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Technical question on PT coordinate system

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  • Thomas
    I am implementing a new fast stitcher for array cameras, which must be able to use some PT script parameters as saved by Hugin and PTGui, namely camera
    Message 1 of 5 , Feb 16, 2013
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      I am implementing a new fast stitcher for array cameras, which must be able to use some PT script parameters as saved by Hugin and PTGui, namely camera alignments and lens corrections. I have some questions about the panosphere coordinate system used in those stitchers .

      Please refer to the drawing on the PT Wiki page "stitching a photo-mosaic" [here]

      1] do all PT family stitchers use the same coordinate system as original PanoTools?

      2] is it really left-handed, as implied by the drawing?

      3] is the zero yaw, zero pitch point really (0,0,1)?

      4] is the panosphere radius the unit of trX, trY, trZ ?

      Thanks, Tom
    • Erik Krause
      ... As for Yaw, Roll and Pitch: Yes, as far as I know. The TrX, TrY, TrZ mosaic coordinate model is unique to hugin/nona. PTGui uses a different model with 5
      Message 2 of 5 , Feb 17, 2013
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        Am 16.02.2013 15:54, schrieb Thomas:
        > 1] do all PT family stitchers use the same coordinate system as original
        > PanoTools?

        As for Yaw, Roll and Pitch: Yes, as far as I know. The TrX, TrY, TrZ
        mosaic coordinate model is unique to hugin/nona. PTGui uses a different
        model with 5 coordinates: VPx, VPy, VPz, VPpan and VPtilt. They are not
        documented (AFAIK) but Helmut Dersch found them out for himself and
        implemented them in PTStitcherNG.

        Furthermore PTGui uses PTStitcher o-line C-coordinates while hugin/nona
        use S-coordinates. That means hugin coordinates are relative to the
        complete source image while PTGui coordinates are relative to the
        cropped image specified by the C-coodinates (the crop rectangle/circle).
        See
        http://wiki.panotools.org/PTStitcher#o-line_options for details

        --
        Erik Krause
        http://www.erik-krause.de
      • Jim Watters
        ... From Helmut: PTGui uses a 2-axis pan/tilt + 3-d translation, in that order http://tech.groups.yahoo.com/group/PanoToolsNG/message/39331 Dev Ghosh who
        Message 3 of 5 , Feb 17, 2013
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          On 2013-02-17 6:47 AM, Erik Krause wrote:
          > Am 16.02.2013 15:54, schrieb Thomas:
          >> 1] do all PT family stitchers use the same coordinate system as original
          >> PanoTools?
          > As for Yaw, Roll and Pitch: Yes, as far as I know. The TrX, TrY, TrZ
          > mosaic coordinate model is unique to hugin/nona. PTGui uses a different
          > model with 5 coordinates: VPx, VPy, VPz, VPpan and VPtilt. They are not
          > documented (AFAIK) but Helmut Dersch found them out for himself and
          > implemented them in PTStitcherNG.
          From Helmut: "PTGui uses a 2-axis pan/tilt + 3-d translation, in that order"
          http://tech.groups.yahoo.com/group/PanoToolsNG/message/39331

          Dev Ghosh who originally worked on the mosic mode for Hugin during a GSoC, but
          never got finished, has just posted on the hugin-ptx list, "mosaic mode with
          intuitive warp parameters", that he is implementing his original method to
          create orthogonal views.



          >
          > Furthermore PTGui uses PTStitcher o-line C-coordinates while hugin/nona
          > use S-coordinates. That means hugin coordinates are relative to the
          > complete source image while PTGui coordinates are relative to the
          > cropped image specified by the C-coodinates (the crop rectangle/circle).
          > See
          > http://wiki.panotools.org/PTStitcher#o-line_options for details
          Yes the GUIs of PTGui and Hugin use different cropping models.
          http://tech.groups.yahoo.com/group/PanoToolsNG/message/6212
          PTStitcher definitely understands both.

          --
          Jim Watters
          http://photocreations.ca
        • Thomas
          Thank you Jim and Erik. The references on PTStitcher are helpful. I am having a devil of a time figuring out how to apply PTGui y,p,r to a panosphere having a
          Message 4 of 5 , Feb 17, 2013
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            Thank you Jim and Erik.

            The references on PTStitcher are helpful.

            I am having a devil of a time figuring out how to apply PTGui y,p,r to a panosphere having a right-handed coordinate system (meaning my X axis points left) Like PT, view is centered on (0,0,1) at y=p=r=0. Inverting the X axis in the rotation matrix seems to give correct alignments, however my projection mapping fns then fail.

            I need to invert the hand again without losing the alignment, this is surely possible but I can't find the right way to do it.

            Alternatively I could revert to left-handed coords, which Panini used for a long time, but I feel a bit stubborn since it took some effort to convert everything to right-handed.

            -- Tom

            --- In PanoToolsNG@yahoogroups.com, Jim Watters <jwatters@...> wrote:
            >
            > On 2013-02-17 6:47 AM, Erik Krause wrote:
            > > Am 16.02.2013 15:54, schrieb Thomas:
            > >> 1] do all PT family stitchers use the same coordinate system as original
            > >> PanoTools?
            > > As for Yaw, Roll and Pitch: Yes, as far as I know. The TrX, TrY, TrZ
            > > mosaic coordinate model is unique to hugin/nona. PTGui uses a different
            > > model with 5 coordinates: VPx, VPy, VPz, VPpan and VPtilt. They are not
            > > documented (AFAIK) but Helmut Dersch found them out for himself and
            > > implemented them in PTStitcherNG.
            > From Helmut: "PTGui uses a 2-axis pan/tilt + 3-d translation, in that order"
            > http://tech.groups.yahoo.com/group/PanoToolsNG/message/39331
            >
            > Dev Ghosh who originally worked on the mosic mode for Hugin during a GSoC, but
            > never got finished, has just posted on the hugin-ptx list, "mosaic mode with
            > intuitive warp parameters", that he is implementing his original method to
            > create orthogonal views.
            >
            >
            >
            > >
            > > Furthermore PTGui uses PTStitcher o-line C-coordinates while hugin/nona
            > > use S-coordinates. That means hugin coordinates are relative to the
            > > complete source image while PTGui coordinates are relative to the
            > > cropped image specified by the C-coodinates (the crop rectangle/circle).
            > > See
            > > http://wiki.panotools.org/PTStitcher#o-line_options for details
            > Yes the GUIs of PTGui and Hugin use different cropping models.
            > http://tech.groups.yahoo.com/group/PanoToolsNG/message/6212
            > PTStitcher definitely understands both.
            >
            > --
            > Jim Watters
            > http://photocreations.ca
            >
          • Erik Krause
            ... Read on Euler angles: http://en.wikipedia.org/wiki/Euler_angles (This is the exact point where my knowledge ends ;-) -- Erik Krause
            Message 5 of 5 , Feb 17, 2013
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              Am 17.02.2013 21:07, schrieb Thomas:
              > I need to invert the hand again without losing the alignment, this is
              > surely possible but I can't find the right way to do it.

              Read on Euler angles: http://en.wikipedia.org/wiki/Euler_angles

              (This is the exact point where my knowledge ends ;-)

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