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Problem when displaying object at close distance

Discussion in 'AR/VR (XR) Discussion' started by NeuroImmersion, Oct 22, 2018.

  1. NeuroImmersion

    NeuroImmersion

    Joined:
    Jan 17, 2018
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    3
    Hello,

    I am currently trying to run an experiment in stereoscopy using Unity and a 3D projector. The experiment consist on displaying objects far and close (under grabbing distance) from the subject. I am having trouble displaying the object in close distance. The experiment will take place in an fMRI, so we can not use HMD.

    When displaying object at close distance, the subject perceive the object as split into two. If I try to reduce this gap, the subject will perceive the object well but too far for the experiment purpose.

    I tried to modify the StereoConvergence and StereoSeparation (Unity 2017.4) but I could not solve this issue. Is there a optimal set of value for those parameters ?

    I also tried the Nvidia stereoscopic demo and it worked fine, we got a good perception of the Nvidia logo at close distance. Is there a limitation in Unity ?

    Running on VPixx 3D projector, Windows 10, Nvidia GTX 1060, Intel i7.
     
  2. JoeStrout

    JoeStrout

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    Jan 14, 2011
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    7,909
    It's unlikely this is a Unity limitation. I'm not familiar with that 3D projector, but whether it's using polarized filter glasses or shutter glasses, it should be very easy to actually measure the separation of the projected image, and compare this to the expected separation (which you can calculate by hand).

    For that matter, perhaps you can grab that Nvidia logo, and try to place it at the same virtual position in your Unity project, and then directly compare the results. How does the Unity result differ?
     
  3. NeuroImmersion

    NeuroImmersion

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    Jan 17, 2018
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    Thank for your answer. I will try this, and come back with the result.
     
    JoeStrout likes this.
  4. NeuroImmersion

    NeuroImmersion

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    Jan 17, 2018
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    After further investigation, it appears that I was not trying to solve the right problem. The effect of split on the object was more a problem of ghosting, instead of an issue about converging on the image. The ghosting effect was due to the high contrast between the object and the background of the scene.

    Now we try to have the subject perceived the object at a precise distance around 50 cm for the close and more than 3m for the far stimulus.
    Is there some good pratice on how to set up the stereoConvergence value on the camera ? For the StereoSeparation, we use a value of 0,06 that corresponds to a medium value of among human eye's separation.