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Thread: Panorama Stitching Challenge

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joe r

Posts: 14
Location: United States
Registered: 19 Feb 2013
Panorama Stitching Challenge
Posted: 19 Feb 2013 at 1:23 GMT
updated: 19 Feb 2013 at 1:43 GMT
This 8-shot panorama features telephone lines that are not stitching correctly in Photoshop CS6 or PTGui 9 with the standard software settings:


The images were shot with an 18mm Olympus lens mounted vertically on a 5D Mark II. The camera was on a nodal slide, but the setting was incorrect. Here is a folder with a zip file that has 2000x3000 jpeg versions of all 8 images (33MB): dl.dropbox.com/u/106817539/pano_challenge.zip

Do you have a good panorama stitching technique for correcting parallax error in long sections of telephone wires? The warp tool and masking in Photoshop is too tedious. There has to be a better way.

Thanks for taking the time to give this stitch a try -- I'll be curious to see if anyone has a good way to fix the wires!
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John Houghton

Posts: 3935
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: Panorama Stitching Challenge
Posted: 19 Feb 2013 at 9:19 GMT
Joe, Overhead wires are seldom completely stationary, so alignment may be imperfect due to movement as well as parallax. I tried to align them with straight line control points (type t3,t4... ). Over very short distances, these should work for the gentle curves of the wires in the output panorama image. The alternative Panorama Tools optimizer (PTOptimizer) must be used for this (available for download from the PTGui web site). The result is not quite perfect, but maybe good enough. I've uploaded the project file to:

ge.tt/40H1HrY/v/0

John
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joe r

Posts: 14
Location: United States
Registered: 19 Feb 2013
Re: Panorama Stitching Challenge
Posted: 19 Feb 2013 at 20:19 GMT
Hi John,

Thanks for giving the stitch a go, and for loading the pts file. I'm looking forward to taking a look tonight!

Cheers,

Joe
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joe r

Posts: 14
Location: United States
Registered: 19 Feb 2013
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 4:08 GMT
updated: 20 Feb 2013 at 4:09 GMT
Hi John -

I'm really amazed at the difference between the PTOptimizer and the regular PTGui optimizer with the power lines. The PTOptimizer version is 90% of the way there. A little bit of cloning and it'll be perfect.

Question: How did you decide where to place the straight line control points? Is it a guessing game, or is there a method to the madness?

I really appreciate you taking the time to share this technique!

Joe
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sapper

Posts: 28
Location: Barcelona, Spain
Registered: 23 Jun 2007
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 5:27 GMT
Maybe try this, it's old but.... vicanek.de/plugins/wireworm.htm

good luck,

sapper
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John Houghton

Posts: 3935
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 7:51 GMT

joe r said:

Question: How did you decide where to place the straight line control points? Is it a guessing game, or is there a method to the madness?

The cp's should be positioned on the wires roughly where PTGui will place the seam between the pair of images. After aligning the images with the normal control points, you can make use of PTGui's shadow cursor symbol in the second window. Position the cursor so that the real cursor and its shadow are at the same distance from the inner edges of their respective image frames, i.e. like this:


To get three or 4 points assigned close together in this area, you may need to create the points further apart and then drag them into position, as PTGui doesn't like creating points very close together.

John
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Nick Fan
[NodalNinja]

Posts: 770
Location: Hong Kong
Registered: 26 May 2006
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 9:04 GMT
what do you think of using Puppet War in CS5/6 to fix the wire? Just an idea of its application.

Nick
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John Houghton

Posts: 3935
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 9:59 GMT
Nick, I don't think Puppet Warp would be the tool to use. The technique I use is this: I make a reasonably long thin selection along the wire, starting at the point where the stitching error shows. Copy/Paste, then select Edit->Transform ->Rotate. Move the centre marker over to the other end of the selection (here on the right) and rotate the top image about this point to align at the join. Like this:

Then flatten, and tidy up the join if necessary. This is usually adequate but sometimes I find it helps to do the edit on a crop of the image resized x2 for increased precision to achieve an invisible join.

John
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John Houghton

Posts: 3935
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 11:02 GMT

John Houghton said:

Nick, I don't think Puppet Warp would be the tool to use.

Actually, there's not much difference between the method I described and using Puppet Warp, which I revisited just now. I did find a degree of blurring introduced over the warped area and occasionally some artifacts at the edge of the selected area. Otherwise, the two methods gave similar results.

John
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joe r

Posts: 14
Location: United States
Registered: 19 Feb 2013
Re: Panorama Stitching Challenge
Posted: 20 Feb 2013 at 22:23 GMT
John - Thanks for the extra details on placing the control points. Makes perfect sense.

Nick - Based on a tip from another forum, I've been experimenting with puppet warp. This technique works pretty well for fine tuning the power lines.
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