Couple of quick comments...
First, the no-parallax point about which we rotate a camera lens when
shooting panoramas should properly be referred to as the "entrance
pupil", rather than nodal point. The confusion is understandable.
There are two (front and rear) nodal points within a lens system, and
one of them is even used for the rotation alignment of a swing lens
panoramic camera,. But the term "entrance pupil" is what we should be
using to describe the no-parallax point of a lens for properly
shooting a sequence of images for stitching together as a panorama.
(There is still lots of confusion about this, since the term "nodal
point" was improperly described back at the beginning of QTVR in
Secondly, if you are going to shoot wide angle images for stitching
with a video camera, it is wise to also align the pan axis of the
camera/lens with the entrance pupil of that lens. However, the longer
the focal length of the lens, and/or the greater the distance (of the
nearest subject) from the lens, the less critical this entrance pupil
alignment is for stitching. Stitching applications such as PanoTools
and PTGUI have gotten fairly good at compensating for minor
misalignments in many instances.
However, consider that "video VR" does not necessarily require
stiching, in a number of instances. One example is the use of one-
shot parabolic mirror optics, such as EyeSee360's GoPano. Every frame
shot already comprises a complete 360-degree view.
Furthermore, I have seen traditional video movies used on web sites
that very much had the look and feel of an interactive VR panorama,
but were simply a wide angle video recording done on a fluid video
head tripod. The result looked very much like an auto-panning VR
panoramic movie. In one instance, the viewer could even click on the
movie window to drag left or right. The result was that the video
scrolled forward or backward, essentially increasing the forward speed
or reversing the pan direction.
With a setup like this, entrance pupil alignment is irrelevant,
because there's no stitching involved -- just an old-fashioned video
stream (that happens to be a slowly panning camera movement).
Sometimes, it's good to take a step back and look again at what we're
trying to do. On occasion, one might find that it's better to go with
a different, existing technology than it is to spend endless hours and
energies trying to make a proverbial round peg fit into a square
hole. Figure out what it is that you want (or need) to do -- your
desired end result -- before choosing the tool(s) that will help you
best create it.
Author, Virtual Reality Photography
[Non-text portions of this message have been removed]