| Author |
Message |
    
Russell McBride
New member
Username: Russellmcbride
Post Number: 1
Registered: 11-2003
| | Posted on Tuesday, November 11, 2003 - 2:03 pm: |   |
I am trying to stitch the follwing pano together. I used a 16-35mm Canon Zoom @ 16mm mounted on a Canon 1Ds (full frame digital camera). I had the camera set to manual and used the same exposure for all images.
I let pano factory choose the right lens, correct brightness, and distortions, and automatically fine tune. Also, I tried it with me selecting the focal length, fine tuning, and automatic corrections turned off with the same failing results.
I know the problem is in my technique somewhere; I just don't know where.
I did use my camera mounted on a tripod with a normal ball head.
The link provided shows the final output image with no cropping or any manual adjustments made.
http://www.russellmcbride.com/temp/final_image.jpg
I guess my biggest question is; is the reason this image did not stitch properly because I did not use a pano head and rotate the lens on the nodial point? If not then what do I need to do to get the best stitch? I'd much rather do the work before I press the shutter button than later on the computer if that makes a difference.
Thanks in advance,
Russell McBride |
John Strait
Moderator
Username: Jstrait
Post Number: 32
Registered: 5-2001
| | Posted on Tuesday, November 11, 2003 - 5:15 pm: | |
Focal length
The first thing is that the focal length setting is incorrect. This is most evident in the foreground areas of the boardwalk. The lines of the boards do not match smoothly. In this case, the mismatches indicate that the focal length setting was too large.
You didn't say whether you selected Automatically detect focal length for this picture. If you chose the focal length value yourself, then maybe the automatic detection might find a better value. Sometimes the best focal length setting is a little different from what is printed on your lens.
If the automatic focal length detection doesn't give a good result, then you need to manually adjust the focal length setting. The help page Adjusting focal length and barrel correction gives step-by-step instructions and also shows how to judge whether the focal length is too large or too small.
It is very important to have the correct focal length setting. Nothing will work right when the focal length is wrong. For example, incorrect focal length settings cause ghosting that cannot be fixed except by correcting the focal length. The ghosts in the suspension cables on the left hand bridge are almost certainly caused by the incorrect focal length setting.
Nodal point
Some of the ghosting in this image probably comes from the fact that the camera was not rotated around its nodal point. Nodal point misalignment is usually responsible if foreground objects match properly but background objects at the same horizontal position do not (or the reverse). You can see this effect in the right most bridge pillar where the foreground railing matches correctly.
When a panorama contains foreground and background objects that are close together, there may not be any way to stitch correctly if the nodal point is not aligned properly. See Setting up your camera for more information.
Other ghosting
After adjusting the image-to-image alignment, The Panorama Factory performs an alignment "fine tuning" procedure. It divides the overlap region into small areas and makes local adjustments to the alignment. This normally helps improve the alignment and reduce the appearance of ghosts (local misalignments).
For some images, however, the fine tuning can cause problems. When an area of the image has very little detail (e.g. flat blue sky) or moving objects (e.g. clouds that move in the time between exposures), the automatic fine tuning can produce poor results.
To correct this type of problem, you must manually edit the fine tuning. One option is to remove the fine tuning from the sky, allowing the clouds to be misaligned. This is not usually a problem--misalignments in clouds are often unnoticeable in the finished picture.
To learn about how to manually the fine tuning, read the help page Fine tuning the image alignment. In fact, there is an image in this help page that shows an example of how cloud motion can confuse the automatic fine tuning. See the pictures in the section "Judging the fine tuning."
You may also find it helpful to read the article A fine tuning challenge for a more detailed explanation of alignment fine tuning.
I hope this helps! |
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