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Author Topic: calibration p1 p2  (Read 3430 times)

hagorms

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calibration p1 p2
« on: March 23, 2018, 01:19:43 PM »
Hello.
I try to precalibrate cameras using other software and I think I found a bug.
After I define calibration as it is shown in the picture below in the gui I set p1 = 7 and p2 = 8, but when I export cameras it gives me :
<p1>8</p1>
 <p2>7</p2>
 <p3>9</p3>
  <p4>10</p4>

Alexey Pasumansky

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Re: calibration p1 p2
« Reply #1 on: March 23, 2018, 01:51:42 PM »
Hello hagorms,

When you import the XML back, do you get the same order as before?

At some point the meaning (order) of the coefficients in PhotoScan has been changed, but for backward compatibility, the labels of the coefficients remain the same.
Best regards,
Alexey Pasumansky,
Agisoft LLC

hagorms

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Re: calibration p1 p2
« Reply #2 on: March 23, 2018, 01:54:18 PM »
Yes, they  stay the same after importing xml back.
I think you just forgot to change labels in GUI

Alexey Pasumansky

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Re: calibration p1 p2
« Reply #3 on: March 23, 2018, 02:00:02 PM »
Hello hagorms,

If we change the labels in GUI, the coefficients will no longer fit the distortion model formulas from Appendix C of PhotoScan manual.
Best regards,
Alexey Pasumansky,
Agisoft LLC

hagorms

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Re: calibration p1 p2
« Reply #4 on: March 23, 2018, 02:03:01 PM »
so change them in xml. 
Your xml file and gui have different names for same values.
Let's say after I calibrate my camera I have p1 = 0.001 and p2 = 0.003. If I load them through GUI and through XML, i will have different callibrations. 

n@sk

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Re: calibration p1 p2
« Reply #5 on: April 13, 2018, 08:30:04 AM »
Hi hagorms,

this reminds of a similar thread I started a couple of years ago
http://www.agisoft.com/forum/index.php?topic=5827.msg28767#msg28767
The conclusion then, was to use PhotoScan in order to convert the values assuming that you are using Australis, PhotoModeler etc for the calibration.
The tag in the GUI and the appendix is the correct one but you should NOT manually edit the value with the same tag in an xml which was created with the latest versions.
I suppose that Alexey would be happy to implement a new conversion if you are using another application but this is indeed a mess...

Alexey,
Is backwards compatibility still a valid issue?
If yes, then you should consider flipping this behaviour or make it more transparent.
I would expect a notification similar to the bundler.out export.

regards