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Re: Pano2VR makes different default cubefaces

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  • fierodeval
    Hi Thomas, But, if the default value is width/4 you are using this figure: http://www.devalvr.com/fiero/equicube2.jpg , loosing a lot of information in the
    Message 1 of 11 , Nov 2, 2008
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      Hi Thomas,

      But, if the default value is width/4 you are using this figure:
      http://www.devalvr.com/fiero/equicube2.jpg , loosing a lot of
      information in the conversion.

      If you take the output equirect from PTGui, all values superior to
      3.14 in the divisor are loosing information in the conversion.

      regards!
      fiero



      --- In PanoToolsNG@yahoogroups.com, Thomas Rauscher <yahoo@...> wrote:
      >
      > fierodeval wrote, On 01.11.2008 21:59 Uhr:
      > > Yes, I understand. But when you speak about the "sqrt(2)", you are
      > > speaking about the figure in the right of this image
      > > http://www.devalvr.com/fiero/equicube.jpg . Te correct figure is in
      > > the left and this figure is valid in the two directions.
      > >
      > > Then, if I understand correctly, you say that the figure for
      > > equirect->cube conversion is the left image and for cube->equirect is
      > > the right image?
      >
      > Yes. correct. Because the cube faces *could* contain more
      information in
      > the corners.
      >
      > If the source was a equirectangular with 1/Pi as factor for the cube
      > faces size then it is safe to just use the left type of conversion
      again
      > because the pixels in corners are stretched by a factor of sqrt(2).
      >
      > If the source images are cube faces, for example of a rendering from a
      > 3D software, then you need to use the conversion on the right side to
      > avoid losing resolution/information.
      >
      > The factor Pi*sqrt(2) would also be true if the equi->cube was executed
      > with a factor smaller then 1/Pi*sqrt(2) to get the maximum out of the
      > cube faces. Another case would be if you recover a equirectangular
      from
      > a QTVR where you don't know the original resolution.
      >
      > --
      > MfG,
      > Thomas
      >
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