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Author Topic: Some Panorama advice (needed)  (Read 6179 times)
Lisa Nikodym
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« on: April 28, 2005, 03:53:00 PM »
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I've only done a handful of panos (also with a D70 with kit lens ), so I'm no expert yet and don't feel qualified to answer your first two questions, except to say that I managed the five-shot pano below at the 18mm end of the kit lens:

click here

I didn't notice distortion being a problem. The only problem was that, because I wasn't using a calibrated panorama head, there was some misalignment ("ghosting") of parts of the grassy areas in the foreground which I had to fix with some cloning.

On the subject of your third question: If you don't use a tripod, your camera motions from frame to frame will be *much* less well-controlled. You'll have some up-and-down motion between frames that will mean your cropped image will be smaller than it otherwise would have been. After doing a couple each way, I'm now a big fan of tripods for panos.

Lisa
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LiorT
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« Reply #1 on: April 29, 2005, 01:44:56 AM »
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OK, thanks guys.

BTW - Do you suggest doing the stitching in photoshop or use a 3rd party application ?

LT
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dandill
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« Reply #2 on: April 29, 2005, 11:22:16 AM »
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For fun, see the free program

AutoStitch

The results are fast and amazingly good.

I do think PanoTools with PTAssembler/PTMac are the way to go, for maximum flexibility and highest quality results.
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Dan Dill
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« Reply #3 on: April 30, 2005, 08:54:16 AM »
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I'm a believer in the principle of KISS to the extent consistent with the quality I want.  I don't want foreground ghosting due to parallax from not using a tripod and calibrated panorama head.  I don't want the inevitable stitch misalignments you get with overly simple software and that WILL be visible in large prints.  I like to think that I DO know what I'm doing after carefully testing so much stitching software and now doing thousands of stitch shots with the one stitching program (not very simple) that I've tried that actually works perfectly and consistently.  Your mileage may vary according to your standards of quality and how much pano shooting you actually do and what kinds of subject matter and how carefully you look at your results and at what level of magnification.
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Lisa Nikodym
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« Reply #4 on: April 30, 2005, 04:17:08 PM »
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Some folks may be OK with ultra simple free programs that limit you to post card prints or emailing a picture to a friend, others may want to go a bit better than that, and others may want perfect prints right to the limits of what the file can support.

Just for reference, the panorama of mine that I have a link to above was stitched with Panorama Factory, and I have a 16"x32" print of it (bigger than a post card!) on my wall. The only stitching problems I found were "ghosting" in the foreground areas, but that's due to parallax since I wasn't using a panorama head at the time. If there were misalignments anywhere else, I think I would have seen them in the big print. On the other hand, it's a single example; there are probably other examples that PF would fail on where PTAssembler won't.

Lisa
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Lisa Nikodym
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« Reply #5 on: May 01, 2005, 12:57:55 PM »
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An additional thought that occurred to me:

The issue of distortion at wide angle isn't as bad as you would think, since some (many? most?) stitching programs correct for barrel distortion, light fall-off, etc. as part of the stitching, after you tell it what kind of camera you're using and it automatically detects the focal length.  (At least that's how Panorama Factory works, and I imagine many others do too.)

Lisa
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didger
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« Reply #6 on: May 01, 2005, 03:19:43 PM »
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As for distortion and automatic correction; the problem is that the distortion is not regular and predictable enough by the program math to match the particular charactaristics of the lens accurately enough.  Even if you specify several control points accurately manually, you still get misses because of this lens irregularity.  The wider the lens the more problems you have even with single pictures and these problems get a bit magnified with stitches.  At any rate, I try to avoid very short focal lengths for stitching (or even otherwise if there's alternatives).  Most stitch programs support wide angle lenses in some way or another, but I've never been able to get the results anywhere near as good as at 50mm or longer.  Even my Tamron zoom at 28mm (which is not very wide for 1.6 factor camera) doesn't do well enough.  I'm better off using a longer focal length and shooting vertically and using more frames for a given final FOV.  I love very wide scenes, but not very wide lens quality.  That's why I'm such a stitching fanatic.  

I would much welcome any feedback from folks with perhaps more experience with all this (experience rather than just ideas).  Maybe I could do better than I've been able to do so far.

