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Author Topic: Tie Points definition  (Read 8589 times)

AntonBlumenstein

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Tie Points definition
« on: June 07, 2018, 04:17:03 PM »
Hey guys,

I read the user manual of Photoscan and cant still figure out what the Tie points in the allginment step are ?

Could someone explain what they are doing, is it just a filtering methode of bad points?


Cheers!!!

AntonBlumenstein

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Re: Tie Points definition
« Reply #1 on: June 11, 2018, 06:59:06 PM »
no one?

Yoann Courtois

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Re: Tie Points definition
« Reply #2 on: June 12, 2018, 10:44:47 AM »
Hi Anton !

"Tie points" are actually matches between SIFT points (named "key points") detected on two (or more) different images.
They are the link between images to get 3D relative positioning !
Those points can be filtered, using different methods (Gradual selection tools in PhotoScan) in order to converge to a more precise relative orientation.
On picture overview panel, after the alignment step done, blue points are valid tie points used to get this 3D relative orientation, whereas grey points are disabled tie points, disabled because of their imprecision.
Most of the time, just a few points are directly disabled by PhotoScan, but you can get a better result using some well-employed filters.
Nevertheless, at first, trusting PhotoScan algorithms already give you great results if you import a good set of pictures

Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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AntonBlumenstein

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Re: Tie Points definition
« Reply #3 on: June 17, 2018, 01:34:26 PM »
Thank you very much Yoann.
I Think I understood the difference now :)


Cheers!