4 ms·
> like 256 orientations per pixel per image You only need 4 parameters to describe the polarization at a single wavelength[1]. Naively this could be 4 paramete
by planede 2y ago
> like 256 orientations per pixel per image
You only need 4 parameters to describe the polarization at a single wavelength[1]. Naively this could be 4 parameters per color channel, so 12 channels overall. I think you could potentially need more color channels though to capture the full spectrum. But 12 channels at least looks feasible for a camera.
[1] https://en.wikipedia.org/wiki/Stokes_parameters https://en.wikipedia.org/wiki/Stokes_parameters
edit:
On second thought for dealing with reflections you might get away not capturing the "V" Stokes parameter, as you might not care about circular polarization.
edit2:
The I,Q and U parameters can be captured fully by a single polarization filter at three different rotations. This could be feasible with existing cameras with a tripod and a static subject. I wonder if this has been done before.
- cornellwright 2y agoYou can buy [1] polarization cameras, both mono and with a Bayer filter. They're expensive right now, but I agree it would be really cool to see what could be done with a consumer grade version in a smart phone. [1] https://thinklucid.com/product/phoenix-5-0-mp-polarized-model/ https://thinklucid.com/product/phoenix-5-0-mp-polarized-mode... (among many others)
- planede 2y agoInteresting. From what I can find the pixel format is 4 polarization directions per pixel, 45 degrees apart. Even though there are 4 channels this doesn't allow to deduce the V Stokes parameter (this camera can't capture circular polarization). Technically one channel is redundant here, but I guess it can be useful for reducing error. I wonder if an alternative pixel format, with 3 polarization directions 60 degrees apart and a circular polarization channel would be desirable for some applications.
- c0nfused 2y agoWhat is the advantage here vs a polarization filter and a standard camera?
- londons_explore 2y agoYou can capture the whole scene in a single exposure. Handy for moving images.
- im3w1l 2y agoI'm pretty sure he means a single byte-valued parameter. As you mention a single parameter is not enough to fully describe the polarization but maybe it's good enough - I guess you would average across colors, and say circular polarization would lead to a basically random value.
- kloch 2y agoI did indeed mean a singe, byte-valued parameter indicating angle (similar to the single angle parameter of a mechanical polarizing filter) Full polarization and phase info would be great to have also but probably not necessary for reflection suppression. And yes purely circular polarization would be undefined in this scenario but again not common (possible?) with reflections.