About the NODAL POINT! Panorama Photography.

[Inkanyezi]

Because I use a TS lens, it's not necessary to know the nodal point.

Panning, as we mostly use the term, means to swing the camera around an axis, to change the angle, in which we point the optical axis.

When you use the shift function to cover a larger angle, you are effectively using the larger image circle of the shift lens, merging two images into one, to create an image as if taken with a larger sensor size. When doing this in a way that returns the lens to its original position before taking the second shot, by shifting the camera an equal amount in the opposite direction, you will address parallax issues within the scene - one image lens shifted left, camera right, and the other lens shifted right and camera left.

The result, when using a shift lens with a miniature format camera is the same as using the same lens with a medium format camera, cropping top and bottom to leave a 24 mm strip from the centre. You achieve a rectilinear wide angle image; call it panorama if you wish, but the issue that above described methods will address is parallax errors when panning, sweeping an angle by turning the panorama head.

When the axis around which we turn the camera intersects the entrance pupil of the lens, no parallax errors will occur. There will of course be other errors that we address with software. Either, the image will have to be corrected from the rectilinear imaging of the lens into the cylindrical shape of the panorama, or, we could snip out a part of the panorama and correct it to a rectilinear image. Panorama stitchers may also stretch and shrink to cope with lens distortions. Another way to cope with distortions is to merge rather narrow strips from many more images taken with small angular difference.

[Kodiak]

Thank you for now choosing to reveal that information.

Hi William,

Is the NOW a problem to you?

I did design some graphics about this topic… but, you know me (maybe!)
I am quite exhaustive, accurate, and extremely thorough at times. The
graphs I produced were too elaborate for the context of a forum and I was
authorized to use these much simpler and quite adequate ones some years
ago by the cool dude himself.

As I explained before, I was very worried to be too obscure and complicated!
While preparing this thread, I wanted to do the best possible contribution. If
I overlooked to reveal this info in the first post and you see it as wrong then
I am very sorry for the omission. Normally, I am very picky when it come to
mine or others © and I think I do not need to steal others property.

Sorry again.

[Manfred M]

I think one other fairly important aspect has been missed / misunderstood and that is parallax is mostly an issue for subject matter that is "close" to the camera. The reason I put "close: in quotes is that the focal length being used (and the camera's crop factor) will be the determining factor.

The further you get away, the less the impact of not rotating the camera around the nodal point / entrance pupil has on the image, and hence the subsequent distortion in the image. Objects at or near the "infinity" setting of your lens will look fine (Note: Stopping down to increase DoF to get more of the scene in focus; but the close up material will be distorted) .

So, if you stand on a bridge and lean over the railing (or stand near the edge of a cliff) and shoot a landscape pano; it will likely look fine, so long as you hold your camera reasonably level. I've done lots of these shots hand held. But if you step back and want to capture the bridge railing; your camera had better be set up to rotate around the len's nodal point if you want this to come out distortion free.

[george013]

A friend of mine said to me to experiment with a panorama on the street with streetstones in the forground.
That should be very sensitive for faults. I didn't do it yet.

George

[Kodiak]

A friend of mine said to me to experiment with a panorama on the street with streetstones in the foreground. That should be very sensitive for faults. I didn't do it yet.George

If you're prepared properly, there should be no difficulty… just look at the
floor of the church, above.

[george013]

If you're prepared properly, there should be no difficulty… just look at the
floor of the church, above.

I believe you, but it is an easy subject to show the faults one makes. If you have streetstones in front of the door, two-dimensonal lines.

George

[inkista]

Nadir shots are always problematic with 360x180 panos, because you have to get the tripod out of the way, and shutter speeds may not allow for that if you're indoors. OTOH, there are tricks and ways and means around this. I tend to default to viewpoint correction for the patch, because I have PTGui. And I've always got an eye out for a featureless "floor". If you select your vantage point correctly, even a simple patch correction in photoshop can work. I took the following pano handheld (four shots, 90-degree intervals with the Sigma 8mm circular fisheye on my Canon XT)--there is some leeway with parallax error depending on the stitcher you're working with. No extra zenith or nadir shots were needed, and simple patching on cube faces worked just fine.


Interactive view.

However, for something like this from-inside-the-doorway pano, I really needed the tripod, my little Nodal Ninja to let me rotate the lens around the NPP in pitch as well as yaw for the zenith & nadir shots, and all the tricks. I was just too stupid to realize I needed HDR coverage, too.


Interactive view.

[Kodiak]

•
Just to extend the fun…

The same church a view up… and down

[Manfred M]

•
Just to extend the fun…

The same church a view up… and down

Nice images; but I'll get dizzy if I stare at them too long.

[inkista]

[Manfred, don't look!]

And this is the difference between making little planets from 360 vs. 360x180s: floor coverage .



