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PTGui nadir blend problem

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  • Jean-Marc Paratte
    Hi, I m using PTGui 6.03 and I observe some intensity problem with nadir (and probably it s the same with zenith). How observe problem: I create the panorama
    Message 1 of 5 , Jun 25, 2007
      Hi,

      I'm using PTGui 6.03 and I observe some intensity problem with nadir (and probably it's the same with zenith).

      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.

      Perhaps I can change blending process, what is the good choice?

      I'm using:
      "Correct color layers" selected,
      "Stitch using" PTGui,
      "Blend using" PTGui,
      "use fast transform" selected,
      "Interpolator" Bicubic normal.

      Jean-Marc

      [Non-text portions of this message have been removed]
    • John Houghton
      ... The nadir and zenith areas are difficult to blend and I haven t found any of the blenders to be consistently better than the others. Try Enblend and
      Message 2 of 5 , Jun 26, 2007
        --- In PanoToolsNG@yahoogroups.com, "Jean-Marc Paratte" <jmparatte@...>
        wrote:
        > Perhaps I can change blending process, what is the good choice?

        The nadir and zenith areas are difficult to blend and I haven't found
        any of the blenders to be consistently better than the others. Try
        Enblend and Smartblend - you may find one does better than PTGui. If
        not, take your equirectangular with the view panned down by 90 degrees
        and remap it back to normal orientation with PTGui and be happy! It
        helps to avoid the problem arising in the first place by eliminating
        exposure diferences, vignetting, and dark edges.

        John
      • Bruno Postle
        ... 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,
        Message 3 of 5 , Jun 26, 2007
          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
        • 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 4 of 5 , Jul 1, 2007
            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 5 of 5 , Jul 1, 2007
              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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