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Stitching - too much overlap?

Apr 10, 2012 7:41 AM

I can't get stitching to work in this case. Is there too much overlap? Too many Images?

Images doo not align well, and are not merged correctly.

stitching.jpg

 
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  • Noel Carboni
    23,482 posts
    Dec 23, 2006
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    Apr 10, 2012 7:46 AM   in reply to ingvarai

    I suspect the problem may be that you shot through a window and the reflections are confusing Photomerge.  Or am I misinterpreting what I'm seeing?

     

    Normally, with clean exposures, it gets things right to the very pixel.

     

    -Noel

     
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  • Noel Carboni
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    Dec 23, 2006
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    Apr 10, 2012 8:13 AM   in reply to ingvarai

    OK, so what I perceived as reflections are really radical differences in exposure.

     

    I'm thinking maybe that's the problem - the individual frames are just too far apart in exposure, and possibly color-balance.

     

    Did you shoot raw?  If so, you could consider dragging all the images into Photoshop so they open in Camera Raw, then normalizing the exposures by hand (e.g., using the Exposure slider).  When done, save all the images as PSD files, then run the Photomerge on those.

     

    -Noel

     
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  • Noel Carboni
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    Dec 23, 2006
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    Apr 10, 2012 8:47 AM   in reply to ingvarai

    In that case I wonder if it could have been a resource shortage that stopped it from completing the big image.

     

    Anyway, it's good you found a workaround.

     

    -Noel

     
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    Apr 10, 2012 9:36 AM   in reply to ingvarai

    I think the problem here is parallax error.

     

    With shots like this you really need to rotate the camera strictly around the optical center of the lens - not the camera screw mount, and certainly not handheld. Use a tripod with a pano head, which allows you to retract the camera along a rail and lock the position. If you need up and down as well it can get tricky.

     

    The optical center is where the diaphragm appears to be when you look into the lens from the front. Of course that's not where it really is...

     

    (What's the final pixel size of this thing? I'm gearing up for an interesting assignment I just got, billboards at high resolution, that will end up at around 10 000 x 15 000 pixels. I need to make 20 of these, using, it seems, my 12 mp Nikon. I have a digital back on order, but it won't arrive in time. So I have a lot of stitching ahead...)

     
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  • Noel Carboni
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    Dec 23, 2006
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    Apr 10, 2012 10:05 AM   in reply to ingvarai

    I have seen big Photomerge operations chew up more than 200 GB (yes, that's gigabytes) of space on the scratch drive.  I'm betting doing the whole thing at lower resolution is going to work for you.

     

    -Noel

     
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    Apr 10, 2012 11:49 AM   in reply to ingvarai

    ingvarai wrote:

     

    I have had no problems with handheld and stitching.

    Well, maybe so, but there is some funny stuff going on with the roof tiles in the foreground if you look closely. Even if it won't stop the process, it's still good practice to try to minimize parallax errors. I'm not making this up: http://en.wikipedia.org/wiki/Parallax

     

    The further away everything is, the less it matters. It's when you get things close that a small camera movement can throw alignment completely off.

     
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