Stepped out pano

Discussion in '35mm Cameras' started by Dudley Hanks, Jan 5, 2009.

  1. Dudley Hanks

    D-Mac Guest

    Far be it from me to want to light up another flame war with you but the
    mistake you made was in the focal length of the lens you used and your
    camera holding technique.
    Your idea that "if D-Mac can do it, it can't be all that hard" was probably
    the reason you failed at the first attempt.

    Almost everyone I've tried to show the capture technique to on my National
    Park tours gets it wrong the first try. Why? Because they never consider an
    oblique shot or 2 might help in later assembly of the piece.

    A 60" plasma screen to display the images you are working with on the edit
    screen helps me but if you don't have a spare plasma lying around, some
    laser or ink prints on the floor might help.

    We've all seen how a long lens alters the perception of depth. It also
    alters the way a "stepped out" (can I trademark that) panorama lets you
    handle diverging planes. No one said you have to do anything in any specific
    way. The notion of holding your camera in a classic grip should be the first
    thing you abandon.

    I won't bother with detail here but I'll tell you enough to do it better
    next time. If you have a few oblique shots on hand, they can help with
    fixing the issues of diverging planes.

    You have to remove your bias for existing concepts and be prepared NOT to
    use existing methods of blending Panorama images.

    I did say earlier it is time consuming but some subjects are financially
    rewarding enough to make the effort worth while and... How many hours do
    artists spend making a painting?

    No one said you have to take images in any sequence and no one said you have
    to join them in any particular sequence.

    No one said either that you could accomplish the assembly without drama in
    Photoshop. or that you had to use the whole image from any one frame in any
    particular location on the picture.

    No one said you had to faithfully assemble the shots either. Think of it as
    a jigsaw as you are taking the shots and try to work out what part of a
    scene is likely to fit into the new scene. I use an IC recorder to record
    notes for later reference.

    People who can sketch or paint have a far better chance of getting a linear
    pano assembled properly than photographers. I doubt Mark Thomas
    () or the idiot who is taunting me to show him a commercial
    picture could ever muster enough imagination to get it right.

    But you do Bret. (was that a complement?) Get a healthy dose of adventure
    into your photography and think about what I've said before you try again.

    Keep Gordon Moat's words in you mind too: "Realize that no individual is the
    last word in technology, and all individuals are likely to maintain some
    preconceived notions of limits. If all I do is make you investigate more, or
    attempt to push past what you thought were limits, then this article will
    have been a success".

    Douglas
     
    D-Mac, Jan 5, 2009
    #21
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  2. Dudley Hanks

    Dudley Hanks Guest

    So, I take it that increasing the number of shots / amount of overlap can
    help make an image look seamless?

    Take Care,
    Dudley
     
    Dudley Hanks, Jan 5, 2009
    #22
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  3. Dudley Hanks

    Mark Thomas Guest

    Good luck, Dudley - let us know how you go. There are three major
    problems with the cheaper panorama programs:
    First is their ability to adjust differences in exposure/colour between
    frames - a good program will adjust the individual images *before* they
    do the stitch, *including* things like vignetting. Naturally you should
    always shoot the images in manual mode so the focus and exposure remains
    constant. But vignetting, use of polarisers, or even slight variations
    in light (eg cloud movement) can provide variations that mean the joins
    stand out like pupnuts in lesser programs!

    Secondly, the cheaper programs will encounter difficulties with
    distortions and even slight mismatches. No lens is perfectly linear and
    the wider you shoot your originals, the more the images will need
    'stretching' to get things to match, esp at the outer edges of the
    images. Hence the suggestion of more images, taken from further back,
    but obviously there are diminishing returns... Then there are real
    perspective issues caused by the camera not being rotated about it's
    nodal point (very rarely (ever?) is the tripod mount the true optical
    centre of the camera), and objects that may move between frames. There
    are plugins for some of the programs (Eg PTGUI has Smartblend/Enblend)
    that can help with these issues.

