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Could someone please help me with creating a workflow stitching together aerial photos shot vertically down (nadir) into a long photograph (several kilometers). I'm using the 'multiple viewpoints' function and setting the focal length to 1000mm as suggested in previous posts but the resulting image is still distorted. Is spherical projection the best for this? I'd imagine a similiar application to be photographing a long wall, or while walking along a street to capture the side of a city block. Any other tips and tricks for this application would be greatly appreciated. Thanks!
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ekisfaludy wrote:
but the resulting image is still distorted. Is spherical projection the best for this?
You mean the stitch-result is distorted spherically? Which projection did you select?
Can you show all of your settings for the stiching/editing?
best, Klaus
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[img]http://www.flickr.com/photos/88823122@N03/8312440510/
[img]http://www.flickr.com/photos/88823122@N03/8311389447/
[img]http://www.flickr.com/photos/88823122@N03/8311389355/
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Did these links work? I do not know how to post images in forums very well.
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ekisfaludy wrote:
Did these links work? I do not know how to post images in forums very well.
As default projection you have "spherical" - could you try "automatic" or "planar"?
best, Klaus
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ekisfaludy wrote:
Did these links work? I do not know how to post images in forums very well.
If you use Post reply (you'll find it right side below Quote), you will find an image upload facility below the message composition box
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I found a post where 1000mm is suggested to be applicable for art work, for aerial work 100.000mm did give better results:
http://www.kolor.com/forum/t12895-creat … aerophotos
spherical projection... depends on your images. if you have images like in autopano aerial case are used than yes (spherical):
http://www.autopano.net/wiki-en/action/ … ial_photos
and the final result:
http://web.visuel3d.com/Oisans/Oisans.html
if they are rather shot from above to bottom like in first link I would use as Klaus did suggest...
Georg
Last edited by gkaefer (2012-12-27 12:26:18)
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Thanks guys, I'll try these suggestions. In the meantime, I'm trying to make a flat map of the ground using vertically shot images and just want to be sure all my settings are set up correctly. Any unique tips and tricks with settings would be appreciated in addition to the good ideas Salzburg suggested above.
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Panoramic stitching algorithms assume a camera at a fixed location taking images at different orientations. What I, and I guess ekisfaludy, would like to do is the opposite of this, namely the camera has a fixed orientation (vertically downwards in this case) but the images are captured at different locations. I am stitching together multiple images of large historic maps using a high resolution camera on an overhead rail. This is the same situation as an aircraft taking aerial photos from a constant height. In both cases the end result is a flat image made up of a mosaic of approximately flat images. The undulations of the parchment of the historic map produce local non-linear distortions in the same way that variations in ground elevation do for vertical aerial photography. The SIFT algorithm should be able to match up high contrast features in overlapping images to produce an acceptable end result by optimising a non-linear warping of each adjacent pair of overlapping images while retaining the overall planar geometry of a true vertical projection. What I don’t know is whether there is something fundamental in the mathematics behind the SIFT algorithm that assumes a fixed camera location. The best that I have been able to come up with is to force the focal length of the camera to its maximum possible value which seems to be 10,000 mm (10 meters) for autopano giga so that the spherical projection approximates to a flat surface. If the software could be coded so that the maximum focal length is closer to infinity, say 100,000 mm, then we would have what we wanted to within a pixel of a flat vertical projection. I’ve asked this same question to the technical inquiry so will be interested in the result. Has anyone else any insights or suggestions?
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lovelace wrote:
Panoramic stitching algorithms assume a camera at a fixed location taking images at different orientations. What I, and I guess ekisfaludy, would like to do is the opposite of this, namely the camera has a fixed orientation (vertically downwards in this case) but the images are captured at different locations. I am stitching together multiple images of large historic maps using a high resolution camera on an overhead rail. This is the same situation as an aircraft taking aerial photos from a constant height. In both cases the end result is a flat image made up of a mosaic of approximately flat images. The undulations of the parchment of the historic map produce local non-linear distortions in the same way that variations in ground elevation do for vertical aerial photography. The SIFT algorithm should be able to match up high contrast features in overlapping images to produce an acceptable end result by optimising a non-linear warping of each adjacent pair of overlapping images while retaining the overall planar geometry of a true vertical projection. What I don’t know is whether there is something fundamental in the mathematics behind the SIFT algorithm that assumes a fixed camera location. The best that I have been able to come up with is to force the focal length of the camera to its maximum possible value which seems to be 10,000 mm (10 meters) for autopano giga so that the spherical projection approximates to a flat surface. If the software could be coded so that the maximum focal length is closer to infinity, say 100,000 mm, then we would have what we wanted to within a pixel of a flat vertical projection. I’ve asked this same question to the technical inquiry so will be interested in the result. Has anyone else any insights or suggestions?
