Requirement of lighting environment for sensing using D435 and D415

[shige]

I am evaluating depth sensing using D435 and D415.

We have to hide camera lens from user using various NIR filters, it's customer request.

We would like to track gesture on poor lighting environment, also it may have no lighting.

I have a question, are there effect to accuracy of depth sensing on such environment, it only have to project IrDA to intended object ?

[MartyG]

If the lighting is poor / absent then you may have to rely on the IR Projector component, which projects a semi-random pattern of dots onto a scene to add 'texture' to it and make its depth more readable by the camera.

A consequence of using the IR Emitter is that you may get a 'speckle' pattern of noise on the image. This can be reduced by using an external LED projector instead of the built-in laser projector, though I understand that an external projector may not be practical in your application.

The image below shows an example of an LED dot pattern projector being used in a dark room.

I would think that you would have difficulty tracking a hand or face gesture in a dark room though, as the dot pattern is not likely to help the camera to read hand joint or facial landmark information.

I wonder if a more effective solution might be to use a cover material for the camera that is made from one-way glass, so that it lets light pass through it into the camera lens but a person outside of the glass cannot see the camera behind it. It can be obtained as a film that can be applied to ordinary glass.

https://www.lustalux.co.uk/refurb-films/one-way-window-film

[shige]

Thank you,

Does D400 series have only a capability of IR emitting on/off ? Are there any feature for prevention of Specle ?

Our use case, one-way glass may not be permitted by customer, because mirror is

[shige]

Sorry, mistake.

​Our use case, one-way glass may not be permitted by customer, because mirror is not accepted by them.

[MartyG]

As well as turning the Emitter on or off, the 400 Series can also alter the visibility of the dot pattern with its Laser Power setting. The lower the Laser Power value, the less visible that IR dot projection becomes. Laser Power = 0 should be equal to the dot pattern being disabled.

D415 cameras have the additional option of a 'Left Imager Color w/o IR Pattern' selectable configuration that removes the dot pattern.

https://github.com/IntelRealSense/librealsense/wiki/D400-Series-Visual-Presets#preset-table

In regard to laser speckle, Intel's excellent illustrated camera tuning guide says "Non coherent light sources will lead to best results in terms of depth noise, but cannot normally generate as high contrast pattern at long range".

https://realsense.intel.com/wp-content/uploads/sites/63/BKM-For-Tuning-D435-and-D415-Cameras-Webinar_Rev3.pdf