Need help on stitching panoramas and perspective

[PhotoByTrace]

Hi all,
I have the photo below of the jetty and bay which is a stitched panorama. It was stitched from 6 portrait oriented photos taken at a focal length of 22mm. I feel as if the jetty has bulged somewhat in the stitching process. I tried both photoshop and PTGui. I'm wondering if this needed to be shot differently (next time) and/or dealt with in post-processing.

So in terms of how it was shot, I'm wondering if this is due to me not having the parallax point precise enough (I should have been at 24mm) for where the camera was set on the rail. Or whether I was trying this from a poor vantage point for perspective. Or whether I should have shot this normal (35-50mm) rather than wide angle?

As for post-processing, I've only stitched reasonably straight-forward landscapes before, and typically use auto or cylindrical stitching. Should I be using a different stitching pattern? Are there other tools in PTGui that can help me correct this during the stitch? Any good tutorials for PTGui around slightly more advanced topics?

Or should I be trying to deal with this post stitching? I'm completely unfamiliar with the warping and other tools in Photoshop, so I'm not sure if this can be dealt with post-stitching? Again, wondering if anyone can direct me to any good tutorials that might assist me learn more.

Thanks in Advance.

[PhotoByTrace]

ps... this wasn't on my list of things to learn for 2015 but life has ways of providing challenges that don't fit on my to-do list

[pnodrog]

For the few panoramas I do I have used mostly from 50 to 80mm focal length in portrait. It takes a few more shots but it seems to give a better result.

Very nice lighting and clouds.

[Manfred M]

Trace - This is a setup / shooting issue, not a PP one.

The issue that you are seeing is that your camera was not rotated around the lenses entrance pupil, with part of the scene in the foreground. That is why you are getting the "bowing" effect. I'm not sure what your setup looks like, but this is more or less what I use. Getting rid of the foreground would also solve your problem.




You might find the following link of use: http://www.johnhpanos.com/epcalib.htm . It covers a lot of the material.

If you get the entrance pupil correct, and rotate around it, then you won't see the bowing. Example here is one of my panos; the railing is straight, so I can tell I got the entrance pupil distance right.





I hope that this helps.

[dubaiphil]

You have a very wide effective field of view - I'd try different stitching patterns in PTGui

Some will reduce the bulging effect, but stretch your vertical edges - the advantage for architecture is that your straight lines remain straight

[george013]

It's mentioned before, but you could try Microsoft Ice. I had bad results with the other programs when I started playing with panos. Nodal point faults are mostly in nearby subjects, thats what I heard and experienced. If you have no nearby straight lines, even handheld is good possible.A pano of 9 photo's handheld, Microsoft Ice.

George

[PhotoByTrace]

Trace - This is a setup / shooting issue, not a PP one.

The issue that you are seeing is that your camera was not rotated around the lenses entrance pupil, with part of the scene in the foreground. That is why you are getting the "bowing" effect. I'm not sure what your setup looks like, but this is more or less what I use. Getting rid of the foreground would also solve your problem.

You might find the following link of use: http://www.johnhpanos.com/epcalib.htm . It covers a lot of the material.

If you get the entrance pupil correct, and rotate around it, then you won't see the bowing. Example here is one of my panos; the railing is straight, so I can tell I got the entrance pupil distance right.

I hope that this helps.

Thanks Manfred, I feared it may have been that I wasn't rotating at the no-parallax point. My only experience with that in the past, before I got my rail, was that straight lines didn't meet up as they were at different angles; so the bowing/bulging was what I was unsure of.
My setup is much like yours. I use the RRS panning clamp and nodal slide. My measurements for the 16-35 Nikkor are 150mm at 16; 140mm at 24; 150mm at 35mm. I guess I may not have had it precisely at 140mm in the dark plus that I wasn't quite at 24mm either.... *sigh*. Need to take more care

[PhotoByTrace]

For the few panoramas I do I have used mostly from 50 to 80mm focal length in portrait. It takes a few more shots but it seems to give a better result.

Very nice lighting and clouds.

Thanks Paul. I also like to shoot more distant panos with my tele lens, but our humidity is such at the moment that the tele really emphasizes the haze and I also find it more tricky to keep all elements in focus. Add to that bracketing for blending and I went for (what was supposed to be) the "easier" wider option on this occasion.

