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Re: Stereo distortions in stereo panoramas

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  • Wim Koornneef
    ... Hello Enrique, For a 3D pano with no objects closeby and only far away objects you have to seperate the camera lenses wider to get more parallax otherwise
    Message 1 of 18 , Feb 2, 2011
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      enridp wrote:
      > ... if we are shooting far objects, like a landscape, could we shoot only
      > the common 4 images (for sigma8mm) for example?...

      Hello Enrique,

      For a 3D pano with no objects closeby and only far away objects you have to
      seperate the camera lenses wider to get more parallax otherwise there is no
      depth in the 3D view.

      So instead of 9 cm, 25, 50 cm or even more lens seperation, depending on the
      distance to far away objects, can be needed.
      With such extreme lens seperations (hyper stereo) the NPP off set is really,
      really huge and with just 4 images around it will cause huge stitch errors
      in each of the left and right pano.
      To tackle this probem you really have to shoot a lot more then 4 images.

      In general; the more images you shoot the smaller the stitch errors will be,
      this is because the total amount of parallax error wil be evenly spread over
      all images. The number of images that are needed depends on the amount of
      stitching errors that *you* find acceptable......

      Wim
      --
      View this message in context: http://panotoolsng.586017.n4.nabble.com/Stereo-distortions-in-stereo-panoramas-tp3246722p3253601.html
      Sent from the PanoToolsNG mailing list archive at Nabble.com.
    • enridp
      Thanks Wim !!! You are right about the extra separation (and hence the extra parallax error) needed for very far objects. But I m a bit confused now of why
      Message 2 of 18 , Feb 2, 2011
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        Thanks Wim !!!
        You are right about the extra separation (and hence the extra parallax error) needed for very far objects.

        But I'm a bit confused now of why earthmine is using two cameras, and with big separation:

        http://www.freeimagehosting.net/image.php?3f93db70f8.jpg

        They have the best "street view" system in the market I think, with a very accurate 3D (although there are only videos about earthmine, I couldn't find any online demo or something like that).



        --- In PanoToolsNG@yahoogroups.com, Wim Koornneef <wim.koornneef@...> wrote:
        >
        >
        >
        > enridp wrote:
        > > ... if we are shooting far objects, like a landscape, could we shoot only
        > > the common 4 images (for sigma8mm) for example?...
        >
        > Hello Enrique,
        >
        > For a 3D pano with no objects closeby and only far away objects you have to
        > seperate the camera lenses wider to get more parallax otherwise there is no
        > depth in the 3D view.
        >
        > So instead of 9 cm, 25, 50 cm or even more lens seperation, depending on the
        > distance to far away objects, can be needed.
        > With such extreme lens seperations (hyper stereo) the NPP off set is really,
        > really huge and with just 4 images around it will cause huge stitch errors
        > in each of the left and right pano.
        > To tackle this probem you really have to shoot a lot more then 4 images.
        >
        > In general; the more images you shoot the smaller the stitch errors will be,
        > this is because the total amount of parallax error wil be evenly spread over
        > all images. The number of images that are needed depends on the amount of
        > stitching errors that *you* find acceptable......
        >
        > Wim
        > --
        > View this message in context: http://panotoolsng.586017.n4.nabble.com/Stereo-distortions-in-stereo-panoramas-tp3246722p3253601.html
        > Sent from the PanoToolsNG mailing list archive at Nabble.com.
        >
      • Aldo Hoeben
        ... That s not for stereo, but for accurately measuring distances through triangulation. Note that *your* eyes are arranged in a horizontal configuration.
        Message 3 of 18 , Feb 2, 2011
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          > But I'm a bit confused now of why earthmine is using two cameras,
          > and with big separation:
          >
          > http://www.freeimagehosting.net/image.php?3f93db70f8.jpg

          That's not for stereo, but for accurately measuring distances through triangulation. Note that *your* eyes are arranged in a horizontal configuration.
        • enridp
          Yes, but why is so important the orientation of the camera?, you can rotate your head 90 degrees and still viewing in 3D. Is not possible to arrage the camera
          Message 4 of 18 , Feb 2, 2011
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            Yes, but why is so important the orientation of the camera?, you can rotate your head 90 degrees and still viewing in 3D.
            Is not possible to arrage the camera in a vertical configuration like earthmine? in tha way we will be rotating both cameras from their NPP.



