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RE: [PanoToolsNG] PTGui nadir blend problem

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  • Jean-Marc Paratte
    In the background of the problem, you are true when you tell us about Basically any tool that ... But revise you opinion. We are speaking about problems of
    Message 1 of 5 , Jul 1 12:08 PM
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      In the background of the problem, you are true when you tell us about
      "Basically any tool that ..."

      But revise you opinion.

      We are speaking about problems of blending of equirectangular pictures.

      Equirectangular pictures are perfectly defined in any parts of the sphere,
      if we understand that those images are defined in nadir and zenith
      in the same manner as at the -180 and +180° limits, by looping the picture,
      simply apply the same process at -90 and +90° limits of vertical axis.
      But I think it's more difficult to apply on vertical axis else on horizontal
      axis.

      I wish a solution for this problem because I assemble nadir without nadir
      shot,
      simply by tilting down all shots. With a nadir shot, the problem is
      eliminated
      and rejected to other parts of images with less or no blending problems.

      Jean-Marc



      -----Original Message-----
      From: PanoToolsNG@yahoogroups.com [mailto:PanoToolsNG@yahoogroups.com]On
      Behalf Of Bruno Postle
      Sent: Tuesday, June 26, 2007 11:25 PM
      To: PanoTools NG
      Subject: Re: [PanoToolsNG] PTGui nadir blend problem


      On Tue 26-Jun-2007 at 07:57 +0200, Jean-Marc Paratte wrote:
      >
      > How observe problem: I create the panorama by the normal way ==>
      > intensity problem in nadir, like waves of lighting between each
      > sources images, and when I apply a final pitch of -90° (the nadir
      > face becomes the front face), nadir looks good.

      This isn't a ptgui bug, it's a general problem associated with
      equirectangular images.

      Basically any tool that operates on a fixed radius: blurring,
      scaling, sharpening, paint-brushes, local tonemapping, feathering
      (and enblend which is just super-feathering) - Is going to produce
      strange effects in the zenith and nadir of an equirectangular image.

      So in general: avoid stitching equirectangular panoramas where seams
      are near the poles, use the numerical transform to tilt the scene if
      necessary. Avoid heavy use of scaling, blurring and sharpening -
      Some is ok, but scaling a 10000x5000 panorama to 2000x1000 is going
      to create very ugly artefacts in the zenith and nadir.

      --
      Bruno





      [Non-text portions of this message have been removed]
    • Bruno Postle
      ... This is the alternative technique, rotating the panorama to keep the seams away from the zenith and nadir:
      Message 2 of 5 , Jul 1 1:43 PM
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        On Sun 01-Jul-2007 at 21:08 +0200, Jean-Marc Paratte wrote:

        > I wish a solution for this problem because I assemble nadir
        > without nadir shot, simply by tilting down all shots. With a nadir
        > shot, the problem is eliminated and rejected to other parts of
        > images with less or no blending problems.

        This is the alternative technique, rotating the panorama to keep the
        seams away from the zenith and nadir:

        http://wiki.panotools.org/Philopod_pitch_variation

        --
        Bruno
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