Depth engine doesn't like black hair and black headset a lot.

[SirLynix]

Describe the bug
When using Azure Kinect with a depth output, the reported depth for my black hair and headset is zero.

To Reproduce
Wear a headset or have black hair, open Azure Kinect Viewer and look at the depth values (or just see the black area) on the depth image.

Expected behavior
I expected Azure Kinect to be able to compute depth in this case, as Kinect for 360 and Kinect for Xbox One don't have this problem.
(also the reported infrared values are not zero but ~80 for my hair and ~40 for my headset, I suspect a threshold).

Screenshots

Desktop (please complete the following information):

• OS with Version: Using Windows 10 2004
• SDK Version: Azure Kinect SDK v1.4.1
• Firmware version:

Current Firmware Versions:
  RGB camera firmware:      1.6.110
  Depth camera firmware:    1.6.79
  Depth config file:        6109.7
  Audio firmware:           1.6.14
  Build Config:             Production
  Certificate Type:         Microsoft

[nachoreimat]

yes, I also noticed missing depth on black/dark objects. Is it a problem of the TOF cameras? maybe those objets/materials do not reflect the laser

[TomHVR]

Maybe there are hairsprays that are more reflective of IR light?

Might be worth taking a piece of glass that is IR transparent, and then trying different hairspray products on them to see which has the most IR reflectivity.

edit: we also use this in film/video production as a temp glare reduction on objects. Wipes off easily, Not sure if I'd want it on my hair though!
https://www.amazon.com/Krylon-K01310-11-Ounce-Dulling-Spray/dp/B00009R8O6?th=1

[qm13]

This is an issue with IR based depth sensors in general. If the material either absorbs or scatters the IR light emitted from the sensor it is not going to see the object. We have heard from a number of customers working in the volumetric film making space that hairspray can address the issue. We have not tested it. Please test it on sample fabric before spraying someone's $200 designer jeans with hairspray.

[SirLynix]

I'm sorry but that doesn't help me, as I'm not going to spray my hair everytime I want to use that camera.

I own all three Kinect models and the Azure is the only one to have this issue. As the reported infrared value is not zero I suppose there's a threshold that discards it.

Could there by any way to let the user adjust that threshold?

[madhan001]

I too have problems with the depth camera not seeing black objects, the kinect v2 I own can perfectly see the object though

[SirLynix]

Please @qm13 consider reopening this issue, as it's not resolved.

[qm13]

This is a matter of physics. Kinect v2 project considerably more light (hence the large power brick) into the operating space than Azure Kinect. We interviewed a number of existing Kinect v2 customers when designing Azure Kinect. One request was smaller or no power brick (achieved) and willingness to this against the operating space. Azure Kinect sensor is more sensitive than Kinect v2 helping limit the reduction in operating space.

There is currently no way to adjust the threshold. I have passed the request to the team working on an improved depth engine.

[TomHVR]

is there potential for introducing a hole filling algorithm?