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Correct barrel distorion before stitc...

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Edward Rotberg
Posted on Saturday, November 17, 2001 - 12:20 pm:   Edit PostDelete Post

I have a Nikon Coolpix 995, and with the standard lens, there is considerable barrel distortion. It is possible to correct this distortion in Photoshop in each image prior to stichting. I would think that stitching undistorted images (or less distorted images) would yield superior results. However, since you now have specific lens settings for the Nikon 995, is it detrimental to correct this distortion?
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John Strait
Posted on Saturday, November 17, 2001 - 12:27 pm:   Edit PostDelete Post

The Panorama Factory does not have a specific correction for barrel distortion. If it is possible to use another image processing program such as PhotoShop to correct it before running The Panorama Factory, this will probably produce better results.

Just be sure that all images are processed in a consistent manner.
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Edward Rotberg
Posted on Saturday, March 09, 2002 - 11:53 am:   Edit PostDelete Post

John,

I finally got around to testing this out. It is DEFINITELY worth correcting barrel distortion before stitching with Panorama Factory. The results I have been getting since correcting for BD have required absolutely no manual adjustments and look perfect - Better than the ones that I had manually adjusted.

It might be worth looking into incorporating some option to pre-correct each image for barrel distortion in the program at some future date. I was just amazed at how much better the results are with the same source images after pre-correcting. :-)

= Ed =
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Jeff Epler
Posted on Tuesday, October 15, 2002 - 8:54 pm:   Edit PostDelete Post

It'd be especially nice if Panorama Factory did barrel distortion correction with the rest of the stitching process for two reasons.

First, for all the same reasons that it's desirable to "improve quality", it would be good to calculate barrel distortion along with all other parameters in one step (reportedly, this is done by PanoTools)

Second, I don't have any software that will debarrelize a 48-bit TIFF file (converted from my Nikon 5700's 36-bit RAW mode) so I am forced to choose between losing the larger colorspace or having barrel-corrected input images.
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John Strait
Posted on Monday, October 21, 2002 - 9:11 am:   Edit PostDelete Post

Correction for barrel distortion will be in the next major release of the software. Unfortunately, I am unable to give a release date at this time.
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John Strait
Moderator
Username: Jstrait

Post Number: 24
Registered: 5-2001
Posted on Monday, November 03, 2003 - 3:11 pm:   Edit PostDelete Post

Correction for barrel distortion was introduced in the V3 release of The Panorama Factory. This means that there is no longer a need to correct the barrel distortion using another application. Instead, you should enable the correction for barrel distortion on Wizard step 2.
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Wayne Parnin
New member
Username: Waynep

Post Number: 1
Registered: 11-2003
Posted on Thursday, November 13, 2003 - 7:27 pm:   Edit PostDelete Post

Is there a limit to the amount of barrel distortion PF can handle? I use a 0.5x convertor on my digital camera and the result is pretty severe distortion. I am able to use an image editor (PaintShop Pro 8.0) to correct the distortion and the resulting images stitch beautifully in PF, but PF's built-in correction can't deal with the "raw" images.

Using PSP isn't really much of a hardship, but it would be more convenient to do it "all" in PF.

Thanks
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John Strait
Moderator
Username: Jstrait

Post Number: 33
Registered: 5-2001
Posted on Friday, November 14, 2003 - 10:14 am:   Edit PostDelete Post

Hi Wayne,

There are two limits in The Panorama Factory one the correction of barrel distortion.

Manual entry of the correction factor for barrel distortion correction is limited to values in the range -100% (barrel distortion) to +100% (pincushion distortion). In practice, this is not a significant limitation because 100% is much larger than you will ever encounter with any lens. See Correct barrel distortion for an illustration of 10% barrel distortion.

The second limit is on the automatic detection of barrel distortion, which is limited to a range of -6.3% to +6.3%. This range covers most lenses but may be insufficient to correct extreme barrel distortion exhibited by certain lenses.

The automatic range limits were set this way to to deliver reasonable performance while handling most situations. Detecting the barrel correction value is compute-intensive, and increasing the range would hurt performance for the average user.

Your 0.5x converter exhibits a much larger degree of barrel distortion. I measured it at approximately -18.5% (thanks for sending sample photos). For a lens with this much barrel distortion, you'll need to manually enter the barrel correction on the Camera properties dialog box or through the procedure for manually adjusting the barrel correction that is described at Adjusting focal length and barrel correction.

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