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Re: Remapping question

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  • Erik Krause
    ... Just an estimate: 2000px cube face width has the same resolution as 6282px equirectangular width. You can do little planet with a 360° fisheye mapping
    Message 1 of 3 , Nov 2, 2009
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      Robert Slade wrote:

      > I have a Pano2VR project with input of six cube faces of 2000x2000
      > pixels each.
      >
      > I want to create a transformation to an angular map "little planet"
      > (circular).
      >
      > How do I calculate the maximum resolution possible given the size of the
      > cube faces?

      Just an estimate: 2000px cube face width has the same resolution as
      6282px equirectangular width. You can do "little planet" with a 360°
      fisheye mapping which would be the same width as the equirect. It very
      much looks as if Pano2VR uses this mapping.

      However, the better mapping for "little planet" is stereographic, which
      stretches the outer regions. PTGui f.e. suggest 300° for "little planet"
      with about 14000px for a 6000px wide input equirect...

      Perhaps you find some more info following the links on
      http://wiki.panotools.org/Stereographic_Projection.

      best regards
      --
      Erik Krause
      http://www.erik-krause.de
    • Erik Krause
      ... The formula is quite simple: 2 * equirect width * tan(FoV/4) / pi The result is the stereographic image width and FoV is the angle of the desired field
      Message 2 of 3 , Nov 2, 2009
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        Erik Krause wrote:

        > However, the better mapping for "little planet" is stereographic, which
        > stretches the outer regions. PTGui f.e. suggest 300° for "little planet"
        > with about 14000px for a 6000px wide input equirect...

        The formula is quite simple:

        2 * equirect width * tan(FoV/4) / pi

        The result is the stereographic image width and "FoV" is the angle of
        the desired field of view of the stereographic image.

        However, Pano2VR most likely doesn't use this mapping but the fisheye
        one, where the output image width is the same as the equirect image width.

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