apg 3.0.1 - it depends from sensor factor. in my example I did change the exif manually to claim to be from Canon EOS 5D Mark III, with sensor factor 1.0.
the resulting focal (35mm equiv) can be set to up to 999999.99. if you use a crop sensoor than the imput focal is accordingly smaller...
Georg
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Thanks Georg, that is very interesting. This seems to solve the problem of producing true planar stitching (or at least infinitesimally close to it). This is a problem whose solution has remained elusive for many years! One question though - do I change the EXIF data on each image before importing in APG or will the image settings dialog you show override the EXIF data for me within APG? I’m still a novice as I've only been using APG for a few days (still waiting for my licence to come through so using the trial version). David
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lovelace wrote:
Thanks Georg, that is very interesting. This seems to solve the problem of producing true planar stitching (or at least infinitesimally close to it). This is a problem whose solution has remained elusive for many years! One question though - do I change the EXIF data on each image before importing in APG or will the image settings dialog you show override the EXIF data for me within APG? I’m still a novice as I've only been using APG for a few days (still waiting for my licence to come through so using the trial version). David
I did it from inside apg. (the images used even were not 5D Mark II images, they are originally a Canon S95 with sensor scale of 4.6.
So it depends on workflow & number of images. I dont wanna change 500 images in APG's image properties 
Here I would prefer it preprocessing them with EXIF Tool Gui, EXIF Pilot or any other tool...
Georg
PS License & waiting - go to www.kolor.com -> click on "my account" -> login ->click on "My Licenses" : now you should see your licesnes .... you can copy&paste them to register your version. if no license is listed and you did pay with creditcard... I would contact via phone or via email kolor staff directly....
Last edited by gkaefer (2013-01-02 13:40:15)
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I will use Exiftool to change the focal length on the image files since I have many 100's of images and many maps to stitch so I'll create a batch file.
Somewhat off topic but since you mention it:
I can't use my shiny new tools because when I bought APG and PTP (31st Dec) I inadvertantly typed my email address wrongly (by one character) so I'm not recognised by Kolor's customer database. I'll only know this because a staff member sent me a screen shot of my account details at 8.20 am this morning which shows the erroneous email address. This is no help because any password gets sent to this erroneous address and into oblivion. All this morning I have been trying to contact Kolor to explain the problem so they can change the email on the database but I've had no response at all and cannot find any telephone number on their website. Do your happen to know it? Thanks David
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lovelace wrote:
I will use Exiftool to change the focal length on the image files since I have many 100's of images and many maps to stitch so I'll create a batch file.
Somewhat off topic but since you mention it:
I can't use my shiny new tools because when I bought APG and PTP (31st Dec) I inadvertantly typed my email address wrongly (by one character) so I'm not recognised by Kolor's customer database. I'll only know this because a staff member sent me a screen shot of my account details at 8.20 am this morning which shows the erroneous email address. This is no help because any password gets sent to this erroneous address and into oblivion. All this morning I have been trying to contact Kolor to explain the problem so they can change the email on the database but I've had no response at all and cannot find any telephone number on their website. Do your happen to know it? Thanks David
Hi David,
on bottom of following press release, I expect the press departments phone number...
http://www.kolor.com/images/stories/pre … o-3-en.pdf
maybe webform may be better/faster for support issues:
http://www.kolor.com/contact.html
Georg
Last edited by gkaefer (2013-01-02 14:41:21)
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Off topic: This is a most informative and inspiring forum and Kolor staff have been most helpful with my account and registration problems which have now been resolved.
For future reference: the email you enter when buying becomes your license user name and can never be changed.
Because I put in the wrong email at the beginning and that has since been changed on the customer database I still must use the one I entered to register the software.
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I tried mediavets solution but it still doesn't seem to work fine. Anything that I might have skipped?
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