4 ms·

- Unlike VR, they don't have to render backgrounds - FOV is apparently their big advantage, along with focus zones - They could do hard occlusion with an LCD

by bobsil1 10y ago

- Unlike VR, they don't have to render backgrounds - FOV is apparently their big advantage, along with focus zones - They could do hard occlusion with an LCD mask. Or they could punt til v2, and soft-occlude with blur using their stacked diffraction plates.

mojomark 10y ago
> - They could do hard occlusion with an LCD mask. Or they could punt til v2, and soft-occlude with blur using their stacked diffraction plates. Unfortunately, you cannot easily achieve "hard occlusion" with an LCD mask. Pinlight display is a project that did explore that idea: http://pinlights.info http://pinlights.info LCDs can attenuate individual rays of light. However, the images we see of real objects in our environment are generated from light in the form of planar wave fronts. So, if you have a near eye LCD micro display and you turn on a single LCD pixel in an attempt to block light emanating from a certain point on a real object, most of the light emanating from that point will simply go around the LCD pixel, enter the pupil and for a point on you retina. The total brightness of the image will dim a little dependant on the size of the LCD pixel, but not by much for a single microdisplay pixel (i.e. a few micron pitch). The Pinlight papers do talk about ways around that issue, using LCD diffraction pattern masks, but I still think the residual diffraction and reduced overall lens transparency associated with the LCD micro display makes the approach an even bigger challenge.
- bobsil1 10y ago
  Depends on size of occluded area? If I block the sun with my thumb, some light does go around, but it's still a decently effective mask.
  - mojomark 10y ago
    If you hold out your thumb between your eye and the sun, such that your thumb appears to just block the edges of the sun, then you will be effectively blocking the entire set of overlapping wavefronts emanating from the sun (that would have formed multiple "pixels" forming the sun image on your retina), preventing their arrival at your cornea and ultimately entering your pupil. Notice that your thumb is about about 1.5ft from your eye. Could you emulate that with a transparent LCD display? Yes, but that display would need to be large and about 1.5ft from your eye. Not really practical for a near eye (head mounted display). If you try to accomplish this occlusion directly with an LCD microdiplay (such as those found in many projectors) in a near eye application, at best you end up with a blackish smudge with very fuzzy edges. To see this in action, look at Figure 11.D in the following paper: http://www.cs.unc.edu/~maimone/media/pinlights_siggraph_2014.pdf http://www.cs.unc.edu/~maimone/media/pinlights_siggraph_2014...
    - bobsil1 10y ago
      Thanks for the paper link. Is there a plausible way to use destructive interference to create true black? I remember patents around this.
      - kelsolaar 10y ago
        Most of the light that is received by the retina in day to day life is highly incoherent thus it is unlikely that you can produce a destructive wavefront for it.
        bobsil1 10y ago
        One of their patents mentions using stacked diffraction optical elements. Details unclear: >[0216] Such may be used to cancel light from the planar waveguides with respect to light from the background or real world, in some respects similar to noise canceling headphones. http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220150016777%22.PGNR.&OS=DN/20150016777&RS=DN/20150016777 http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H...
        mojomark 10y ago
        > One of their patents mentions using stacked diffraction optical elements [DOE]. > http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H.. http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H.... I believe this particular excerpt is referring to the use of the layered and controllable DOEs to curve light projected from their scanning fibers that ultimately forms the virtual object image on the retina, rather than using the DOEs to attenuate ambient light (see my reply to Kelsolaar above). However, if I'm interpreting their literature correctly, you are correct in that they are able to use (at least a portion of) these DOE layers to generate the moire patterns that will ultimately be capable of form black/clear image masks.
        hawski 10y ago
        Would collimator in front help?

by bobsil1 10y ago

mojomark 10y ago

> - They could do hard occlusion with an LCD mask. Or they could punt til v2, and soft-occlude with blur using their stacked diffraction plates. Unfortunately, you cannot easily achieve "hard occlusion" with an LCD mask. Pinlight display is a project that did explore that idea: http://pinlights.info http://pinlights.info LCDs can attenuate individual rays of light. However, the images we see of real objects in our environment are generated from light in the form of planar wave fronts. So, if you have a near eye LCD micro display and you turn on a single LCD pixel in an attempt to block light emanating from a certain point on a real object, most of the light emanating from that point will simply go around the LCD pixel, enter the pupil and for a point on you retina. The total brightness of the image will dim a little dependant on the size of the LCD pixel, but not by much for a single microdisplay pixel (i.e. a few micron pitch). The Pinlight papers do talk about ways around that issue, using LCD diffraction pattern masks, but I still think the residual diffraction and reduced overall lens transparency associated with the LCD micro display makes the approach an even bigger challenge.

bobsil1 10y ago
Depends on size of occluded area? If I block the sun with my thumb, some light does go around, but it's still a decently effective mask.
- mojomark 10y ago
  If you hold out your thumb between your eye and the sun, such that your thumb appears to just block the edges of the sun, then you will be effectively blocking the entire set of overlapping wavefronts emanating from the sun (that would have formed multiple "pixels" forming the sun image on your retina), preventing their arrival at your cornea and ultimately entering your pupil. Notice that your thumb is about about 1.5ft from your eye. Could you emulate that with a transparent LCD display? Yes, but that display would need to be large and about 1.5ft from your eye. Not really practical for a near eye (head mounted display). If you try to accomplish this occlusion directly with an LCD microdiplay (such as those found in many projectors) in a near eye application, at best you end up with a blackish smudge with very fuzzy edges. To see this in action, look at Figure 11.D in the following paper: http://www.cs.unc.edu/~maimone/media/pinlights_siggraph_2014.pdf http://www.cs.unc.edu/~maimone/media/pinlights_siggraph_2014...
  - bobsil1 10y ago
    Thanks for the paper link. Is there a plausible way to use destructive interference to create true black? I remember patents around this.
    - kelsolaar 10y ago
      Most of the light that is received by the retina in day to day life is highly incoherent thus it is unlikely that you can produce a destructive wavefront for it.
      - bobsil1 10y ago
        One of their patents mentions using stacked diffraction optical elements. Details unclear: >[0216] Such may be used to cancel light from the planar waveguides with respect to light from the background or real world, in some respects similar to noise canceling headphones. http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220150016777%22.PGNR.&OS=DN/20150016777&RS=DN/20150016777 http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H...
        mojomark 10y ago
        > One of their patents mentions using stacked diffraction optical elements [DOE]. > http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H.. http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=H.... I believe this particular excerpt is referring to the use of the layered and controllable DOEs to curve light projected from their scanning fibers that ultimately forms the virtual object image on the retina, rather than using the DOEs to attenuate ambient light (see my reply to Kelsolaar above). However, if I'm interpreting their literature correctly, you are correct in that they are able to use (at least a portion of) these DOE layers to generate the moire patterns that will ultimately be capable of form black/clear image masks.
      - hawski 10y ago
        Would collimator in front help?