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What is the basic principle behind this approach. A lens essentially allows you to map light rays (which have an origin and a direction vector) to position on

What is the basic principle behind this approach. A lens essentially allows you to map light rays (which have an origin and a direction vector) to position on the sensor (a pinhole does the same but lets through much less light). Did Lytro have a sensor that could actually measure both the position and direction of an incident light ray ?

NovemberWhiskey 4y ago
IIRC there was a micro-lens array between the objective lens and the sensor; each of the micro lenses added a separate, overlapping contribution on the sensor and with a bunch of signal processing magic you somehow back out the position/direction. Reading the article, I don't at all see what the difference is between the Lytro camera and what's described there - although I'm not an optics expert.
- tgflynn 4y ago
  One difference may be that, as I recall, Lytro was focused on (2D) photography, while this seems to be targeting 3D, which may be a much more compelling application.
  - NovemberWhiskey 4y ago
    I don't know - it seems pretty much the same - the whole point of the Lytro camera was that you had sufficient information in the recorded image to select your point of focus and depth in post-processing, which is essentially the same as having depth data.
    - tgflynn 4y ago
      The same information is used but there's a big difference between using it to make prettier photos versus reconstructing 3D scenes. The second application domain seems to have much more potential for revolutionary change than the first (to me at least). The average person, or probably even the average VC, isn't going to read a pitch about being able to take photos without having to adjust lens focus and say "gee, with that technology you could build a 3D model as easily as taking a photo".
jbay808 4y ago
You more or less described it. If you put a microlens over, say, each 3x3 pixel sub-array, then each of those 3x3 squares now captures a locally incident light ray and its direction (with low resolution). You can now treat that as a single image pixel, but now containing angular information describing how that pixel changes with rotation in the field of view. Effectively you end up with an array of tiny cameras. Applying the same principle in reverse, you can also create a 3D display by adding a microlens array on top of an image. If you use the same microlens array to capture the image as to display it (swapping out the sensor with a display, or a camera film with its developed photograph) then optical physics does all the necessary image processing for you. The idea goes back at least as far as Gabriel Lippmann in the 1900s: https://en.wikipedia.org/wiki/Lenticular_printing#Gabriel_Lippmann's_integral_photography https://en.wikipedia.org/wiki/Lenticular_printing#Gabriel_Li...

NovemberWhiskey 4y ago

IIRC there was a micro-lens array between the objective lens and the sensor; each of the micro lenses added a separate, overlapping contribution on the sensor and with a bunch of signal processing magic you somehow back out the position/direction. Reading the article, I don't at all see what the difference is between the Lytro camera and what's described there - although I'm not an optics expert.

tgflynn 4y ago
One difference may be that, as I recall, Lytro was focused on (2D) photography, while this seems to be targeting 3D, which may be a much more compelling application.
- NovemberWhiskey 4y ago
  I don't know - it seems pretty much the same - the whole point of the Lytro camera was that you had sufficient information in the recorded image to select your point of focus and depth in post-processing, which is essentially the same as having depth data.
  - tgflynn 4y ago
    The same information is used but there's a big difference between using it to make prettier photos versus reconstructing 3D scenes. The second application domain seems to have much more potential for revolutionary change than the first (to me at least). The average person, or probably even the average VC, isn't going to read a pitch about being able to take photos without having to adjust lens focus and say "gee, with that technology you could build a 3D model as easily as taking a photo".

jbay808 4y ago

You more or less described it. If you put a microlens over, say, each 3x3 pixel sub-array, then each of those 3x3 squares now captures a locally incident light ray and its direction (with low resolution). You can now treat that as a single image pixel, but now containing angular information describing how that pixel changes with rotation in the field of view. Effectively you end up with an array of tiny cameras. Applying the same principle in reverse, you can also create a 3D display by adding a microlens array on top of an image. If you use the same microlens array to capture the image as to display it (swapping out the sensor with a display, or a camera film with its developed photograph) then optical physics does all the necessary image processing for you. The idea goes back at least as far as Gabriel Lippmann in the 1900s: https://en.wikipedia.org/wiki/Lenticular_printing#Gabriel_Lippmann's_integral_photography https://en.wikipedia.org/wiki/Lenticular_printing#Gabriel_Li...