The Flexify plugin for Photoshop is an absolute blast for this stuff, since it has some pretty exotic mappings, such as if you want to fold an origami balloon out of your pano to get a cube:



And there's the standby stereographic little planet thing, of course, if you've been shooting outdoors:



Of course, to me, the absolute weirdest remapping you can do is the whole drostified Peirce's quincunx thing for which you need the Gimp and Mathmap:



I've had people respond on messageboards to these with "WTF?!" a lot.

[William W]

. . .Is the NOW a problem to you?

No.

I have no problem with either your opening post nor your response about the illustrations.

I was thanking you for giving credit where credit was due: the word 'now' is simply being accurate:

> If I had wanted to place emphasis on the word 'now' - I would have.

> If I had any 'problem' - I would have written something like:

"I think that it would have been better to credit the illustrations in your OP"


***


More detail if you require -

. . . you know me (maybe!)

I am quite exhaustive, accurate, and extremely thorough at times.

The graphs I produced were too elaborate for the context of a forum and I was
authorized to use these much simpler and quite adequate ones some years
ago by the cool dude himself.

As I explained before, I was very worried to be too obscure and complicated!
While preparing this thread, I wanted to do the best possible contribution. If
I overlooked to reveal this info in the first post and you see it as wrong then
I am very sorry for the omission. Normally, I am very picky when it come to
mine or others © and I think I do not need to steal others property.

Sorry again.

Possible that we have met.

I already understood, before reading this thread, that you are precise, meticulous and exhaustive.

I appreciated your opening post and I thanked you for it with that "like this" option - because your OP is very good, user friendly and useful.

I read your response about the illustrations and I assumed by the words "cool dude" that it was quite OK for you to use the illustrations - and also I appreciated that you went further (because of your precision) and acknowledged your friend in Melbourne.

The fact that you have taken the time to address what you thought was a concern by another member about an oversight of yours, shows that you are meticulous and that you strive for precision.

Stop worrying, there is no need to apologize to me.

WW

[Kodiak]

No. Stop worrying… WW

Cool William, thank you.

[William W]

Good.

[Kodiak]

•

Hey Bill,
Where is Sraylya? Google never heard of it! …me neither.

[William W]

. . . Of course, to me, the absolute weirdest remapping you can do is the whole drostified Peirce's quincunx thing for which you need the Gimp and Mathmap:

A word that I strive to use often and is an ideal for a triple word score in scrabble - I am so glad someone else uses it too.

***

I've had people respond on messageboards to these with "WTF?!" a lot.

I'd argue - "Kathy's Kaleidoscope" - is a better response.

WW

[William W]

Where is Sraylya? Google never heard of it! …me neither.

Google (and also Wikipedia) are hopelessly inadequate.

You need your friend in Melbourne to teach you to speak "Strine"

Pronounced STRAYL- ya. (emphasis of the first syllable)

Specifically I live is SID - NEE (equal emphasis on both syllables)

WW

REF: http://en.wikipedia.org/wiki/Strine

[inkista]

[re: "quincunx"] A word that I strive to use often and is an ideal for a triple word score in scrabble - I am so glad someone else uses it too.

I gotta say, while reading a Preston & Child novel where they ended up using a five-of-diamonds glyph to describe the arrangement of objects, I started muttering, "There's a perfectly good word for that, y'know!"

I'd argue - "Kathy's Kaleidoscope" - is a better response.

I prefer "Girls do math, too!"

I was slow, though, on figuring out that if I rotated things 45-degrees, I could get a Hokusai fractal land-wave with the Quincuncial.mm script:

[William W]

. . . I prefer "Girls do math, too!"

I was slow, though, on figuring out that if I rotated things 45-degrees, I could get a Hokusai fractal land-wave with the Quincuncial.mm script: . . .

Hilarious.

You win this round.

0612 hrs down here and it is bloody cold.
I am rolling on the bedroom floor killing myself laughing
Time to make coffee.
What a great start to my day!

CU all later

Bill

[Kodiak]

Google (and also Wikipedia) are hopelessly inadequate.

You need your friend in Melbourne to teach you to speak "Strine"

Pronounced STRAYL- ya. (emphasis of the first syllable)

Specifically I live is SID - NEE (equal emphasis on both syllables)

WW

REF: http://en.wikipedia.org/wiki/Strine

OK! (equal emphasis on both letters) I gotcha!
This being the funniest lesson I had for a long time! ;-)

[TonyW]

This is just an appreciation of this thread. It has entertained me and taught me many things. For example, I am ashamed to have to say that I had not heard the word "quincunx" before, a word which needs care with its pronunciation. I knew about conformal transformations before, but had not heard of the "quincuncial map". Nor had I seen such cute panoramas.

One small correction though. In the standard pronunciation of "Straylya", the "l" is silent. Similarly with the "d" in "Sidnee".