Re-level or not?

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  1. Re-level or not?

    #1

    Hi
    Should I re-level the tripod for the Nadir patch shot or not......I seem to find conflicting views.
    Also I find in PTGui that Viewpoint correction works better if I tick both the Nadir shots. Does that seem right? In fact, I actually loaded all the images (including Nadir2), ticked VP for the 2 Nadirs and it stitched perfect, then masked and the Nadir looked perfect...........couldn't remember if I re-levelled though between Nadirs, hence the question.
    Thanks
    John

    BTW is there a reason for masking everything but the floor for Nadir2?
    Last edited by Johnytuono; 09-02-2013 at 01:31 PM.
  2. #2
    Users Country Flag
    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,388

    you should not re-level the images taken at NPP. Re-leveling move lens away from NPP.
    You can re-level the nadir shots. With the weight of camera and lens further away from tripod center, the lens axis will be tilted towards center column, even with the strongest tripod.

    Nick



    Fanotec
    We listen. We try harder.
  3. #3

    Quote Originally Posted by Johnytuono View Post
    Should I re-level the tripod for the Nadir patch shot or not......I seem to find conflicting views.
    When you are making use of viewpoint correction, it's not necessary to re-level the tripod. It's a complete waste of time. Re-levelling is only needed in order to preserve perspectives when merging nadir images before stitching (e.g. when using a stitcher not having viewpoint correction facilities).

    Also I find in PTGui that Viewpoint correction works better if I tick both the Nadir shots. Does that seem right?
    In theory, a nadir shot taken at the NPP by simply rotating the camera downwards on the panohead should not need viewpoint correction. In practice, the NPP is rarely perfectly maintained as the head is moved into the nadir position, so invoking viewpoint correction may well offer a useful fine tuning of the alignment, particularly if the head is poorly set up.

    BTW is there a reason for masking everything but the floor for Nadir2?
    Viewpoint correction only works for features lying within a plane surface (level or sloping). Any parts of the scene located outside of the flat plane will not be corrected to bring them into alignment with the corresponding parts of overlapping images. So items poking up or down from the plane need to be masked out. It's ok to have a 3D object in the central area of the nadir, but take care to keep control points off it and if necessary apply masks to ensure that only one complete view of it makes it through to the blended panorama.

    John
  4. #4
    Users Country Flag
    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,388

    Hi John H,

    I assume Johnytuono refer nadir shots to those taken with nadir adapter at swung out position.

    NIck



    Fanotec
    We listen. We try harder.
  5. #5

    Hi
    Yes I meant with the Nadir adapter swung out and not re-levelling for the 'normal' Nadir shot or any other shots in the 360 rotation.
    Anyway I tried both ways....re-levelling for Nadir2 and without re-levelling for Nadir2...and with these shots I tried the various configurations of VP for Nadir and Nadir2.....end result was perfect for both Nadir2 shots (re-levelled and not) but with VP ticked for both Nadir and Nadir2........but ooops.....forgot to take the Zenith lol.
    Last edited by Johnytuono; 09-03-2013 at 09:18 AM.
  6. #6
    Users Country Flag
    Join Date: Aug 2008
    Location: Netherlands
    Posts: 1,740

    John,

    You only level your first shot. Then go around and do all your shots. After importing to PTGui, you have to fink the "viewpoint correction" in >Optimizer > Advanced only for the Nadir2 shot because it is the only shot not done in NPP.
    BTW,in >optimizer I always use "minimize lens distortion" with "heavy + lens shift".

    Have a look at this: http://ge.tt/7JVt50e/v/1

    https://vimeo.com/65994333

    Your spacer is on it's way and should arrive within around 3 workdays.
    Heinz
    Last edited by hindenhaag; 09-03-2013 at 10:23 AM.
  7. #7

    Thank you for that Heinz.......look forward to receiving it.
    John
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