    Lastly, they may have memory limitations that prevent them creating very
    large (pixel-wise) panoramas.

    Like you, I love the challenge even more than the result - I have many
    panoramas in progress.. and like to share experiences with similar
    minded lunatics. (O:

    Cheers, Dudley.
     
    Mark Thomas, Jan 5, 2009
    #23
  4. Yes, increasing the number of shots will help, but the amount of overlap
    is besides the point. Ideally, you'd need a large number of very narrow
    vertical frames, which can later be stitched together (with minimum
    overlap). What you basically are trying to do is to work as a giant
    human scanner, taking a picture of one "scan line" per shot. The
    narrower your "scan lines" are - the better. With a traditional camera
    you'd have to take a large number of very closely spaced shots and then
    use only a very narrow vertical stripe from each shot, discarding the
    overlap.
     
    Andrey Tarasevich, Jan 5, 2009
    #24
  5. Dudley Hanks

    D-Mac Guest

    Brilliant!
    One person in a sea of trolls and the curious few has a handle on what's
    needed. Obviously not an Australian wannabe critic!

    Douglas
     
    D-Mac, Jan 5, 2009
    #25
  6. Dudley Hanks

    Dudley Hanks Guest

    Ah, more stuff to consider...

    I'm guessing that the non-centered tripod bolt will produce greater problems
    at a longer focal length? Whereas, problems stitching distorted corner
    areas will plague the lower focal lengths? So, the "sweet spot" of a lens
    is going to be where the benefits of one does not magnify the problem of the
    other...

    For my first try, I'll probably use the old 28 - 80mm lens that came stock
    on my old A2. It had decent optics, and might yield an acceptable tradeoff
    in it's midrange, which should be roughly equiv to 75 or 80mm (35mm equiv).
    I'm guessing that, since I'll be working on a 90 degree corner, a longer
    lens would necessitate moving back too far from the corner to keep the
    straight-on line of sight down each street at the outside edges, which is
    what I think will help to set off the houses / trees in the center.

    This could be interesting...

    Thanks, again, Mark.

    Take Care,
    Dudley
     
    Dudley Hanks, Jan 5, 2009
    #26
  7. Dudley Hanks

    Jeff R. Guest

    Yes indeed.
    Definitely a recipe for a lovely low-distortion panorama.

    My only caveat here is that the intermediate file sizes add up to almost
    unmanageable proportions pretty quickly. Unless you have a supersized
    superfast machine you'll need to produce the image in steps, flattening and
    saving at regular intervals.

    Or maybe covert all the shots into long thin strips before combining
    (allowing overlap, of course).

    Maybe its just me, but my PC starts to go silly when image size exceeds
    300Mb or so.

    Dammit!
    All this pano talk has got me itching to go out and take some new ones...
     
    Jeff R., Jan 5, 2009
    #27
  8. Dudley Hanks

    Dudley Hanks Guest

    So, it's preferable to put the camera in the portrait orientation? Then,
    sstrip the sides off to get a long, narrow strip for each shot? Then,
    stitch the altered shots together?

    This really is going to get interesting...

    I think for my first pano, I'll keep it simple, and will just do the
    basics... Landscape orientation, a minimal number of pics, and let the
    program do its thing.

    I'll try both programs to see how each performs, and see how badly you guys
    can tear the result apart. :)

    That should give me a good idea of the limitations of my camera / lens /
    tripod, and I should then be able to make adjustments to later images for
    better results.

    Take Care,
    Dudley
     
    Dudley Hanks, Jan 5, 2009
    #28
  9. Dudley Hanks

    Jeff R. Guest

    Now this is an interesting admission, Doug.
    Are you saying here that it doesn't matter if the final stitched result
    *isn't* a faithful rendition of the original scene? Just so long as it
    *looks* seamless and complete?

