"Virtual" wide angle via stitching seems to have less distortion

Discussion in 'Australia Photography' started by rowan194, Jun 30, 2006.

  1. rowan194

    rowan194 Guest

    I was playing with a 3x3 stitched image today and for fun did a
    comparison with a standard single shot:

    http://satin.sensation.net.au/rowan/widecompare.jpg

    I found it interesting that although the stitched image has a
    noticeably wider FOV, there's a lot less perspective distortion.

    Unfortunately, it's a lot of work (and CPU time) to stitch 9 images
    into one!
     
    rowan194, Jun 30, 2006
    #1
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  2. Since the software has to do a little stretching when it does the
    stitching, I suggest that it is correcting some of the distortion, just as
    you might have done to the single image.
     
    Joseph Meehan, Jun 30, 2006
    #2
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  3. rowan194

    Alf92 Guest

    rowan194 () a écrit
    dans :

    yes.
    however, some software (even freeware) exit to correct te lens distortion.
    like this one : http://www.photo-freeware.net/ptlens.php
     
    Alf92, Jun 30, 2006
    #3
  4. rowan194

    Pete D Guest

    I have done some good 7 shot wides and one 13 that was far more than one
    lens could do.
     
    Pete D, Jun 30, 2006
    #4
  5. rowan194

    bugbear Guest

    bugbear, Jun 30, 2006
    #5
  6. rowan194

    kosh Guest

    as you would expect shooting at a more standadard focal length for the
    stiched shot.

    to avoid prbelms with distortion when making long panoramas I generally
    get best result around the 40mm equivilant. When I do this the stitches
    are often seemless.

    kosh
     
    kosh, Jul 1, 2006
    #6
  7. rowan194

    Nige Guest

    yes, most books on the matter suggest using normalish (50mm) focal
    lengths. They also suggest turning the camera into 'portrait' mode to
    get more vertical coverage and take more frames to cover the horizontal.

    Nige
     
    Nige, Jul 1, 2006
    #7
  8. rowan194

    Don Wiss Guest

    The reason you do that is you have the best stitch results if the middle of
    your picture lines up with the horizon. And in the portrait orientation
    you'll get more of the scene below the horizon.

    Don <www.donwiss.com/pictures/> (e-mail link at page bottoms).
     
    Don Wiss, Jul 1, 2006
    #8
  9. For those of us stuck in the Point&Shoot world, this is easy advice to
    follow. My latest attempt at stitching, 3 frames with an FZ5 (widest
    focal length 36mm):

    http://ri22.uchicago.edu/~dmsilev/tibetan_concert.jpg

    It stitched pretty well, except for a few inconsiderate people in the
    foreground who moved around a bit between frames.

    -dms
     
    Daniel Silevitch, Jul 1, 2006
    #9
  10. Stitching is great fun...but the reason it doesn't distort is 1) software
    correction and 2) you are not using an extreme wide angle....so you start
    with less distortion.
     
    Gene Palmiter, Jul 1, 2006
    #10
  11. rowan194

    kosh Guest

    overage and take more frames to cover the horizontal.
    asssuming you plan on ignoring the rule of 1/3's that is.
     
    kosh, Jul 1, 2006
    #11
  12. rowan194

    Guest Guest

    Interesting comments on photographic "rules" at
    http://theonlinephotographer.blogspot.com/
    including the following advice from contributor Ken Tanaka --

    "... But don't, don't, do not start confining your creative ambitions with
    "RULES."
    They do not exist. Take the pictures that you like to take and let your own
    frustration
    be your guide to developing your own set of best practices. You may, indeed,
    find that,
    say, the "rule of thirds" works for your own eyes, or not! "

    Also on the site are examples of great photos, together
    with the cliche "rules" that they've broken.
     
    Guest, Jul 1, 2006
    #12
  13. Pretty spot on, but taken solely at face value, is misleading. Rules of
    thumb do exist, and for tried and true reasons.

    BTW, if you do not hit Return as your text approaches the edge of your
    compose window, you won't get odd wrapping as above.
     
    John McWilliams, Jul 1, 2006
    #13
  14. rowan194

    Don Wiss Guest

    That can be fixed. If you stitch with PTGui you can output as TIFF files
    and then mask out the people in the layers where you don't want them. I
    have seen web pages explaining this, but I haven't bothered to do it
    myself, yet.

