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Author Topic: Principal Point Coordinates  (Read 5183 times)

n@sk

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Principal Point Coordinates
« on: September 06, 2016, 08:30:35 PM »
Hello,

I noticed that the Principal Point in the Camera Calibration menu (v1.2.6 b2834) is not reported in pixels like I would expect looking at calibration xml exports from older versions (~[imageSize/2]).

It looks like the values are either in the camera coordinate system or just the offsets in pixels,
which means that exports from Lens are going to cause problems?

I checked the changelog and the 'camera model modification' in v1.2.4 looks suspicious  :)

Could you please let me know if I am missing something?


Thanks

Alexey Pasumansky

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Re: Principal Point Coordinates
« Reply #1 on: September 07, 2016, 11:45:50 AM »
In the older versions Cx and Cy were given in pixels from the top-left corner of the image, in the latest release version they are measured as offset from the image center, but we have added backward compatibility, so the older XML files with the calibration can be properly loaded to the latest release.
Best regards,
Alexey Pasumansky,
Agisoft LLC

n@sk

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Re: Principal Point Coordinates
« Reply #2 on: September 07, 2016, 02:41:59 PM »
Thanks Alexey,

I guess the habit of typing values manually is not backwards compatible  :D

Alexey Pasumansky

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Re: Principal Point Coordinates
« Reply #3 on: September 07, 2016, 04:01:20 PM »
Hello n@sk,

But you can type in values to the XML file in the older format and load it, it may save you some time, as you do not need to subtract the image half-height  and half-width.

Also as far as I remember, the meaning of P1 and P2 parameters has been swapped, so please also pay attention to it.
Best regards,
Alexey Pasumansky,
Agisoft LLC

n@sk

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Re: Principal Point Coordinates
« Reply #4 on: September 25, 2016, 03:10:14 AM »
Hi Alexey,

thanks for the heads up about p1&p2, I will definitely stop typing values manually...
The camera model in the current manual seems similar to Australis which is nice.

However, have you tested this with Lens?
The conversion from Australis stores values as Principal Point coords and not  corrections so I still get w/2,h/2 in a new format xml which loads as is in PS.

thanks

Alexey Pasumansky

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Re: Principal Point Coordinates
« Reply #5 on: September 26, 2016, 06:20:12 PM »
Hello n@sk,

Can you send the LNZ project file to support@agisoft.com for the further investigation of the problem?
Best regards,
Alexey Pasumansky,
Agisoft LLC

Alexey Pasumansky

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Re: Principal Point Coordinates
« Reply #6 on: September 27, 2016, 09:00:14 PM »
Hello n@sk,

Thank you for providing the data, we were able to reproduce the issue and find the source of it, so the fix will be included in the next update.
Best regards,
Alexey Pasumansky,
Agisoft LLC