    If that is indeed your philosophy, then it explains a lot of the "features"
    of your Tangalooma stitch-up.
    (Extra bits, missing bits, truncated footpaths etc.)

    No - no-one *said* you have to faithfully assemble the shots. I guess some
    things are kind of assumed.

    Actually, Doug, I'm quite a dab hand at sketching. I have a good handle on
    perspective, both mechanical and freehand, and I do understand the concepts.
    You know nothing about me Doug, and you shouldn't assume.

    Let me summarise:

    * Rotated panoramas exhibit a pair of vanishing points. Just two. Maybe even
    just one - depending on the composition. (I'm simplifying here, but..)
    * Linear panoramas need to suppress the VPs, by presenting the visual
    information in one plane only - effectively 2D instead of the ersatz 3D of a
    perspective image. If they do suppress the VPs, then they work perfectly.
    If, on the other hand, the constituent images of a linear pano *have*
    perspective (and VPs), then the task of combining them will be fraught with
    error. M.C.Escher himself wouldn't bother. The final image would contain
    more VPs than there were images. It would be a distorted mess which would
    bear little or no resemblance to real life. Straight lines would need to be
    rendered as sine curves.

    But - if you have no interest in faithful rendition of the scene... well...
    For Crissake Doug - buy a dictionary!
    Yes Bret. Just make it up if it doesn't fit.
    Works for Doug.
     
    Jeff R., Jan 5, 2009
    #29
  10. Dudley Hanks

    Jeff R. Guest

    Only if you need the extra resolution that this will provide. In practical
    terms, no, because you're going to end up with huge files and plenty of
    resolution anyway.

    We are talking, here, about an "ultimate" digital panorama - not an everyday
    one.
    It is.
    Panos are a lot of fun.
    Good idea.
    Overlap by -say- 20% or so (that should be plenty) and limit the number of
    shots. Four or five is plenty.
    Two is enough.

    A tripod helps a lot if you don't want the horizon to "fall down" as you go.
    Pfft!
    As if we'd do that.

    BTW - and this doesn't constitute "advice" (just a comment)...
    I've used half a dozen or so of the commercial pano assembly programs,
    including the macros built into PS, and I still prefer hand-assembling in
    PS.
    All the commercials do the job, some pretty well, some hilariously badly,
    but I find nothing beats time at the PC, tweaking levels and pushing and
    pulling lines. Just my 2ยข.
    Unless you're using a cellphone camera, you won't find your equipment is the
    limitation.
    Focal length(s) is an interesting issue - but more on that later.

    Hooroo
     
    Jeff R., Jan 5, 2009
    #30
  11. Dudley Hanks

    MJW Guest

    Watch out for the Canon Auto-Stitch, Dudley. I
    found that the seams in the stitching were very
    noticeable. Got a trial of PT-Gui, re-did the same
    pano through it, seams were gone. I bought a copy
    of PT-Gui that afternoon!

    --
     
    MJW, Jan 5, 2009
    #31
  12. Dudley Hanks

    Mark Thomas Guest

    It gets worse - you are joining an elite club of strange, obsessed
    individuals...
    No.., it's more about objects *close* to the camera. At close
    distances, the parallax error is *relatively* large (umm, did that make
    sense?). If you are shooting with a longer focal length, most of your
    scene content is likely to be far enough away that you (or your pano
    software) won't have much difficulty.

