5D+16-35LII problems

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  1. 5D+16-35LII problems

    #1
    Unhappy

    Hi,

    I chose the NN5 mainly due to the tables of nodal points that NN provide. The one for the Sigma 8mm is spot on perfect. With the 16-35L the supplied figures were out (they don't say which focal length they are for anyway) and using both the methods described here (http://www.johnhpanos.com/epcalib.htm) I found it to be 128mm on the top rail, 10mm more than in the NN table.

    Problem is that I can't get a good stitch using either Autopano or PTGui, they both come up with the same alignment problem in the same place with a very near object alignment with a far object and nothing I can do with the software makes any difference (I know AP very well).

    The same panorama in exactly the same spot is perfect using the fisheye. I've spent 7 hours already trying different configurations, etc but not getting anywhere. I had assumed that with the correct nodal point having very near/far objects would be irrelevant, it's why I bought the NN5, Can anyone help me?
  2. #2
    Users Country Flag
    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,427

    there are 2 sources of stitching errors. one is incorrect NPP, the other is wrong lens parameter. If you follow John's tutorial, you should trust your NPP. Have you try to add some manual control points to force the images to stitch? Can you provide some sample images for others to inspect parallax or try stitching?

    here is a good free online storage (5GB free account) that will allow you to backup files and share them
    https://www.sugarsync.com/referral?rf=d3jzjvp4emhag



    Nick
    Last edited by nick fan; 04-04-2011 at 10:04 AM.



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

    Tried with manual points, no luck. Here are the pics if anyone wants a go, the problem is with the kitchen cupboards and the beam above (please excuse the mess!).

    www.studio-beni.net/pano.zip

    If anyone has some figures that I should be using for a 5D with a 16-35LII @ 16mm instead which will give me better results I'd be happy to try and report back.
  4. #4

    The images stitched without any trouble using PTGui (control points automatically generated + a few manually placed ones to improve the spread). Project file and stitched output is at: http://www.johnhpanos.com/pano-beni.zip.

    John
  5. #5

    That is indeed perfect, I'm not an expert with PTGui but I have to work out why the image needs manual control points, does that not usually point to a nodal point error or is it just a difficult image for software to deal with automatically?
  6. #6

    I've spent a few hours now trying to get it to work in Autopano Pro. Looks as bad as when I was trying to do interiors without a nodal point solution. Very disheartening as this is what I bought the NN5 for, I shouldn't have to buy new software (I'm using PTGui as trial) to get a stitch when I'm stitching with nodal point rotation. Not sure where I go from here...
  7. #7

    Ben, It often happens that the distribution of auto generated control points is less than ideal. For the images to align well all along the overlap areas, you need control points spread all along those areas, so that the optimizer can calculate the distortion correction parameters a,b, and c effectively. Frequently the control points generator neglects the corners of the images, so it's advisable to make good any deficiencies by manually assigning a few points. Once the lens parameters have been evaluated reasonably well, these can be used in subsequent projects, thus relieving the optimizer of having to calculate them, in which case the ideal spread of points is no longer necessary. In fact, with good lens parameters applied either manually or with a template, you can manage with only two points per overlap, though a few more will usually be helpful. (Any saved project file can be used as a template for presetting image and lens parameters).

    You might like to refer to this short description of how PTGui's optimization process works: http://wiki.panotools.org/Optimization.

    John
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