            --- In PanoToolsNG@yahoogroups.com, "Aldo Hoeben" <aldo@...> wrote:
            >
            > > But I'm a bit confused now of why earthmine is using two cameras,
            > > and with big separation:
            > >
            > > http://www.freeimagehosting.net/image.php?3f93db70f8.jpg
            >
            > That's not for stereo, but for accurately measuring distances through triangulation. Note that *your* eyes are arranged in a horizontal configuration.
            >
          • Aldo Hoeben
            ... If that is how you want to view your images, then by all means arrange your cameras in a vertical orientation instead of horizontal. But it sounds mighty
            Message 5 of 18 , Feb 3, 2011
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              > Yes, but why is so important the orientation of the camera?, you
              > can rotate your head 90 degrees and still viewing in 3D.

              If that is how you want to view your images, then by all means arrange your cameras in a vertical orientation instead of horizontal. But it sounds mighty uncomfortable to me ;-)

              Earthmine uses the two cameras to be able extract actual 3d geometry from the pair of images. To do this with accuracy, the requirement is to know the exact distance between the two cameras, but it is not all that important how the cameras are arranged. If however they would put the cameras side-to-side, one camera would obscure part of the view of the other camera and vice versa. Ofcourse this still happens with the vertical arrangement, but for this application the zenith and nadir are not that interesting.

              Stereo capture and viewing is something altogether different. For that the cameras need to mimick what the eyes do. IE: the two cameras (arranged horizontally) would need to rotate around a single shared point. If you were to use two one-shot systems, you would have the aforementioned problem that the two cameras see eachother when looking to the sides (left camera sees the right camera when looking right). Additionally things will get screwy if you look backwards in the panorama; the left and right "eye" will be swapped. Two one-shots are just not going to work.

              Having said all that, if earthmine would indeed create accurate 3d geometry from their capture, it would be possible - in theory - to create stereo pairs out of that. But that requires A LOT of processing, and even then the result would be a far cry from what Peter has achieved lately with his stereo spinner work.
            • enridp
              Yes you are right, If we have the cameras in vertical configuration then the red and cyan will be up and down not at the sides, even after rotation of the
              Message 6 of 18 , Feb 3, 2011
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                Yes you are right, If we have the cameras in vertical configuration then the red and cyan will be up and down not at the sides, even after rotation of the images.
                (an easy test, rotate your head with any Stereo Image and you can see how the effect is lost)

                And the Stereo images from images with 3D information (distance of each pixel) could work, but the effect will not "volumetric" I think.
                I mean, we will see different planes at different distances, not objects with volume.
                That's what happens with "Fake3D" movies:
                http://realorfake3d.com/


                --- In PanoToolsNG@yahoogroups.com, "Aldo Hoeben" <aldo@...> wrote:
                >
                > > Yes, but why is so important the orientation of the camera?, you
                > > can rotate your head 90 degrees and still viewing in 3D.
                >
                > If that is how you want to view your images, then by all means arrange your cameras in a vertical orientation instead of horizontal. But it sounds mighty uncomfortable to me ;-)
                >
                > Earthmine uses the two cameras to be able extract actual 3d geometry from the pair of images. To do this with accuracy, the requirement is to know the exact distance between the two cameras, but it is not all that important how the cameras are arranged. If however they would put the cameras side-to-side, one camera would obscure part of the view of the other camera and vice versa. Ofcourse this still happens with the vertical arrangement, but for this application the zenith and nadir are not that interesting.
                >
                > Stereo capture and viewing is something altogether different. For that the cameras need to mimick what the eyes do. IE: the two cameras (arranged horizontally) would need to rotate around a single shared point. If you were to use two one-shot systems, you would have the aforementioned problem that the two cameras see eachother when looking to the sides (left camera sees the right camera when looking right). Additionally things will get screwy if you look backwards in the panorama; the left and right "eye" will be swapped. Two one-shots are just not going to work.
                >
                > Having said all that, if earthmine would indeed create accurate 3d geometry from their capture, it would be possible - in theory - to create stereo pairs out of that. But that requires A LOT of processing, and even then the result would be a far cry from what Peter has achieved lately with his stereo spinner work.
                >
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