You have a very wide effective field of view - I'd try different stitching patterns in PTGui

Some will reduce the bulging effect, but stretch your vertical edges - the advantage for architecture is that your straight lines remain straight

Thanks Phil, I'll play some more and see if I can recover it sufficiently.

It's mentioned before, but you could try Microsoft Ice. I had bad results with the other programs when I started playing with panos. Nodal point faults are mostly in nearby subjects, thats what I heard and experienced. If you have no nearby straight lines, even handheld is good possible.A pano of 9 photo's handheld, Microsoft Ice.

Thanks George, I should look at that software at some point. But at the moment I don't feel I understand all of PTGui's features well enough to know it's limitations to know whether I "need" another software. I'll certainly do some more reading on them both soon.

[dennybeall]

Interesting, I need to think on this a bit since I'd always thought that the pivot point was the sensor in the camera (as marked on the camera body), not somewhere on the lens.
Can't argue with success though and GrumpyDiver's pano looks good.

[Mark von Kanel]

Hi Trace.

Manfred has already said how to get it better in camera, try this tutorial to correct your existing image, make sure you watch it all because when it starts it may not seem relevant, but i think it will give you the process to correct in PS

http://phlearn.com/secrets-to-an-amazing-bokeh-panorama

[PhotoByTrace]

Thanks Mark, that tutorial did help. I also looked at a couple on perspective warp and puppet warp. They helped me start to get in and play to see what was possible.
In the end I used some distortion control and puppet warp. Still not really how it should be, but I'm happier with it. Next time I'll get it right while kneeling on the sand, much more pleasant than in front of the computer. Though having said that, right now in the aircon is certainly more pleasant than the 91% humidity we had for sunrise this morning.

[Stagecoach]

Well sorted Trace.

Kneeling on the sand ? Get yourself a fold-up fisherman's stool and do it in comfort and style if there's no convenient driftwood to sit on

[PhotoByTrace]

LOL Grahame! That would just be more to carry in
Although admittedly this particular location wasn't much of a hike from the carpark and was pretty civilized. And I barely got wet

[Manfred M]

Your shooting conditions look a lot nicer that mine. I was doing some pano test shots this morning, in the ice and snow...

[PhotoByTrace]

But look at all that pretty white Such a pretty scene for a daytime cityscape.
I'm envious right now as it has been about 10 years since I've played in snow... I went to visit friends in Finland for Christmas about five years ago and they had their first "black" christmas in years. I couldn't believe I'd traveled all that way and missed out on seeing snow, cross-country skiing and snow showers between saunas. C'est la vie.
Though I recognise playing in it on holidays and living and working in it on a daily basis are quite different animals .

[chauncey]

L.Paul has the right idea, if ya want a successful panorama, use a longer glass (less lens distortion)
and shoot more pictures.The "nodal aspect tripod head" has never concerned me. If it was
"rocket science", I couldn't do it. When I use a tripod, it's cause I'm old and tired.

Panoramas are not limited to epic scenes as in this "above the clouds", you can combine multiple single
birds as they traverse a pond or, to make a single subject quite large as in the dove which is 30" high.

[Manfred M]

But look at all that pretty white Such a pretty scene for a daytime cityscape.
I'm envious right now as it has been about 10 years since I've played in snow... I went to visit friends in Finland for Christmas about five years ago and they had their first "black" christmas in years. I couldn't believe I'd traveled all that way and missed out on seeing snow, cross-country skiing and snow showers between saunas. C'est la vie.
Though I recognise playing in it on holidays and living and working in it on a daily basis are quite different animals .

Absolutely correct. Playing in it can be fun, but walking in it, driving through it and shovelling it are no fun at all. In the city, after a few days, that nice white colour is replaced by a dirty gray tone from all the passing vehicles; not pretty and no fun either.

The week of -20C to -25C temperatures we went through is no fun either. On the other hand, spring is coming! (Just not soon enough).

[PhotoByTrace]

L.Paul has the right idea, if ya want a successful panorama, use a longer glass (less lens distortion)
and shoot more pictures.The "nodal aspect tripod head" has never concerned me. If it was
"rocket science", I couldn't do it. When I use a tripod, it's cause I'm old and tired.

Panoramas are not limited to epic scenes as in this "above the clouds", you can combine multiple single
birds as they traverse a pond or, to make a single subject quite large as in the dove which is 30" high.

