Parameters to correct perspective error?

  • Hi forum,

    I’ve made an elevated pano with a handmade pole, and after stitching and retouching with PS
    some strong perspective errors, mainly because of bad quality pole, I found out that the horizon
    sea line is curved when seen at krpano viewer (the retouched equirectangular looks ok) …

    Is there any krpano settings, like pitch values or something like that, that I can
    include in XML code in order to correct this distortion when playing the pano?

    Viewer’s image of this area of the pano:

  • Hi forum,

    I’ve made an elevated pano with a handmade pole, and after stitching and retouching with PS
    some strong perspective errors, mainly because of bad quality pole, I found out that the horizon
    sea line is curved when seen at krpano viewer (the retouched equirectangular looks ok) …

    Is there any krpano settings, like pitch values or something like that, that I can
    include in XML code in order to correct this distortion when playing the pano?

    Viewer’s image of this area of the pano:

    This is because you stitched your image wrong and your horizont is not on the centre line of your equirectangular image.
    It may be because you added the nadir in a wrong way.
    It can easy be adjusted in photoshop with some stretching and then you have to edit the nadir again.

    Hans

  • I thought that it could be easier to correct with viewer parameters,
    I’ve tried with that “prealign” attribute, that gave me different start positions
    and view angles, but the distortion persists, because as Hans said the horizon
    was clearly above the centre line of my equirectangular.

    I ‘ve stretched the image in PS with transform tool to take the horizon back
    to the centre, and being the distortion not that big I didn’t even had to edit the nadir.

    Thanks for your answers gentlemen.

  • Thank you Leszek, according to attribute's description "voffset" seems to be what
    I was looking for originally.
    I've tried out some values but horizon keeps the same curved, I just noticed kind of
    waving or bouncing when playing along the pano ... anyway I've already solven the
    problem taking horizon to center with PS as they told me.
    I take note of "voffset" and see if I can make it work for me in the future,
    I fear I will need it again as long as I don't change this crappy pole.

    Raul.

  • Setting voffset is a good way to correct panorama if it has straight horizon but not lying in the middle of the image. If it is a wavy it need to be straighten. It's almost not possible to make straight panorama with a pole,and it usually have to be straighten in stitcher. If you send me your panorama I'll try to straight it for you.

  • Some time ago Klaus added voffset param of image tag and this is exactly what you need. I'm not sure if it woks with all panorama fomats. It certainly works with equirectangular format.

    From what I can see this is only supposed to work with partial spherical panoramas. Not Equirectangular. And of course that makes sense. You can not change the center without it will have effect on zenith and nadir.

    Hans

  • Hi,

    the voffset setting will work on all spherical and cylindrical panos, also on 360x180 panos but there it doesn't make much sense (but it can be funny to play with the settings )

    note - the in 1.0.8.14 version of the options plugin you can play with/change the voffset setting interactively (and also the other hfov/vfov image settings),

    here a screen shot:

    e.g. try it on that partial pano here:
    https://krpano.com/krpano.html?pa…sseum_vorne.xml

    best regards,
    Klaus

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