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Author Topic: panos, shifts and stitching  (Read 2206 times)
didger
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« on: March 23, 2005, 10:35:28 PM »
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For your assorted questions about stitching, you can get a lot of info by searching the forum.
As for the weight, I started out with a Panosaurus (2 lbs.), which is a super cheap, but somewhat cumbersone and flimsy pano head and once I understood the basic principle, I made a series of better and lighter and more compact pano heads.  I now mostly use a 3.5 oz. carbon fiber pano head I made and that I've glued to my 1ds permanently.  It's only suitable for single row vertical stitches and only for my 50mm and 35mm lenses, but it's very effective and setting up is no hassle whatsoever, since the pano head is now essentially integral to the camera.  I've shot thousands of pano images and I'm presently in the process of assembling a lot of final images with the PTMac program.  This is working super well, but there's a big learning curve and also some clumsy implementation and bugs to work around.  Pano head is much more versatile than stitching shifted images from a shift lens, since this severely limits how wide you can go.  With a pano head it's easy to go 360 degrees.  Most stitching software doesn't work well (quite poorly, actually), so many people insist that good quality requires the shift lens method.  This is no longer true.  If you can endure the learning curve and hassles, PTMac certainly gives spectacularly good results.  Perhaps PTAssembler is just as good, but I haven't tried it for quite a few months.

In any case, there's no way to do consistently high quality panorama stitching easily.
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John Camp
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« Reply #1 on: March 24, 2005, 03:56:42 PM »
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I was most curious about the shift in perspective. If you stand back a bit from a wide print, you take it all in at once -- so if you've panned it, you're actually looking straight-on at a kind of strange rotation effect, right? If you've shifted it, it might not be so wide, but the perspective would be "correct" for a person standing back and taking in the whole print at once, n'est-ce pas?

What if you move the whole camera? Is that different than shifting the lens? This pan head that I've got has a kind of "rail" system that allows you to move the whole camera probably six inches sideways, from one extreme to the other, while holding it in precisely the same direction and attitude.

JC
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Robert Spoecker
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« Reply #2 on: March 24, 2005, 05:54:47 PM »
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These distinctions are pretty theoretical.  I doubt that anyone could look at a bunch of shifted pano and rotated pano pictures and pick out which are which.  After the fact I even often have trouble picking out which of my pictures were shot with my 18mm ultrawide and which were shot with a 35mm or even 50mm lens.  The distortion of 18mm is so great that it's hard to believe that a typical landscape picture looks totally normal.

In any case, the shift method for stitching is a lot easier, but you can do huge stitches with the rotating method.  I just (minutes ago) finished rendering a 7 image stitch that's 70 Mpixels and you can't detect any stitch misalignment or blend imperfections at any level of magnification.  Even the fastest G5 takes minutes to do the render, however.  I expect I'll be doing some stitch things that will end up at higher effective resolution than you can get scanning 8x10 transparencies.
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didger
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« Reply #3 on: March 24, 2005, 11:10:23 PM »
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Until very recently it was pretty well impossible to get really good stitches with rotational pano shots at all consistently (if ever), as you well know, Jack.  However, with the incredibly powerful stitching tools of PTMac integrated with Enblend it's now indeed possible to get perfect results if you use good lenses and technique.  I've noticed that I can't quite get such perfect results with wide angle lenses.  The stitches are off a little sometimes and even the incredible power of enblend doesn't always manage perfect blends with clear uniform skies with wide angle lenses.  When I use my 50mm or 100mm Canon lenses the results are phenomenal without fail.

Now that I've been at it for a while, I've even gotten quite efficient and fast.  Just minutes ago Kevin posted a new beta that cures the biggest irritating bug that the program still had.  Now it's just a question of streamlining the interface a bit and making everything a bit more user friendly for the beginner and fixing an additional few bugs and getting the documentation a bit more organized.  This is definitely THE stitching program.  Kevin's dedication is just phenomenal and he communicates with all us beta testers constantly and answers every question carefully and thoroughly and promptly and he implements every reasonable suggestion amazingly quickly.  I'm not sure what motivates him; definitely not money, except maybe marketing hopes for the future.

Unfortunately, this type of stitching will probably never become extremely fast and easy, since the only really reliable way to determine matching control points precisely is manually.  Even the most sophisticated pattern recognition algorithms fall short of what dogs manage, what to say of human beings.  It's worth the effort, however.  I expect to be doing things up to 200 Mpixels if I feel like it now and then.  That's about what you can reasonably get from scanning 8x10 transparency film. 20 to 50 Mpixel images are already totally routine and I can do quite few per day.
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John Camp
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« Reply #4 on: March 23, 2005, 09:36:17 PM »
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When my kid moved to California, he left me what I think is a pano head (a Manfrotto 3475 for whatever that's worth.) I have not yet started messing with it. I *have* stitched a couple of photos using software called Stitcher, and though I screwed it up, I was impressed with the possibilities of panning and stitching. My basic question is this: what is the difference between swiveling a pano head, and using a shift lens that will allow you to shift left and right? I read somewhere that shifting the lens was a better and more accurate way to make pictures for stitching. Is that correct? And what is the difference between that, and simply sliding the camera precisely sideways on the the rails of the Manfrotto 3475? Is that the same as shifting the lens? I'd like to have a few people expound on panoramic photo-taking and the pros and cons of the different methods, as it seems to be an obvious and great use of hi-res digital cameras. And Didger, if you use a pano head, doesn't it break your back carrying it up and down mountains? I think this Manfrotto thing probably weighs as much as a 1Ds.
 

JC
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howard smith
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« Reply #5 on: March 24, 2005, 03:36:28 PM »
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Shifting the lens a little has the same effect as moving the camera quite a bit.  Also, the shift is more controlled and easier to line up.

Panning allows a much wider view.

There is a difference in perspective between the two.  Panning looks like turning your head to see it all.  Shifting is a wider format from a single point of view.  I find it hard to explain.  Look at some website for X-Pan (shift style) and Widelux (rotating).
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howard smith
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« Reply #6 on: March 24, 2005, 05:07:41 PM »
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John, I think shifting the camera side to side is almost, if not tne same thing as a shift.  The big difference is an inch or so of shift is about the same as a few feet of moving the camera.

A rotating lens image can be viewed by making a long print and curving the paper, like in the corner of a room.  Then stand fairly close,  As you rotate your head to look at various places, you will see them as you did when you made the image.  And right, if you stand back and look at a shift image all at once, you see it pretty much as you saw it then.
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Jack Flesher
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« Reply #7 on: March 24, 2005, 10:01:42 PM »
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The biggest difference is with the shift-stitch you are sweeping the sensor plane across the larger image circle of the shift lens. In this way, you get a perfect stitch, since everything is recorded without the lens being moved -- even the lens distortions will line up correctly since the lens never moves.

In practice, since the lens in fact does have to move to "shift," you accomplish this feat by counter-shifting the camera the opposite direction and the same distance you shifted the lens. This has the effect of leaving the lens stationary and sweeping the imaging plane across the shift lens' larger image circle.

Cheers,
Jack
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