Thanks for your input and for sharing those lovely panos. Your multi-bird pano always catches my eye. It gave me inspiration to try something similar with a dog at agility; though I haven't been happy with the outcome yet.

However, all that said, I disagree that you need to use a long lens for a successful panorama. I believe it depends on how you visualize the scene you are wishing to capture, as you yourself have demonstrated with your examples.

In this case I wanted to capture wide to normal as I didn't wish to compress the background and I wanted to accentuate the length of the jetty while being close and low down to that jetty. While I do quite often do panoramas with both my 50mm and my tele lenses, it completely depends on how I wish to render the scene (and sometimes the gear I have with me) as to what I'll choose to use. The "nodal aspect tripod head" and "rocket science" won't matter if you avoid foregrounds, which I'm guessing from your lovely examples is your preference.

I messed up with this one that I created the thread for, and initially I wasn't sure why. But it turns out it wouldn't have mattered what length I'd been trying to shoot it at, if I'd made the same mistake of not rotating around the no-parallax point with a relatively close foreground, I would have had issues in stitching. I could possibly have shot this with my 50mm from that vantage point, but it would have needed to have been multi-row and concentrating on my focal distance would have been much more critical. My other consideration was the time of day, the more images being taken at dawn, especially multi-rows, the more likely I am to have problems with shifting light.

Since we are giving examples, my own shooting preference leans towards epic landscapes. Hopefully this one demonstrates that longer glass is not necessary for a successful panorama.
This one was 8 images each taken at 16mm.


This one isn't exactly epic but was six handheld at 125mm with no close foreground to show I can do it that way too Though I'll admit I rarely shoot landscapes, pano or otherwise, without my tripod. I love my tripod and to me it is an extension of my camera. If I'm without it and taking landscapes, it usually indicates I'm on my bike and only had space for the camera.


This one was 15 images at 70mm for the local tourism authority. I think it is going on the side of a bus.

[inkista]

Just me, but the bowing has nothing to do with rotating around the no-parallax point (which, btw, is NOT the entrance pupil, and is NOT the nodal point of the lens but that's an argument for another time). If you've introduced parallax error into your member images, what will happen are noticeable "breaks" in edges across the seams, because objects will have "moved" relatively between the member images.

What does cause the bulging is the remapping that has to be done to fit a horizontal FoV wider than 90 degrees into a flat image. The wider the FoV, the more distortion has to happen to get it to fit. I get it all the time with my 360x180 panoramas, and I know I'm rotating correctly around my NPP. But 360 view coverage simply isn't meant to be done as a rectilinear view.

360x180 pano, equirectangular projection.
interactive view



As was mentioned, what you probably want to do is try a different projection than cylindrical. PTGui and Hugin can both do this, but it might be easier to see in Hugin (open source, so free to play with). In the GL preview window, there's a "Projection" tab that you can play with. Moving to stereographic, Panini, or Architectural might mitigate some of the distortion, but it's still going to be there, since you're basically having to take what isn't a flat view and turn it into one. Them's just the breaks.

There is something else that could cause a bowing, but your horizon looks straight, so I don't think it's this, but I don't pay attention to this any more, because I'm doing spherical panos, so it doesn't matter, I can just re-level in post. But if you vary the pitch of the camera between shots, then the horizon can bow up or down. But this kind of horizon bowing is also very easy to fix in post. In PTGui's preview window, all you have to do is drag vertically to adjust the pitch.

[jcuknz]

I have been told to get PTgui but since I do not do many panos I have npot and know nothing of its capabilities but admire Kathi's work ....
anyway I use Paint Shop Pro and since version 8 it has had the wonderful Mesh Warp which I would describe as a controlled and selective interpolation.
You place a grid with number of lines vertically and horizontally at you choice and then you can move bits of thee picture until they 'look right' or 'look better' .... or deliberately worse.
Here is a 'deliberately worse' example which caught the judges approval.
"Running Tap" where a 'failure' was rotated 135 degrees and then pushed and pulled into something I think is interesting

But more of interest to Trace this is what I would probably have done ....

Simply pulling down the shore line to a more pleasing shape?

When PSP8 came out with Warp Mesh Larry Bolch the Canadian photographer said even if you were a Photoshop enthusiast it was worth getting PSP for just this tool and it cost no more than a plug-in you needed back then with PS