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Author Topic: Alignment Video sequence  (Read 8284 times)

7eicher

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Alignment Video sequence
« on: July 06, 2013, 08:34:51 PM »
Hi all together,

maybe this is a silly question, but i didn't found a way in PS to align images by sequence. I have made a video and extracted images, so i know the sequence order and i can specify the image chain. How can i tell PS to match sequencial and not any to any image? Is there a way to do this in a text file like in visualsfm:

imgA.jpg imgB.jpg
imgB.jpg imgC.jpg
...

And aditionaly i would like to start the matching via command line. Is that possible too?

Thanks for your support,

Markus

Wishgranter

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Re: Alignment Video sequence
« Reply #1 on: July 06, 2013, 11:34:52 PM »
if have videosequence tehn you need a bigger difference in frames used, you cannot use every frame. its need a some degree of separation = try to use just every 10-15 image, or better try use images where is few degree movement, so all images are not the "same" or pscan cannot align it correctly... ( Low angle separation ).
 
Can upload it for me ? im have tested even other possibility of mesh extraction from videosequences....
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7eicher

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Re: Alignment Video sequence
« Reply #2 on: July 07, 2013, 12:23:25 AM »
Thanks wishgranter for your reply. I had in mind to use 5 images per second, that i might have 15cm of world distance between each image.

But tell me, if i have hundreds of images, would the alignment process not faster of i would align images sequencial or lets say ordered? As i see PS tries to match each image with each other. If you have 100 images, you might have 99? feature matches. If PS can match only between one and the next frame we would have only 99 feature matches.

On the other side, i guess its worth the time, because the image alignment becomes more accurate.

Wishgranter

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Re: Alignment Video sequence
« Reply #3 on: July 07, 2013, 12:52:04 AM »
just try set in aligning step this settings ACCURACY: MEDIUM and 2nd PAIR PRESELECTION to GENERIC, so it will try detect pairs of iamges, so it will not try align all images to each other, but it select pair wise ( its not a stereo image align, but it work this way :-) ). if OK then set HIGH settings if precisionis not ok...... and let me know.....   
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7eicher

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Re: Alignment Video sequence
« Reply #4 on: July 07, 2013, 01:54:06 AM »
Thanks, that worked out well !!

sarhat

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Re: Alignment Video sequence
« Reply #5 on: July 09, 2013, 07:00:57 PM »
You might use in addition to the separation or by increasing your B/H (base to hight ratio), you can also use Geosetter or any EXIF editor tool to add the focal length of the camera. I have noticed from the tests that using the focal length as an initial value helps reconstruction better

Regards 

7eicher

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Re: Alignment Video sequence
« Reply #6 on: July 09, 2013, 10:57:51 PM »
Thanks sarhat, although i dont have aerial shots i find geosetter a cool tool.

Actually i find the idea of using a video much more efficient for photogrammetry than shooting each image itself. I hope that quality remains. I plan using a 36Mpixel camera with max. 5 images per frame.

I am courious if someone has experience in tools which automatically extract tiff from raw video format. I also wonder if there is software which can detect unsharp images whn using autofocus.

Would be nice if someone shares some of his experience. Greatly appreciated.

Take care

Wishgranter

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Re: Alignment Video sequence
« Reply #7 on: July 09, 2013, 11:25:13 PM »
How many frames can you capture in a burst? Nikon quotes 16, 17 or 20 uncompressed, lossless or compressed RAW files respectively in the 36 Megapixel / 14 bit mode. JPEG shooters can capture up to 56 Large Fine 36 Megapixel JPEGs in a burst, and if you're willing to increase the compression or reduce the resolution, you can increase this to 100 frames. Interestingly like some earlier Nikon DSLRs, the D800 manual states the maximum number of frames in any burst is 100, even if the resolution is lowered, although at 6fps with the battery grip, that'd still take over 16 seconds.

and

I'll give you the results for the D800 first. I started with the UDMA-6 CF card, which allowed me to capture a burst of exactly 100 Large Fine FX-format shots in 24.53 seconds, corresponding to a speed of 4.03fps; the manual quoted 100 shots and indeed the D800 stopped dead at this point, and took a considerable 66 seconds to flush the buffer to the card.

http://www.cameralabs.com/reviews/Nikon_D800/
« Last Edit: July 09, 2013, 11:26:56 PM by Wishgranter »
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7eicher

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Re: Alignment Video sequence
« Reply #8 on: July 10, 2013, 04:20:38 AM »
I read about that article recently too and surely the 66 seconds freeze time isnt really appealing. You take 90 seconds to get max 100 shots full resolution, still not bad.

I listen about Ninja 2 recorder from atomos, sounds like a seamless alternative to SD cards. You can plugin a ssd harddrive and run in full resolution for quite some tim while seeing the result live. Off course that works not with all cameras today, oly those with hdmi out.

About nikon d800 some complain aboit moire effects in video mode, can someone confirm that?