Re: [PanoToolsNG] Re: Nodal Point trouble
- Am 08.11.2010 00:04, schrieb michael crane:
>> > - Allow for optimization of a, b and c lens correction parameters.-> http://wiki.panotools.org/Lens_correction_model
> is there a list somewhere of what "a", "b", "c" etc parameters are ?
I've used with a Manfrotto 303SPH for 3 years.
I've calibrated the head 3 times since I've had it for (once for a new lens).
Results for panning around the horizon are amazing alignment apart from a small 2.7 degree rotation on all the shots. This is easy to fix in PTGui or Hugin.
However stitching near the nadir usually has problems. I think I know why, but it's hard to calibrate the head for and fix.
I'm interested in any suggestions to solve this problem.
Photos of the head for those who aren't familiar:
The camera sometimes slides on the mounting plate. This means it droops mid-shoot. All I can think of is to tighten the retaining screw as much as I have the courage to.
The second problem is also with the mounting plate. Each time I shoot a pano I attached the plate to the camera. How do can this be done consistently? How to measure that it is perfectly at a right angle (90 deg) to the axis of the lens?
When fitting the camera plate to the head, how to slide it to exactly the right position so that the lens axis is centred on the rail and parallel to the rail?
A technique I try is setting the head to point vertically down at the nadir, and centering the centre focus point on the centre bolt of the head rotator. However, this doesn't prevent a combination of an offset AND not parallel alignment. I think this is the cause of the alignment problem.
I am sure the other 2 rail settings are perfect to obtain the no parallax point. I calibrated specifically for 60 degree rotations, as for wide lenses, the NPP is different for different increments.
I have calibrated the lens distortion carefully and load the settings into my project each time. Anyway these are perfect for cylindical panos, so I know they are correct.
---In PanoToolsNG@yahoogroups.com, <email@example.com> wrote:Hello everyone....
I'm still struggling with the calibration of my manfrotto 303SPH head. I shot an exterior of a house and got good results when stitching but as I got in the interior in more narrow spaces I'm still getting a few (not terrible) misalignments specially visible on floor or door lines. In reality it's only a few little mistakes but I'd like to reduce them as much as possible.
Out door shots were taken with a 35mm (full frame) lens while interiors with fisheye 10.5mm (DX!!). I'd like to try to shoot also interiors with my 35mm but I'm afraid of misalignments and depth of field with close objects.
I've used this method to find the nodal point but I find it a bit "approximate" http://dgrin.smugmug.com/gallery/2114189
is there a better, precise way? I know, this must be a topic you've discussed a million times but I beg for patience. :-)