Stitching images taken with vertical shift

[Rene]

Hi,
Can PTgui be configured to stitch images that have been taken with the
camera rotating in the usual way but with a tilt/shift lens shifted
vertically in order to eliminate unwanted foreground? This brings the
horizon below the centre line of the final picture while still
retaining the full image resolution.

The setup that I am using is Canon 5DII with Canon 24 f3.5 TS LII
lens, mounted on a pano head in portrait mode, the camera & lens
aligned at the 'nodal' point and with the lens shifted vertically by
10mm.
I have experimented with setting a vertical shift in the lens settings
menu, but so far without a lot of success in obtaining a reasonable
pano fit [perhaps these vertical & horizontal shift settings are more
intended for correcting lens misalignment than for these larger
shifts].

Surprisingly, Photoshop does a reasonable job in photomerge
(cylindrical) but with the usual drawbacks of no control over the few
little ghosting & misalignments nor the ability to merge HDR images.
It would be much preferable to find a way of doing this in PTgui.

Is anyone able to suggest an approach to specifying settings that may
work in this case?
Thank you in advance for your assistance.
Rene

[John Houghton]

PTGui should cope with the vertical shift (but not lens tilt).
Initializing the vertical shift parameter (e) to 1560 should be about
right. After aligning the images using this fixed amount, you can
then include both d & e parameters in the optimization along with the
other lens parameters a,b, & c, in order to fine tune the alignment.

John

[Simon Nobes]

I have seen one or two references to tilt/shift lenses being used in
panoramas - and am having difficulty imagining what effect it will
have on the final result. Any chance you could post a link to the
completed picture when (and if!) you manage to stitch it together?

Many thanks

Simon

On May 4, 12:56 pm, Rene <renevogelz...@gmail.com> wrote:

[PTGui Support]

When stitched succesfully the panorama will look exactly like the same
scene taken with a regular lens. PTGui reprojects images to fit into the
360 degree sphere and the reprojection undoes the shifting of the image
center.

The only difference is sharpness: when you shift the lens the focus
plane (i.e. the plane of objects that appear sharp) stays the same,
while with a regular panorama the focus plane changes as you rotate the
camera (effectively approximating a focus sphere).

Also when shifting the lens you are using more of the outer edges where
the image quality of the lens degrades.

Tilting the lens only affects the focus plane, which is no longer
perpendicular to the viewing direction.

For more information see 2.19:
http://www.ptgui.com/support.html#2_19

Joost

On 5-5-2011 11:54, Simon Nobes wrote:
> I have seen one or two references to tilt/shift lenses being used in
> panoramas - and am having difficulty imagining what effect it will
> have on the final result. Any chance you could post a link to the
> completed picture when (and if!) you manage to stitch it together?
>
> Many thanks
>
> Simon
>
> On May 4, 12:56 pm, Rene<renevogelz...@gmail.com> wrote:
>> Hi,
>> Can PTgui be configured to stitch images that have been taken with the
>> camera rotating in the usual way but with a tilt/shift lens shifted
>> vertically in order to eliminate unwanted foreground? This brings the
>> horizon below the centre line of the final picture while still
>> retaining the full image resolution.
>>
>> The setup that I am using is Canon 5DII with Canon 24 f3.5 TS LII

>> lens, mounted on a pano head in portrait mode, the camera& lens

>> aligned at the 'nodal' point and with the lens shifted vertically by
>> 10mm.
>> I have experimented with setting a vertical shift in the lens settings
>> menu, but so far without a lot of success in obtaining a reasonable

>> pano fit [perhaps these vertical& horizontal shift settings are more

>> intended for correcting lens misalignment than for these larger
>> shifts].
>>
>> Surprisingly, Photoshop does a reasonable job in photomerge
>> (cylindrical) but with the usual drawbacks of no control over the few

>> little ghosting& misalignments nor the ability to merge HDR images.

[Erik Krause]

Am 05.05.2011 11:54, schrieb Simon Nobes:
> I have seen one or two references to tilt/shift lenses being used in
> panoramas - and am having difficulty imagining what effect it will
> have on the final result.

A shift lens is a normal lens with a relatively large image circle. The
shift mechanism moves the smaller crop inside this image circle. Hence a
stitched panorama taken with the camera level and the lens shifted such
that the horizon is at the bottom of the frame will just look like one
taken with the same lens (unshifted) on a sensor with double height and
then cut away the bottom half.

But as Joost wrote there is little point using a shift lens for
panoramas. You can use a cheaper and possibly better lens and simply
shoot tilted up.

--
Erik Krause
http://www.erik-krause.de