area they could already be 2 or 3 cars in before that camera where placed would detect appear for sure at night.. Wrong camera for the scene..
How I would setup, Intrusion or Tripwire acting as a box with clear outside area of view and in this case might do as I see so many others do zigzag the intrusion inside. But not needed if there is a clear line of sight from outside of the box.. Setup for Humans and for sure where that open area on left, have a single line that runs from top area where that building is down to end of site with human and vehicle so anything that crosses that clear line would trigger an event.. Then because I am guessing Car alarms going off can do so for many different reasons. I would also have motion enabled and in this case using after the fact filtering with playback to see what might have been missed by Ai IVS.. Only things that should be missed is because the intrusion or tripwire wasn't setup correctly to start with and a human made it past the line without triggering it again because in the current setup there is no clear outside area for the camera to know it has crossed the line until it is more then likely to late and never trigger the event to start with..
I don't know if they might have had Scene change enabled if that was an option for their camera or NVR setup. Don't have picture of the event or video of what was going on before or after the triggered event so can only guess and try to offer some ideas of what I might do to help correct so others that might read having same kind of issues might understand how someone could setup the scene for better detection.
I am human and I make mistakes.. It is what I do with those mistakes that can make me a better person..
