proj-imim:
Re: Some questions
Ben Kreunen 2001-May-02 02:50:05
>1. With my old camera setup (Sigma 8mm AF EX, self made pano head,
>portrait mode) i came to an average FOV of 183.5 degree which is quite
>reasonable for this lense. ..... With my new setup (new tripod head,
>Manfrotto QuickTimeVR) the camera is set to portrait mode and I cannot use
>my old starting values......The values for a,b,c are also a=negative,
>b=positive, c=negativ, but much smaller (down under 0.0) but the value for
>FOV is reduced to 173-175. Has someone made the same experiences and can
>give me an explanation?
If you have a lot of vertical lines in your test panorama then use the t1
option very liberally to specify a large number of vertical lines in your
pano. Use control points within the same image, AND between pairs of images
for the same lines. This is very helpful in determining good values for
a,b,c.
I tried one calibration test using only the t1 option for all control
points to stitch a panorama, optimising ALL variables except for y0. The
resulting panorama was not stitched as well as one using just a large
number of control points, BUT the resulting values of v,a,b,c did produce
better results when used normally in subsequent panoramas. It was an
interesting trial but in practise I'd recommend mixing normal control
points with lots of vertical lines using the t1 option.
The values for a,b,c for my Sigma lens (MF) are also around -0.2,0.3,-0.2
respectively. FOV depends on how I decide to crop my scanned images. Being
a circular image it should make no difference whether it's shot in portriat
or landscape orientation.
Slight variations in positioning the camera at it's nodal point can cause
variations in "calibrated" values and this would be the first thing I'd
check being a new setup. My first 20 or so panoramas all looked fine but I
didn't have a proper tripod setup at the time. As soon as I correctly
aligned the camera my values for a,b,c changed.
>2. During scanning i set one image optimization on one image and keep this
>adjustments on the other two images. In theory this would mean that all
>three images are of the same brightness and color. After stitching i
>always have a lot of brightness and color mismatch in my resulting PSD
>File. Have you got the same experiences? I have uploaded a typical series
>of images on
><http://www.360visits.de/panotools.htm>www.360visits.de/panotools.htm i
>would be interested in what way your first stitch looks like.
Lens flare will cause variations in brightness and colour between images.
This is why I manually stitch my images so that I can manually adjust each
image to match.
Cheers
Ben
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