Selection of polarizing filter for d435f
What kind of polarizing filter film attached to d435 is used in the following paper?
https://dev.intelrealsense.com/docs/optical-filters-for-intel-realsense-depth-cameras-d400
Also, we would like to know if polarizing filters can be used in conjunction with the NIR-cut model d435f.
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Hi @Taiyou24690. Are you referring to the Linear Polarization Filter in section "4.4 When to use polarizers and waveplates" that negates the glare from reflections, please? If you are then any polarising filter should work so long as it is linear. This means that they can be purchased inexpensively from stores such as Amazon by searching for the term 'linear polarization sheet'.
There is no reason why an externally attached filter could not be placed on the outside of the camera to cover the built-in light blocking filter on the filtered 'f' models of RealSense camera, though at the time of writing this there are not currently reports available from other RealSense users about how attaching a linear polarization filter to a D435f would affect the image.
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Thanks for the answer. Yes, I asked about that section.
I am currently considering applying a polarizing filter to the near-infrared spectrum, such as sunlight and incandescent bulbs.Last time I used "K&F Concept Linear Polarizing Film (2 Pieces) A4 Polarized Film Sheets Optical 20x30cm for Screen Educational Physics", but I could not measure the reflected part of sunlight.
I would like to use a polarizing filter with as good a track record as possible as a candidate for a polarizing filter whose polarization band corresponds to the near-infrared region. Please let me know if you have any good candidates.
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Yes, we are also aware that the paper I just mentioned, "While simple and inexpensive linear polarizers can be used in many cases to improve depth quality by suppressing artefacts, we do not include them standard on our cameras for a number of reasons" (Section 4.4), and we understand that it is not included in your product. However, polarizing filters for near-infrared are quite expensive, so it is difficult to try them inexpensively.
If you don't mind, could you please provide more details about the filters used in this paper? -
In 2020 a RealSense team member once recommended a company called Astra Products - https://astraproducts.com/ - as a source for filter products such as ND filters.
https://github.com/IntelRealSense/librealsense/issues/6050#issuecomment-600160086
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Yes, that team member stated in 2020 that Astra did not carry linear polarization filters but I did not know whether that was still the case in the present day.
They recommended not using circular polarizers with RealSense cameras, like those in 3D glasses, but any linear polarizer should be fine.
Aside from Astra Products, Edmund Optics is a company with a long history that carries thin-film linear polarizers.
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