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Re: New/Old Approach to panoramic videos

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  • Erik Krause
    ... I wouldn t be too optimistic: 4k means the shorter side has about 2300 pixels. Since the fisheye image needs to be circular this is the maximum diameter of
    Message 1 of 6 , Apr 17, 2013
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      Am 17.04.2013 11:38, schrieb Roger D Williams:
      > That is quite high enough to enable rectilinear images with viable
      > resolution for web display use to be extracted from the video
      > stream.

      I wouldn't be too optimistic: 4k means the shorter side has about 2300
      pixels. Since the fisheye image needs to be circular this is the maximum
      diameter of the image circle. We can assume the images will have about
      2000 pixels per 180° giving a maximum equirect size of 4000x2000 pixels
      or a pixel density of 11.1 px/degree.

      The classical 50mm standard lens on a full frame camera delivers 39°x26°
      angles of view. That would give images with roughly 430x280px.

      For wider angles you get more pixels, but not the full amount because of
      the perspective distortion which causes pixel stretching outside the
      middle. A 90° extracted image will have 900px (instead of 1000), a super
      wide 120° extracted image (which will suffer from severe perspective
      distortion) will have 1100px (instead of 1333).

      --
      Erik Krause
      http://www.erik-krause.de
    • Roger D Williams
      Ah yes, I see. Only 2,300? But the way it is described, the 4K is the size of the equirectangular image output, which is a rather different kettle of fish, no?
      Message 2 of 6 , Apr 18, 2013
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        Ah yes, I see. Only 2,300? But the way it is described, the 4K is the size of the equirectangular image output, which is a rather different kettle of fish, no?

        Roger

        Sent from my iPad

        On Apr 18, 2013, at 7:03 AM, Erik Krause <erik.krause@...> wrote:

        > Am 17.04.2013 11:38, schrieb Roger D Williams:
        >> That is quite high enough to enable rectilinear images with viable
        >> resolution for web display use to be extracted from the video
        >> stream.
        >
        > I wouldn't be too optimistic: 4k means the shorter side has about 2300
        > pixels. Since the fisheye image needs to be circular this is the maximum
        > diameter of the image circle. We can assume the images will have about
        > 2000 pixels per 180‹ giving a maximum equirect size of 4000x2000 pixels
        > or a pixel density of 11.1 px/degree.
        >
        > The classical 50mm standard lens on a full frame camera delivers 39‹x26‹
        > angles of view. That would give images with roughly 430x280px.
        >
        > For wider angles you get more pixels, but not the full amount because of
        > the perspective distortion which causes pixel stretching outside the
        > middle. A 90‹ extracted image will have 900px (instead of 1000), a super
        > wide 120‹ extracted image (which will suffer from severe perspective
        > distortion) will have 1100px (instead of 1333).
        >
        > --
        > Erik Krause
        > http://www.erik-krause.de
        >
        >
        > ------------------------------------
        >
        > --
        >
        >
        >
      • Erik Krause
        ... Yes, since the equirect consists of two fisheye images each one covering 180‹with 2000px in diameter the equirect will have 4000x2000px. -- Erik Krause
        Message 3 of 6 , Apr 18, 2013
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          Am 18.04.2013 12:23, schrieb Roger D Williams:
          > Ah yes, I see. Only 2,300? But the way it is described, the 4K is the
          > size of the equirectangular image output, which is a rather different
          > kettle of fish, no?

          Yes, since the equirect consists of two fisheye images each one covering
          180°with 2000px in diameter the equirect will have 4000x2000px.

          --
          Erik Krause
          http://www.erik-krause.de
        • Adrien Fontvielle
          High Roger, do you have a link to this article/company? Best regards, Adrien Adrien Fontvielle 2013/4/18 Erik Krause ... High Roger, do
          Message 4 of 6 , Apr 22, 2013
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            High Roger,
            do you have a link to this article/company?
            Best regards,
            Adrien

            Adrien Fontvielle


            2013/4/18 Erik Krause <erik.krause@...>
            Am 18.04.2013 12:23, schrieb Roger D Williams:
            > Ah yes, I see. Only 2,300? But the way it is described, the 4K is the
            > size of the equirectangular image output, which is a rather different
            > kettle of fish, no?

            Yes, since the equirect consists of two fisheye images each one covering
            180°with 2000px in diameter the equirect will have 4000x2000px.

            --
            Erik Krause
            http://www.erik-krause.de


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          • Roger D. Williams
            Only to a photograph of the original Japanese article. If that would be any help I can look it up, but it was not easy for me to read and I have been a
            Message 5 of 6 , Apr 22, 2013
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              Only to a photograph of the original Japanese article. If that would be any
              help I can look it up, but it was not easy for me to read and I have been a
              translator from Japanese for most of my working life!

              Roger


              On Mon, 22 Apr 2013 21:27:14 +0900, Adrien Fontvielle <fontviea@...> wrote:



              High Roger,
              do you have a link to this article/company?
              Best regards,
              Adrien

              Adrien Fontvielle


              2013/4/18 Erik Krause <erik.krause@...>
              Am 18.04.2013 12:23, schrieb Roger D Williams:
              > Ah yes, I see. Only 2,300? But the way it is described, the 4K is the
              > size of the equirectangular image output, which is a rather different
              > kettle of fish, no?

              Yes, since the equirect consists of two fisheye images each one covering
              180°with 2000px in diameter the equirect will have 4000x2000px.

              --
              Erik Krause
              http://www.erik-krause.de


              ------------------------------------

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