achippyland
Posts: 4
Joined: Tue Dec 31, 2019 3:11 am

[SOLVED] Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 3:19 am

SOLVED by @Burngate. Turns out I am dumb and using an IR light separate from the camera causes the reflector to not be seen as the reflector reflects directly back.

The gist of it is that the Pi Noir v2 Camera can see the IR light but with an IR reflector in view it does not seem to be able to distinguish the reflector from the background environment.

I have tried illuminators in the 850nm and 940nm range. I also purchased a 850nm IR filter (effectively blocking out all visible light so the camera is only able to see IR) and it still cannot distinguish the reflector.

I am at a complete loss, any ideas?

EDIT for clarification on attempts
During my testing, the camera can see the IR light in both 850nm and 940nm wavelengths (ie. it does illuminate a dark room). In addition, shining both lights onto the camera shows that it can see the leds illuminated.

I also attempted to only allow IR light into the camera via a filter that only allows >850nm wavelength (ie. IR) light in. When using that, if the illuminators are off, the image shown is completely black, but once the illuminators are turned on the room is lit up, but the reflector is still not distinguishable.

When using another camera such as a Kinect v2 or Wyze security camera, the reflector is visible.
Last edited by achippyland on Tue Dec 31, 2019 11:51 pm, edited 3 times in total.

pcmanbob
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Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 9:59 am

Hi.

As a reflector is a passive device have you got it illuminated with an IR light so it has some thing to reflect ?
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achippyland
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Joined: Tue Dec 31, 2019 3:11 am

Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 2:49 pm

pcmanbob wrote: Hi.

As a reflector is a passive device have you got it illuminated with an IR light so it has some thing to reflect ?
Ah I should have attached photos, but yes I do.

During my testing, the camera can see the IR light in both 850nm and 940nm wavelengths (ie. it does illuminate a dark room). In addition, shining both lights onto the camera shows that it can see the leds illuminated.

I also attempted to only allow IR light into the camera via a filter that only allows >850nm wavelength (ie. IR) light in. When using that, if the illuminators are off, the image shown is completely black, but once the illuminators are turned on the room is lit up, but the reflector is still not distinguishable.

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HermannSW
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Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 4:07 pm

I have played with IR light and Raspberry NoIR cameras, but not with IR reflectors.
What kind of IR reflector do you use?
I searched with DuckDuckGo and aluminum foil seems to be a good IR reflector:
https://www.instructables.com/id/DIY-Ch ... e-Control/
Perhaps you try whether you can achieve the effect you are interested in with a piece of aluminum foil?

P.S:
I once created an alunimum inside triangle tube for focussing 3×5000lm led light -- good to know that this will focus IR light as well:
(I have a powerful 48led IR light: https://www.aliexpress.com/item/32856122386.html -- it allowed to capture 150fps video of fast rotating disk with only 50µs shutter time: https://forum.arduino.cc/index.php?topi ... msg4318521)
https://www.raspberrypi.org/forums/view ... 2#p1428384
Image
⇨https://stamm-wilbrandt.de/en/Raspberry_camera.html

https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/github_repo_i420toh264
https://github.com/Hermann-SW/fork-raspiraw
https://twitter.com/HermannSW

achippyland
Posts: 4
Joined: Tue Dec 31, 2019 3:11 am

Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 6:27 pm

HermannSW wrote:
Tue Dec 31, 2019 4:07 pm
I have played with IR light and Raspberry NoIR cameras, but not with IR reflectors.
What kind of IR reflector do you use?
I searched with DuckDuckGo and aluminum foil seems to be a good IR reflector:
https://www.instructables.com/id/DIY-Ch ... e-Control/
Perhaps you try whether you can achieve the effect you are interested in with a piece of aluminum foil?

P.S:
I once created an alunimum inside triangle tube for focussing 3×5000lm led light -- good to know that this will focus IR light as well:
(I have a powerful 48led IR light: https://www.aliexpress.com/item/32856122386.html -- it allowed to capture 150fps video of fast rotating disk with only 50µs shutter time: https://forum.arduino.cc/index.php?topi ... msg4318521)
https://www.raspberrypi.org/forums/view ... 2#p1428384
Image
It's an interactive wand from Harry Potter world.

I will test with aluminum foil to see if it does show up. I should also note that when using another camera such as a Kinect v2 or Wyze security camera, the reflector is visible.

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Burngate
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Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 6:59 pm

With that last bit of info, I searched and found http://www.williamosman.com/2017/12/hac ... wands.html
It seems it reflects the IR directly back at the LEDs, not towards any camera.

So have you tried moving the LEDs to behind the camera?

achippyland
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Joined: Tue Dec 31, 2019 3:11 am

Re: Noir Camera Does Not Distinguish IR Reflector

Tue Dec 31, 2019 10:58 pm

Burngate wrote:
Tue Dec 31, 2019 6:59 pm
With that last bit of info, I searched and found http://www.williamosman.com/2017/12/hac ... wands.html
It seems it reflects the IR directly back at the LEDs, not towards any camera.

So have you tried moving the LEDs to behind the camera?
Holy smokes, I am an actual idiot.

I think I owe at least two days of my sanity.

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