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uclatommy
Up and Coming
July 11, 2013

Achieving natural depth of field

Hold a finger close to your face and look at it. We all know that you'll have double vision for distant objects behind your finger, but you should also notice that the background is blurred.

This effect does not occur in the rift because everything is rendered in focus. Sure, you could add a depth of field to your render, but what happens when you actually look past your finger? The image would converge, but it would be blurry since the computer doesn't know what you're trying to focus on.

I think depth of field is an important visual cue for a sense of space and the rift is lacking this.

But how do we achieve it? I'm no expert at optics, but I believe that your perception of blurriness is because the light entering your eyes reflected from objects at different distances is due to the different angles of incidence. So that got me thinking about whether or not it would be possible to manipulate the angles of light being emitted from individual pixels.

The first thought that comes to mind is to use prisms to do this.

Thoughts? Am I just totally ignorant here? Technically impossible?

    27 replies

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    MrMonkeybat
    Up and Coming
    May 9, 2014
    I always turn off depth of field in games that have it. If the oculus came out with eye tracking that was used by games to create depth of field I would go meh and turn it off. Having sharper focus than a real life camera seems a plus not a negative to me.
    ElectricMucus
    Up and Coming
    May 9, 2014
    "mrmonkeybat" wrote:
    I always turn off depth of field in games that have it. If the oculus came out with eye tracking that was used by games to create depth of field I would go meh and turn it off. Having sharper focus than a real life camera seems a plus not a negative to me.


    That may seem so if there isn't any eye tracking in place.

    In reality depth of field is an important depth cue for your vision. Your brain knows that blurry objects have to be at another distance than the object you are focused on. Our eye distance is way too small for us to only rely on stereoscopic vision and so we have evolved the ability to judge distance with more physical phenomena than is initially obvious.

    So I'd say that depends on the situation of the application. In some cases it might be preferable to always have the vision in focus. But if you are looking to provide a plausible virtual environment or an environment where distance is important to be judged by the user DOF is a key component.
    Of course wrongly implemented or exaggerated DOF can be devastating to the experience and in order to work well it must correspond to physics, so it's not always feasible to implement it in such a way that it can be beneficial.
    mrnitro
    Up and Coming
    September 16, 2015
    That's the way:

    http://www.gizmag.com/stanford-research ... eld/38825/

    :)
    crim3
    Up and Coming
    October 8, 2015
    "mrnitro" wrote:
    That's the way:

    http://www.gizmag.com/stanford-research ... eld/38825/

    :)
    Bingo
    MrMonkeybat
    Up and Coming
    October 10, 2015
    "ElectricMucus" wrote:
    "mrmonkeybat" wrote:
    I always turn off depth of field in games that have it. If the oculus came out with eye tracking that was used by games to create depth of field I would go meh and turn it off. Having sharper focus than a real life camera seems a plus not a negative to me.


    That may seem so if there isn't any eye tracking in place.

    In reality depth of field is an important depth cue for your vision. Your brain knows that blurry objects have to be at another distance than the object you are focused on. Our eye distance is way too small for us to only rely on stereoscopic vision and so we have evolved the ability to judge distance with more physical phenomena than is initially obvious.

    So I'd say that depends on the situation of the application. In some cases it might be preferable to always have the vision in focus. But if you are looking to provide a plausible virtual environment or an environment where distance is important to be judged by the user DOF is a key component.
    Of course wrongly implemented or exaggerated DOF can be devastating to the experience and in order to work well it must correspond to physics, so it's not always feasible to implement it in such a way that it can be beneficial.


    If you dont have a true light field display its not worth it. Fake bluring of the screen when it is really at the same focal distance is only going to exacerbate the accommodation reflex conflict. Tracking the depth your eyes are converging at will require much more accurate eye tracking than that needed for foveated rendering. In photographs you have learned that you can judge foreground and background from the focusing but in real life your eye refocuses very quickly to whatever you are looking at the eye muscles exercising provide some depth hints, but fake blurring will only confuse it. The human eye also has a pretty deep focal plane between things beyond arm length the amount of blurring is less than the angular resolution on curent HMDs. During the day hold up you hand at arms length against the horizon the amount of bluring between the two is quite minor. And as you can only see clearly with the 4 degrees of your fovea the situations when things with such great distances between them are both inside you fovea are really quite rare.
    tonyLongson
    New Participant
    October 30, 2015
    It seems to me that there is some confusion about what is being discussed.

    Depth of field is a camera lens effect which occurs when the lens has a large aperture (usually because light levels are low).

    The apparent doubling of images at distances different from the focus of attention is a result of convergence. Anything in the field of view that we are not converging on will to some extent appear as a double image. This is very clearly a component of natural vision, and it is not replicated in any kind of stereo images; being flat, they have just a single focal plane.

    Neither phenomenon could be simulated with eye tracking which measures eye convergence, as the eyes are focusing on a flat plane - the VR screen, the eye convergence is always the same.

    However, tracking to see what object the viewer is looking at, figuring out how far away it is, and changing the display of everything else (depth of field, and faking convergence artefacts) could work.

    Is anyone working on this ?
    tonyLongson
    New Participant
    October 31, 2015
    This is very clearly a component of natural vision, and it is not replicated in any kind of stereo images; being flat, they have just a single focal plane.

    Neither phenomenon could be simulated with eye tracking which measures eye convergence, as the eyes are focusing on a flat plane - the VR screen, the eye convergence is always the same.


    Sorry... obviously wrong about this. I was forgetting the difference between the two images..
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