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Nudge, nudge ;-)
I did go to the site and looked and read.  I just don't have the energy to try one more auto-everything stitching program, especially PC, which has basically become a non-platform for me any more.  Having now got a huge amount of experience with the challenge of finding good matching control points manually based on very careful visual pattern matching, I simply don't believe any more that any algorithm can do as well.  Now if someone thoroughly tests this program and makes a convincing case that this can do very good stitches with fairly challenging input, I could maybe be nudged a bit more.
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didger
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« Reply #7 on: May 01, 2005, 05:48:26 PM »
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may, hopefully, find their way into other tools.
Well, something of the sort has found its way into Stitcher 4.0 quite some time ago, at a price of $400 for a package that I did not think worth buying.  The results were good when it worked, but all too often it didn't work for me; a message that Stitcher can't do an automatic stitch, do you want it to do a "forced stitch"?  This was generally not good, and a lot of times a forced stitch was also not possible, and then the suggested method is manual alignment, with no correction for distortion, etc.  Besides the problem of these unsalvageable failures, the required huge overlap is also a nuisance that fills CF cards too fast.  I wonder how this new thing will really work; you can't tell anything from the picture on the web.  The program is obviously still a pretty early beta, with no commercial distribution.

PTMac has some optional auto features that don't work for me.  Fortunately, you can get pretty fast at manual control points.
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didger
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« Reply #8 on: May 04, 2005, 02:33:41 PM »
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An article wouldn't challenge my web space, but it would challenge my time, and then whatever I could write would be for my work flow, my particular aims with pano projects, and Mac only.  Then after all that, there's the countless follow-up questions.  The good news is that PTMac is very well supported with personal tech support.  Kevin (the programmer) answers personal emails and also answers questions on his forum quite regularly and there's senior beta testers that also often have good answers.  Unfortunately, getting started is a bit difficult, since there's no real manual.  There's a sort of OK help section that's not complete enough, though.  It took me an incredible amount of time to get familiar enough with PTMac to get efficient (with the tiny percentage of what the program can do that I care about) and an equally lot of time and experimental designs of more and more efficient carbon fiber panorama heads, again to do exactly what I want to do, and now only for the D2X.  At least now PTMac really does work for exactly what I wanted all along, though it took a year of pestering Kevin to implement a few things that are absolutely crucial for me.  I wish I had an easy answer, but I'm afraid there ain't one.
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LiorT
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« Reply #9 on: April 28, 2005, 03:02:49 PM »
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Hi,

I've been a photographer (as a hobby) for a couple of years now, but I've never actualy did any panorama, Following the "Adventures with Panoramas" article I decided I've left this out for too long, so I'm going out on a shoot tomorow just as a trial to test the theory in the field (to grasp the basics and draw conclusions)- but I have some questions first.


first - focal length - I'm in a transitional phase where I'm moving from Minolta to Nikon (yes.. yes.. shame on me), So right now all I have is my D70 and the kit lens.
What FC should I use ? 50mm should give less distortion then 17 but then 17 is wider... (or maybe 70mm?) I'm going to shoot mostly *distant* landscape. Some feedback (pro/cons) would be welcomed.

second - is cropping of the top/bottom parts of the photo (I'm going to shoot vertically) recommended to keep distortion to a minimum ? (is this something I need to keep in mind when I shoot ?)

third - the article mentioned the writter didnt like tripods - I'd like to hear from other panorama-expirienced photographer if this is your recommended aproach as well ? (as a pro and also as an advice to a novice)

I hope I'm not totaly without a clue with these questions.
thanks in advance
LT
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Lin Evans
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« Reply #10 on: April 28, 2005, 05:41:15 PM »
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first - focal length - I'm in a transitional phase where I'm moving from Minolta to Nikon (yes.. yes.. shame on me), So right now all I have is my D70 and the kit lens.
What FC should I use ? 50mm should give less distortion then 17 but then 17 is wider... (or maybe 70mm?) I'm going to shoot mostly *distant* landscape. Some feedback (pro/cons) would be welcomed.

second - is cropping of the top/bottom parts of the photo (I'm going to shoot vertically) recommended to keep distortion to a minimum ? (is this something I need to keep in mind when I shoot ?)

third - the article mentioned the writter didnt like tripods - I'd like to hear from other panorama-expirienced photographer if this is your recommended aproach as well ? (as a pro and also as an advice to a novice)

I hope I'm not totaly without a clue with these questions.
thanks in advance
LT

I agree with Lisa - use a tripod!  If you shoot vertically you will have much better control with a tripod because it takes many more frames with the loss in overlap to get a decent wide image.

