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Re: Consistent stitching errors

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  • John Houghton
    ... This suggests that the lateral positioning of the camera is not correct. The entrance pupil may be located correctly front to back, but not side to side.
    Message 1 of 8 , Nov 30, 2006
      --- In PanoToolsNG@yahoogroups.com, Blake Michaelson
      <blake.michaelson@...> wrote:
      >
      > Imagine a nautilus shell put on its side, and shifted 60° about
      > it's "nodal point" - there's a bit of a lip from each pano image
      > that contributes to making the circle look a bit like a pinwheel...
      > if you can imagine what I'm attempting to describe.

      This suggests that the lateral positioning of the camera is not
      correct. The entrance pupil may be located correctly front to back,
      but not side to side. Whatever instructions you are following, they
      don't seem to have worked. Try checking the entrance pupil position
      visually using this simple arrangement:
      http://homepage.ntlworld.com/j.houghton/eppos.jpg
      Point the eyepiece at a bright light source to illuminate the
      entrance pupil. Make sure you have the pano head level and use the
      plumb line to check that the entrance pupil is centered on the axis
      point.

      Generally, there is no requirement to accurately level the panorama
      head and/or the camera to ensure good stitching. Rotating the camera
      about the no-parallax point is the important thing to get right.

      John
    • Sacha Griffin
      There s no way to know really without the original images and your project file where the flaw is in your system. I ve used an identical setup as yours, and
      Message 2 of 8 , Nov 30, 2006
        There's no way to know really without the original images and your project
        file where the flaw is in your system.

        I've used an identical setup as yours, and consistently get under 1 pixel of
        error average with a max error of no more than 1.5 or 2.

        There are literally a dozen or more points of failure and this could turn
        into a dangerous thread of conjecture.

        You can browse past messages here for many many useful hints but I advise to
        post everything somewhere so we can take a look.

        Sacha Griffin
        Southern Digital Solutions LLC
        www.southern-digital.com
        www.seeit360.net
        www.ezphotosafe.com
        404-551-4275
        404-731-7798


        -----Original Message-----
        From: Blake Michaelson [mailto:blake.michaelson@...]
        Sent: Thursday, November 30, 2006 3:57 AM
        To: PanoToolsNG@yahoogroups.com
        Subject: [PanoToolsNG] Consistent stitching errors

        Hello,

        I've been searching for a resolution to some consistent stitching errors
        without success - I'm hoping I can gain some insight from some of the
        sage here... Forgive me if this is a bit lengthy, but I wanted to
        ensure I accurately represented the issue.

        I am using a Canon 350D with the Peleng 8mm EOS, a Panosaurus head,
        Bogen 3012B Legs and 486RC2 (with RC2 removable plate) - my first
        instinct is to immediately jump on the panosaurus as the culprit, but I
        don't want to be too quick to judge.

        The consistent problem I am having with the stitching errors is that,
        regardless of the number of images I take (4/6/8/12) I have a
        significant amount of deviation on my control point table. Were I to
        take 4 shots plus Z & N, import them into PTGui (basic mode) and align
        them - my results would be: Average control point distance 8.3524,
        minimum 0.6301, maximum 30.7133 - this is a typical spread for any given
        series of images. Although this isn't too detrimental when taking
        outdoor panos, it is a significant issue when taking indoor panos.

        I have found that I can decrease the spread, i.e. improve the tightness
        of the table, by removing and nadir - marginally, but some - say an
        average of 5.0 for the control points, and a little bit more by removing
        the zenith. The biggest gain is accomplished by simply removing the nadir.

        I have attempted to clean up my control point table by deleting high
        value points, and re-optimizing the table, eventually ending up with
        very few control points, but a "very good" optimization with a max
        distance control point of less than 5.0. Regardless, the same stitching
        issues remain.

        The actual stitching issue is typically a highly visible vertical
        "smudge" or alignment issue on a horizontal surface (i.e. a ceiling
        seam, a structural beam) or simply a skewed vertical stitch placed in
        the middle of a cabinet or wall. As an aside - I had nearly no such
        issues with the same legs, head, camera setup using the 18-55 kit lens
        set to 18mm using 3 rows of 12 shots - 36 pictures with the kit lens
        stitched better than 6 using the peleng! (sample at
        http://www.nwpropertyphotos.com/)

        I've attempted to attach a copy of a nadir from a 6 shot pano - in the
        event it doesn't attach, the picture depicts the base of the panosaurus
        (a circle) displayed as though there are parallax problems. Imagine a
        nautilus shell put on its side, and shifted 60° about it's "nodal point"
        - there's a bit of a lip from each pano image that contributes to making
        the circle look a bit like a pinwheel... if you can imagine what I'm
        attempting to describe.

        The few thoughts that came to mind:
        - I've incorrectly calibrated the lens/head - I followed the
        instructions precisely, and have come up with the same result on many
        attempts over the last few weeks (17.2 on the far left DSLR scale)
        - Somehow the panosaurus is not rotating precisely and I'm getting
        paralax regardless of calibration
        - There is a flaw in my workflow
        - I'm expecting too much from PTGui
        - I'm expecting too much from my gear

        Any thoughts would be greatly appreciated - I've seen so many fantastic
        panos here and I wish I could share similar great work myself!!!

