Why not use video analytics / VMD region detection for this? You could try built-in capabilities of the existing VMS or camera.
I'd start there to see if that was reliable enough before trying to integrate external sensors.
We have come to rely more on external/indpendent sensors. An example is the motion detection of cameras: Too often tricky and a source of many false (or missed) alarms a PIR OTOH gives, in our experience, more consistent results. We would like to rely on similar.
It is for kiosk. There is a lot of Traffic (motio) within the field of view of the Kiosks cameras. Thus we don'tthink Motion Detection would be the appropriate solution. We need recording to reliably begin only when someone comes close to or is at the Kiosk. The VMS willbe set for 3 secs of Pre-recording before the actual event/alarm of detection by the proximity sensor. A proximity sensor seems to be the Key. When a person or robots :) gets to within 6 feet of the kiosk. Recording starts. The person moves away, recording stops with a post event recording of 3 secs.
As for the $30 budget it seems indeed to be low. Our research shows $75~$120 to be the range for a microwave-type proximity detector. We still need your input and experience with such a solution.
For arguments sake why couldn't you use something like this?
PIR with shields (or you can use tape, but the shields look cleaner) over the kiosk to narrow its viewing angle. If you can set it up overhead at approximately 8ft, I would use a REX as those come with small plastic shields. I guess you could use a beam detector if its mounting fits into the application and there is a need for that precision.
What is the purpose of the camera recording? Is it to watch for theft/vandalism or are they looking for a way to count how many times a day people interact with the kiosk?
You might consider a pressure mat alarm sensor. We have used these to trip door locks on the secure side of the door in a high traffic area when we didn't want background traffic to constantly trip motion sensors. Just a quick google search, but here's an example: http://www.amazon.com/EasyAlarms-Pressure-Burglar-Security-System/dp/B001QC98RC
Silva Consultants | 06/18/15 04:33am
Alarm Controls recently introduced a request-to-exit motion detector called the SREX-100 that is supposed to have tightly controlled coverage pattern and adjustable range. I haven't personally tested one, but it sounds like it might work in your application.
Von Duprin used to sell a request-to-exit detector that used a Polaroid Range Finder as its detection device. You could precisely set the detection range down to 1/4" increments and it wouldn't detect anything closer or farther away - a remarkably accurate device. Unfortunately the device emitted a constant "ticking" sound in the ultrasonic range that some people could hear and find annoying. (I'm sure that dogs loved it too...). It's no longer sold and I have yet to find a motion detector whose detection pattern can be so well controlled.
Google Long range RFID Tags and receivers
You will easily get up to ~ 100 feet range
I am repeating there is a substantial of people traffic around the Kiosk. This will fool Motion Detection activated recordings.
So then what's with the whole 'start recording when 6-8 feet away' requirement?
Does the person have to interact (touch) the kiosk to use it?
If so why not just use a capacitive sensor on the screen bezel? Or a short range robotic IR sensor? With 30 second pre/post record?
Are you recording the interaction for business intellgence or for asset protection?
I'd be glad to suggest actual components if you think it's worth exploring.
If you have not chosen or installed any system yet, you could use a Mobotox camera and use onboard event logic using VM windows. Meaning VM1 needs to trip followed up by VM2 and this would allow for directional based event recording. This is proven to work and very reliable in kiosks, Not to mention you get the entire solution built into a single device. In addition Mobotix is slated to release our own Proximity detector should you wish to keep it to a single provider. Just a thought.