As for the focal length, the 17mm will actually look like a 26mm (25.5) with your D70. This effectively uses less of the distortion producing part of your lens (outer periphery) since the circle of definition is cropped from the more central part.

For really distant landscapes you probably will do better with a 50mm or 70mm simply because a wide angle is not going to be quite as sharp - just the nature of the beast. The wide angle would be preferred "if" you are planning a hyperfocal (focus on closeup and infinity and everything in between) type shot such as a meadow of wildflowers with a mountain range in the background. Primarily this is because the wide angle will focus much closer than the 50mm or any telephoto (70mm, etc.).

For most landscapes you won't need a spherical pano head unless you stitch more than one row. By shooting in the portrait orientation you probably won't need to worry much about needing more than one row to cover the desired field of view, but if you do find you are shooting tall structures which take more than one overlapping row, you will want to consider a spherical pano head.

Unless there are objects in close proximity to the lens in the frame, rotating on the entrance pupil (sometimes called nodal point) isn't a rigid necessity, but my suggestion is to find the proper rotation point and use a pano head which will accommodate adjustment to allow rotation at this point because it will greatly ease the sitiching issues. There are some inexpensive pano heads available which will support a D70 and if you plan on doing much of this you probably should look into one.

Best regards,

Lin
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Lin
didger
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« Reply #11 on: April 29, 2005, 03:43:54 AM »
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I spend a few hours a day shooting even when I'm home (close to Joshua Tree NP) and I'm mostly not home, but out shooting in other areas.  I do almost nothing but panorama stitch shooting and yes, I agree about advantages of tripod and panorama head.  You can get by without the panorama head if you only shoot distant subjects with no close foregrounds.

As for software, I've tried about everything there is for Mac and PC and I've found that only PTMac gives absolutely perfect results absolutely consistently with practically all lenses.  I haven't tested PTAssembler for a while and I assume it's now also good.  Both programs have a substantial learning curve, but if you're serious about pro quality stitched images it's worth it, and once you've mastered the process (calibrated panorama head and the right software) it all becomes quite fast and efficient.  Once you learn the principles of it all and you understand how a panorama head works you can design something lighter and more stable for you particular camera.  This is especially easy if you limit yourself to single layer.  My latest version (#5) weighs about 5 oz., is rock solid stable, and accomodates my Nikon 12-24mm, Tamron 28-75mm (both at all focal lengths) and Sigma 105mm.  First learn what's what with the Panosaurus.  It's cheap enough as a learning tool, though too cumbersome and unstable as a serious production tool.

I would not recommend ultrawide lenses for stitching.  For your camera that would be something on the order of 12 to 17mm focal length.  The distortion of all such lenses compromises panorama stitch quality and there's usually also blend problems because these extremely wide lenses generally have substantial differences between the left and right sides.
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Paulo Bizarro
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« Reply #12 on: April 30, 2005, 05:55:27 AM »
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I do some panoramas now and then just for fun, nothing serious. I use the panorama assist mode on my Powershot Pro1, very useful and intuitive.

Later, I use Photo Stitch, the software that came with the camera. I am a believer of the KISS principle, and the software really works great.

I have done panoramas both with and without a tripod; as long as you know what you are doing, and of course depending on the light levels, it is not such a big issue. More important is to understand that light levels should not change dramatically along the panorama. For instance, it works better with distant and front-lit subjects. Otherwise, you end up with blue skies in one end, and whitened skies on the opposite end.
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Lisa Nikodym
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« Reply #13 on: April 30, 2005, 10:06:42 AM »
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Regarding stitching software:  I found that Photoshop's stitching capabilities worked pretty poorly, often failing on even simple stitching cases.  I tried PTAssembler (the complicated one) and a couple of more user-friendly ones (the ones that didger finds don't work as well).  Of them, I found PTAssembler to have a large learning curve, which I haven't gotten around to spending the time to do yet; in the meantime, I found that Panorama Factory is incredibly quick and easy to use (and pretty cheap) and usually gets it close enough to right for my purposes, so I've been lazy so far and been using PF.