        I'd be happy to post any files you feel may be salient to this topic.

        I'm also thinking its time to step up to a more substantial pano head -
        any sub-$500US suggestions without locking into a body/lens combo like
        the 360P?

        Thanks in advance,
        Blake


        [Non-text portions of this message have been removed]



        --

        Yahoo! Groups Links
      • Blake Michaelson
        Thank you all for the excellent information! I tore down my system (Canon 350D / Peleng 8mm / Panosaurus - for the next guy who searches for this issue) and
        Message 3 of 8 , Dec 1, 2006
          Thank you all for the excellent information! I tore down my system
          (Canon 350D / Peleng 8mm / Panosaurus - for the next guy who searches
          for this issue) and set it all up once again (I have to admit that the
          link below to eppos.jpg was a nice simplistic approach to checking the
          alignment). I took another 4+1+2 (2 nadir opposed 180°), things
          stitched a little better, but not much different than before.

          However, I did have GREAT success with going into advanced mode of
          PTGui, selecting the Optimizer tab, keeping the Optimizer in simple
          mode, selecting optimize lens Field of View, and selecting Minimize lens
          distortion to "Heavy + lens shift", then ran the optimizer. I ended up
          with an average of 1.03, max of 2.47 and min 0.04 - significantly better
          points, and subsequently significantly better stitched panos! This
          almost completely eliminated the "nautilus" effect with regard to the
          unpatched nadir. I went back and restitched some panos I took prior to
          realigning my setup and they stitched just as precisely as well...

          Thanks for the all the continued assistance - I appreciate it tremendously!

          Blake

          John Houghton wrote:
          >
          > --- In PanoToolsNG@yahoogroups.com
          > <mailto:PanoToolsNG%40yahoogroups.com>, Blake Michaelson
          > <blake.michaelson@...> wrote:
          > >
          > > Imagine a nautilus shell put on its side, and shifted 60° about
          > > it's "nodal point" - there's a bit of a lip from each pano image
          > > that contributes to making the circle look a bit like a pinwheel...
          > > if you can imagine what I'm attempting to describe.
          >
          > This suggests that the lateral positioning of the camera is not
          > correct. The entrance pupil may be located correctly front to back,
          > but not side to side. Whatever instructions you are following, they
          > don't seem to have worked. Try checking the entrance pupil position
          > visually using this simple arrangement:
          > http://homepage.ntlworld.com/j.houghton/eppos.jpg
          > <http://homepage.ntlworld.com/j.houghton/eppos.jpg>
          > Point the eyepiece at a bright light source to illuminate the
          > entrance pupil. Make sure you have the pano head level and use the
          > plumb line to check that the entrance pupil is centered on the axis
          > point.
          >
          > Generally, there is no requirement to accurately level the panorama
          > head and/or the camera to ensure good stitching. Rotating the camera
          > about the no-parallax point is the important thing to get right.
          >
          > John
          >
          >
        • Roger D. Williams
          Blake, I am so glad you got what you needed. As a moderator of the list I must say it gives the very greatest satisfaction to think that we have such
          Message 4 of 8 , Dec 1, 2006
            Blake, I am so glad you got what you needed. As a moderator of the
            list I must say it gives the very greatest satisfaction to think
            that we have such knowledgeable and helpful people in the group.
            I am only a few years ahead of you, and still groping around near
            the bottom of the learning curve but I would still be trying to
            warp images in PaintShop pro if it weren't for this list!

            Roger W.

            On Fri, 01 Dec 2006 17:07:07 +0900, Blake Michaelson
            <blake.michaelson@...> wrote:

            > Thank you all for the excellent information! I tore down my system
            > (Canon 350D / Peleng 8mm / Panosaurus - for the next guy who searches
            > for this issue) and set it all up once again (I have to admit that the
            > link below to eppos.jpg was a nice simplistic approach to checking the
            > alignment). I took another 4+1+2 (2 nadir opposed 180°), things
            > stitched a little better, but not much different than before.
            >
            > However, I did have GREAT success with going into advanced mode of
            > PTGui, selecting the Optimizer tab, keeping the Optimizer in simple
            > mode, selecting optimize lens Field of View, and selecting Minimize lens
            > distortion to "Heavy + lens shift", then ran the optimizer. I ended up
            > with an average of 1.03, max of 2.47 and min 0.04 - significantly better
            > points, and subsequently significantly better stitched panos! This
            > almost completely eliminated the "nautilus" effect with regard to the
            > unpatched nadir. I went back and restitched some panos I took prior to
            > realigning my setup and they stitched just as precisely as well...
            >
            > Thanks for the all the continued assistance - I appreciate it
            > tremendously!

            --
            Work: www.adex-japan.com
            Play: www.usefilm.com/member/roger
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