IR Cameras for monitoring auditoriums

[Daniel Fredrickson]

Hi All,

I was wondering if anyone has had any experience with installing IR cameras in auditoriums, or if they have any suggestions for brands/etc? Maybe do's and dont's?

We are approaching a remodel and thinking about installing high-res IR PoE cameras in the front of the auditoriums that face back at the seating areas. We are however concerned of the cameras' IR interference with our ALD/CC systems. We use USL IRC-28C transmitters located at the rear of our auditoriums near the port-hole windows. IR light (at presumably slightly different wavelengths) would be flooding out into the seating area from both the camera and the IRC-28C. Since our assistive-listening devices and caption readers receive their signal via line-of-sight IR, I assume this could be an issue?

Does anyone have any experience with something similar, or recommendations? I'm hoping to avoid a trial/error situation.

Thanks!

[Ryan Gallagher]

I expect there is some industry experience with this. Most major playhouses have IR cameras and emitters (granted they usually point at the stage)... would probably need to hear from a mixed used theatrical/cinema house that has tried to do what you are doing with that particular set of competing devices.

[Marcel Birgelen]

I've seen large LED walls interfere with IR-based hearing equipment, although the amount of IR coming off of the LED wall was minimal. My theory is that the LED wall emitted so much light, that it blinded the IR sensors, combined with the fact that a LED wall reflects far less light than your standard cinema screen. We moved the transmitter in front of the screen, but that only marginally improved the situation.

Interference in many cases is hard to predict and often comes a bit unexpected. Interesting example: Last year, on the Belgian Tomorrowland Festival, the main stage burned down two days before the start of the festival. As a replacement, they built a replacement stage with a massive LED wall within two days. Since there was essentially no time for anything, the thing was almost completely unshielded. The EM interference this thing caused played havoc with the local 5G and WiFi networks...

So, although I don't really expect any big issues with standard IR cams, the fact is that it's hard to predict upfront. Maybe you can look up on what frequency range your ALD system is running and compare that to what IR frequencies the cameras are emitting, if you can get those specs. If those are close together or overlap, you might still expect problems.

[Ryan Gallagher]

The IR camera is less the problem... it will be the IR emitters you need to install to get the kind of IR light level wanted to utilize the IR features of the camera.

Many of those camera have IR and normal modes, I'd consider one of those models... worse case you've got a audience facing camera... it just can't perform it's IR function. But film throws lots of light into the house... you'd potentially only need the IR emitters pre-show and post-show... perhaps when the ADA devices are not in use?

[Harold Hallikainen]

The IRC emits at 870 nm. I suspect that an IR camera pointed anywhere near it will be severely overloaded, but it would be fun to try out with a borrowed camera. Moving the IRC to the front of the auditorium, where the camera is, would eliminate this problem. The IRC could then serve double duty of providing assistive listening/audio description/closed captions as well as providing IR illumination for the camera.

[Marcel Birgelen]

The IR camera is less the problem... it will be the IR emitters you need to install to get the kind of IR light level wanted to utilize the IR features of the camera.

Many of those camera have IR and normal modes, I'd consider one of those models... worse case you've got a audience facing camera... it just can't perform it's IR function. But film throws lots of light into the house... you'd potentially only need the IR emitters pre-show and post-show... perhaps when the ADA devices are not in use?

yeah, I have a bunch of outdoor cameras that switch to IR mode once the ambient light level drops below a certain threshold. Problem is, they take minutes to switch over. If you would just switch off the light, it would probably still take about a minute before IR mode would be activated.

I think it will be better to have a permanent IR source in the room and a camera that supports "passive night vision". Most CMOS and CCD sensors are natively sensitive to IR light, but many cameras have filters that filter out most IR light.

[Daniel Fredrickson]

The IRC emits at 870 nm. I suspect that an IR camera pointed anywhere near it will be severely overloaded, but it would be fun to try out with a borrowed camera. Moving the IRC to the front of the auditorium, where the camera is, would eliminate this problem. The IRC could then serve double duty of providing assistive listening/audio description/closed captions as well as providing IR illumination for the camera.

That makes sense and would probably be the best solution. I am pretty sure I have seen this in a few remodeled Cinemark and AMC auditoriums. Thanks, Harold!

Thanks everyone for the suggestions, we're going to order a few low light cameras and test things out before any commitments. The REOLINK CX810 looks like it might be a good option if properly installed and partitioned from the internet behind a firewall. I'll update the thread if we end up installing something.