matching almost identical photos

Discussion in 'Digital Photography' started by Jar Jar Binks, Aug 2, 2007.

  1. Hi everybody

    I'm currently in the process of building a house and I'm documenting
    (almost) every step photographically and want to use these pictures in a
    film making it look like a time lapse movie. I take all the pictures from
    the same spot, but of course there are slight differences in angle and tilt.

    Does anyone of a software that will align/correct the pictures so there is
    no or minimal jerking to the movie? Thnks for any advice!

    Pete
     
    Jar Jar Binks, Aug 2, 2007
    #1
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  2. Jar Jar Binks

    WhoDat Guest


    By angle and tilt I presume you mean horizontal & vertical subject placement,
    and slight rotations caused by hand-holding a camera from one frame to the next.
    If the tilt you are talking about is parallax perspective changes from taking
    photos of the same subject from slightly different places then that will be more
    difficult. You say, "from the same spot" so I assume this isn't what you mean by
    "tilt".

    If parallax perspective distortions are not part of the problem you can use this
    freeware HDR Alignment Tool

    http://www.flickr.com/groups/hdr/discuss/72157594229411664/

    It's used to align hand-held multiple exposures for HDR techniques, but can also
    be used for doing animations. Any process that requires you to overlay similar
    parts from one image to the next. It will crop all your images to the largest
    size that would keep your subject's control-points aligned. The tedious part
    will be selecting alignment control-points (features that are identical) in each
    image. This sure beats trying to do the all rotating, scaling, and cropping
    manually though.

    It will also correct for lens perspective distortions by calling up various
    camera lens values from a PTLens database (read the included readme file). This
    might be handy if you need to compensate for some wide-angle barrel distortions
    to help keep the sides of your buildings and construction materials as straight
    lines.
     
    WhoDat, Aug 3, 2007
    #2
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  3. Here's how I would do it. I have PSE as my editor software and it allows me
    to vary the opacity of each layer. So I would stack the photos as a series
    of layers. Then I would turn off (or set visibility to off) all but the top
    and bottom layers. Then turning the opacity of the top layer down a bit I
    can see both the top layer and the bottom layer through it. Then using the
    move tool I would adjust alignment of the top layer to match the bottom.
    Then set the top layer to 100% opaque and save the result as a PSD. After
    deleting the top layer I would repete the operation for each frame/layer
    until I have a series of saved PSD files. Finally I would load each of the
    PSD files and flatten each for resaving. When you flatten the "hidden"
    layers will be deleted and you will end with only the top, 100% opaque
    image. Just save these images in whatever format you need for the animation
    software you wish to use. The reason for saving in PSD and then going back
    to flatten is that when you flatten, all the hidden layers go away and you
    would have to reload all the lower layers and start over for each successive
    layer. But by saving each of the completed layers as a PSD, the subsequent
    layers are retained until you get to them. Then flattening the individual
    saved versions of the stack can delete the lower layers without any worries.

    This is a rather involved way to do what you want, but it actually seems to
    be faster to do than to type the explaination (for me).

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Aug 3, 2007
    #3
  4. Jar Jar Binks

    WhoDat Guest

    You could have made this easier by leaving the layer you were working on at 100%
    opacity but setting its property as a "difference" layer. Setting it back to a
    "normal" layer after alignment. This way anything that wasn't different between
    the two would appear as black, making seeing alignments fast and easy. The other
    change from your method is that I would use about 1/3 the amount of steps you
    take by stacking them all in the editor at one time as layers, then making only
    the base-layer (the background) and the one I wanted to work on as visible. When
    done aligning one layer turn off its visibility and turn on the visibility of
    the next frame/layer. Set it to a "difference" layer type, align, turn off
    "difference" and then onto the next. Then crop the whole lot of them all at
    once. Even though this method is faster and easier than yours, it was still
    extremely tedious to say the least. Now I just use that HDR Alignment Tool
    mentioned in my previous reply, saving many many hours of work.
     
    WhoDat, Aug 3, 2007
    #4
  5. Your ideas are good too. The reason I tend to do all the loading at once is
    because I find the loading and copying of layers works smoother for me when
    I do it all at once. But you are correct you could only load the bottom and
    top layer and then you could flatten and save the image all in one step.
    As to the difference layer, I have not used it very often and so don't think
    of it first. And since there will definately be differences between layers
    due to the construction (which is what the movie is all about) the
    intentional differences may confuse the allignment process, IMHO. But with
    opacity it would be easy to line up a roof line and a downspout (for
    example) by moving and rotating the top layer to visually line up the two
    images.

    But you are correct that there are many possible ways to do what the OP
    wants, and choosing between them will be a case of personal preference. So
    the more suggestions we give, the more choices the OP has to try. And then
    choose what works easiest for them. :)

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Aug 3, 2007
    #5
  6. Thanks alot for hints.. The HDR alignment tool works great for me! Just what
    I was looking for!

    Pete
     
    Jar Jar Binks, Aug 6, 2007
    #6
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