Lisa
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didger
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« Reply #14 on: April 30, 2005, 01:54:15 PM »
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Hey, Lisa, great "center of the road" distillation.  Some folks may be OK with ultra simple free programs that limit you to post card prints or emailing a picture to a friend, others may want to go a bit better than that, and others may want perfect prints right to the limits of what the file can support.  The last requires a learning curve and careful manual selection of control points or the big expense and imperfect reliability of Stitcher 4.0 (and the huge overlaps this program requires and still a considerable learning curve).

As for KISS, I'm reminded of what Einstein said about KISS related to scientific theories:  Keep it as simple as possible, but no simpler.  Extremely simple and very high quality stitching just ain't possible.  Pick your own level of comfort, as represented by the various levels of Pbizarro, Lisa, and myself.  Above all, have fun.
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didger
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« Reply #15 on: April 30, 2005, 08:12:22 PM »
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I got some acceptable results with most of the programs I tried (excluding Photostitch and Photomerge).  I think with extremely careful level shooting with any really good 50mm or longer lens you could get good results with a lot of these programs.  However, if your shooting isn't level, so that there's left-right tilt of the camera, or if you're using wide angle lenses the stitching won't be right without manually specifying control points.  In any case, I generally didn't have much luck with anything except PTMac and Stitcher 4.0 most of the time if the overlaps were big enough.  The way I shoot now, I'd never get good results without manually selecting control points because I don't make any attempt to level each shot.  I don't even use a bubble level at all; just get each shot in the series so it looks about right.  If you specify control points accurately, you get perfect stitches since the program stretches and squeezes the images so that everything lines up regardless of distortions from the lens or from camera tilts in any direction.  It's very liberating in the field not to have to be so extremely precise about camera leveling and I've gotten very fast at determining control points.  The learning curve, however, would not be attractive to someone just doing an occasional pano stitch.  For me it's my main thing now and it needs to be 100% reliable and it needs to be no hassle whatsoever in the field.

If you want to test your methodology effectively without looking at images super carefully at 100% view along the stitch line, the best way is a scene with several power or phone lines at various angles in the sky and with a pile of cut wood at random angles in the foreground.  You can see mismatches very easily.  For stuff like sand and grass you might miss pretty major mismatches altogether without looking very carefully, especially if the program blends along stitch lines pretty well.  No blend can disguise mismatched wires in the sky or mismatched cut wood edges.  That sort of subject matter provides the moment of truth.
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dandill
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« Reply #16 on: May 01, 2005, 01:38:05 PM »
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AutoStitch

Nudge, nudge ;-)
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Dan Dill
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« Reply #17 on: May 01, 2005, 05:36:14 PM »
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Quote
Nudge, nudge ;-)
Having now got a huge amount of experience with the challenge of finding good matching control points manually based on very careful visual pattern matching, I simply don't believe any more that any algorithm can do as well.  Now if someone thoroughly tests this program and makes a convincing case that this can do very good stitches with fairly challenging input, I could maybe be nudged a bit more.
I am of the same mind, that carefully assigning control points manually, etc., leads to the best results. What caught my interest about AutoStitcher is that it seems to be a proof of concept that very high quality result can be gotten "automagically" and so that its authors have made some significant algorithmic advances that may, hopefully, find their way into other tools.
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Dan Dill
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« Reply #18 on: May 04, 2005, 01:12:10 PM »
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I just got back prints from using Autostitch.  The prints are 6.5" x 29".  The shots were from slides scanned at 2800 pdi.  They were shot with a 24mm lens on a tripod without a pano head.  I just couldn't get the image to come out right using PTGui, so I was surprised that Autostitch actually churned out a better image.

So far I've found that it works for some and not for other images.  Surprisingly, on some images were I've used a pano head Autostitch has failed.

didger, I would be interested in reading an article about how you use your stitching program.  Many of the articles that I've read are way to technical, and think you could do a good job at writing one and explaining it to users who don't want to bury their heads into articles on the internet for days and days of research just to figure stitching out.  If you did something like this and Michael didn't want to publish it, I'd happily put it up on one of my sites, since you said you were running out of room on yours.
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