    I don't hesitate to do normal panoramas, (ie landscapes or anything with
    most content beyond about 3-4m) at moderately wide angle, eg 35mm or
    even 28mm. But that is partly because most pano software does such a
    nice job at 'undistorting'. Sure, you might get a slightly better
    result with many more longer f-l images, but that increases your
    taking/storing/stitching time and effort. In a scene where the light is
    changing rapidly (eg dusk) you may want to get the images *fast* and
    some scenes simply aren't worth it. Experiment to find out what works
    for you - but if it's a nice scene and you have time, err on the side of
    overkill.
    Yes, but if you leave a reasonable overlap and your software is capable,
    that isn't a huge problem as long as you don't go too far down -
    fisheyes are not a good idea! Also, if shooting wide, leave plenty of
    overlap *not* just for the joins, but also around the *entire periphery*
    of the scene. Your software may have to distort the images quite
    dramatically, and that will mean you will have to crop off a lot to
    remove the curved edges.
    You got it. If in doubt, shoot at 50mm (35 equiv) or a bit longer for
    easy stitching. That's also a f-l where most mid-range zoom lenses
    perform near their best..
    All makes sense - keep us posted! More than happy to help, and also
    happy to offer suggestions or even run some images through
    PTGUI/Smartblend if you want run into difficulties or want some
    demonstrations.
    Always a pleasure, Dudley.
     
    Mark Thomas, Jan 5, 2009
    #32
  13. Dudley Hanks

    Dudley Hanks Guest

    Thanks for the tip.

    I'm sure it will end up on my 2buy list shortly after I finish my first
    couple of pano's...

    Take Care,
    Dudley
     
    Dudley Hanks, Jan 6, 2009
    #33
  14. Dudley Hanks

    Troy Piggins Guest

    MJW wrote :
    I use Hugin http://hugin.sourceforge.net/
    It's free and does a great job of stitching. I'm talking about "normal"
    panos, not these so called "stepped out" panos. They may be possible, but
    I don't have the inclination to give them a go at the moment.
     
    Troy Piggins, Jan 6, 2009
    #34
  15. Dudley Hanks

    Troy Piggins Guest

    Dudley Hanks wrote :
    See my recent followup to MJW's about hugin - it's free and quite capable.
     
    Troy Piggins, Jan 6, 2009
    #35
  16. Dudley Hanks

    Dudley Hanks Guest

    I REALLY wish I could see that pic...

    Take Care,
    Dudley
     
    Dudley Hanks, Jan 6, 2009
    #36
  17. Dudley Hanks

    MJW Guest

    I'm actually thinking about giving one a go, just
    to see what happens!

    --
     
    MJW, Jan 6, 2009
    #37
  18. Dudley Hanks

    Jeff R. Guest

    Not so much "close enough".
    More "perpendicular to the axis of the camera".
    Then the image would be a "flat", "2D" image which would stitch together
    just fine.
    Yup.
    Even the deep recesses wouldn't need to matter, so long as they were
    contained within one image. (Overlapping and merging them would be
    problematic)
    Not sure what you're getting at.
    Do you mean a rotating pano, with the camera at the apex of the corner, or a
    linear pano, walking around the corner and aiming at the buildings?

    If the former - no probs. (But you may find the appearance of the road a bit
    strange when you've assembled it)
    If the latter - fine - so long as the buildings are straight-on to the
    camera. You won't get the effect of the 90 deg corner, though.
    Hehe.
    I'll say.

    Still - a single A4 sheet can display a nice pano.
    Or - (hehehe) - you could print it out on a series of sheets and stick it
    together.
     
    Jeff R., Jan 6, 2009
    #38
  19. Dudley Hanks

    MJW Guest

    Troy, I have just d/loaded & given Hugin a go. Its
    pretty good. Thanks for the heads-up!

    --
     
    MJW, Jan 6, 2009
    #39
  20. Dudley Hanks

    D-Mac Guest

    Take out the rubbish and what's left?
    Comments from an idiot with no talent and no ability to get any.

    At least someone took you seriously. I guess you have to be a kook to find
    one!

    Welcome to my BOZO BIN.

    Your have some familiar company, all disgusting trolls trying to stuff up
    other newsgroups after you'd done over aus.photo. Good luck mate. I hope the
    3 of you get some brains whilst in the bozo bin.!

    Try someone else in future. I won't play any more.

    Douglas
     
    D-Mac, Jan 6, 2009
    #40
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