    Don <www.donwiss.com/pictures/> (e-mail link at page bottoms).
     
    Don Wiss, Jul 1, 2006
    #14
  15. But in this case, the rule of thumb to level your panorama with the horizon
    over-rules the rule of thirds rule of thumb.

    The reason is simple. I have a true panoramic camera (swing lens) and if
    the horizon isn't perfectly level it will come out curved. Sometimes this
    can create an interesting, if gimmicky effect, but for a normal looking
    photo it simply has to be level with the horizon.

    The same thing happens with stitching software. If you tilt the camera up
    or down, depending on which software you use, the result will either be a
    curved horizon, strange distortions or it won't stitch properly. There are
    ways of correcting for tilt with some software, but it's much simpler to use
    a spirit level and keep the camera level when you take the photos in the
    first place.

    If you want a rule of thirds horizon after you've stitched your pano, it's a
    simple matter to crop afterwards, much easier than taking the shots tilted
    and making it harder to stitch.

    In fact, it can often be difficult to visualise what a stitched pano will
    eventually look like so it's worth covering a larger area than you think
    you'll need in order to give yourself some leeway for a nice crop
    afterwards. It's really annoying to cut the edges too fine then find that
    you have bits missing in the final image, since some cropping is
    unavoidable.

    Paul
     
    Paul Saunders, Jul 1, 2006
    #15
  16. So use a different tool. Use a shift lens. On a 1.6x camera the +/- 11 mm of
    shift provided by the Canon TSE lenses means that with the camera mounted
    perfectly level, you can place the horizon anywhere from 3 mm above the
    frame to 3 mm below the frame (landscape orientation of the camera) or
    anywhere from 1 mm from the top of the frame to 1 mm from the bottom of the
    frame with the camera mounted vertically.
    So use a shift lens to get the composition you want...
    But the above is _really really really_ good advice. I shot the following
    one at 13mm (300D + 10-22mm) and should have used 12, or even 11 (the
    building at the left got clipped). Oops.

    http://www.pbase.com/davidjl/image/43504169/large

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Jul 1, 2006
    #16
  17. rowan194

    Mr.T Guest

    Good advice for those who can justify it's cost. (or a proper view camera
    even.)
    For those who can't, more shots and more work in photoshop is required.

    MrT.
     
    Mr.T, Jul 1, 2006
    #17
  18. I thought about doing that, but haven't had the time to play around with
    it yet. I could make my life easier by just cropping out the whole
    foreground, but I think the crowd of people adds enough to the picture
    that I'd prefer to keep them in.

    -dms
     
    Daniel Silevitch, Jul 1, 2006
    #18
  19. Not an option, swing lens cameras don't use interchangeable lenses. In
    spite of their limitations they have one big advantage over stitched panos -
    the ability to include movement, for example crashing waves on the shore,
    branches swaying in the wind, or even fast moving clouds racing across the
    sky.
    That would be an option, but to be honest I don't take that many stitched
    panos and I don't find it a problem to level the camera and crop later. Now
    that I've got PTGui, curved horizons can be corrected fairly easily anyway,
    or I could take multiple rows of shots and simply keep the central row
    levelled.

    As a general rule though, I try to choose a viewpoint which gives me as much
    interest above as below the horizon so that the image doesn't need to be
    cropped. Provided there's no actual horizon visible in the image it's not
    likely to offend the rule-of-thirds fantatics.
    Very nice image, almost... :)

    I've often made that mistake in the past. The thing to remember is that
    it's the centre of the edges that bulges out when lens distortion is
    corrected, so that's what tends to get clipped. If there are important
    details that you don't want to be clipped, try to ensure they are visible in
    the corners of the frame as you pan.

    Paul
     
    Paul Saunders, Jul 1, 2006
    #19
  20. Sorry, I meant "use a shift lens, a leveled tripod, and stitching software."
    If you create a cylindrical projection, you get pretty much the same effect
    as a swing lens.
    Yep. Although the swinging lens can introduce similar infelicities as one
    occassionally sees with focal plane shutters. But things like tree branches
    and people moving can often be handled by setting up the image so the motion
    doesn't fall on an overlap.
    Yep. It's usually not all that much of a problem in real life. I've been
    thinking about doing urban panoramas from landings on buildings, here, and
    for that it would be nice.
    And it's not a hole in the ground any more :-(

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Jul 1, 2006
    #20
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