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Author Topic: Converting my parameters in px to mm  (Read 5391 times)

Bapt

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Converting my parameters in px to mm
« on: March 19, 2015, 11:07:23 AM »
  Hello,

  I use Agisoft Lens to calibrate my camera.
Nevertheless, I have results in px and I want them in mm.
How can I do it?

Alexey Pasumansky

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Re: Converting my parameters in px to mm
« Reply #1 on: March 19, 2015, 05:42:35 PM »
Hello Bapt,

The camera model is described in Appendix C of PhotoScan manual.

Also you can save calibration results in other from .xml formats (like CalCam or PhotoModeller formats) in case they are more convenient to you.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Bapt

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Re: Converting my parameters in px to mm
« Reply #2 on: March 19, 2015, 05:50:26 PM »
  Yes, I know this.
Nevertheless, to save my project in PhotoModeler format for instance, I need my parameters in mm like my focal length.

Alexey Pasumansky

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Re: Converting my parameters in px to mm
« Reply #3 on: March 19, 2015, 06:02:05 PM »
Hello Bapt,

To convert focal length and principle point coordinates from pixels to mm you still need to know sensor pixel size:

focal_length (mm) = focal_length (pix) * sensor_pixel_size (mm/pix)
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Bapt

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Re: Converting my parameters in px to mm
« Reply #4 on: March 20, 2015, 10:55:58 AM »
  I thank you for your answer.
And, for these parameters what are the formulas to convert px in mm?
  -Format width
  -Format height
  -Principal point X
  -Principal point Y

Alexey Pasumansky

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Re: Converting my parameters in px to mm
« Reply #5 on: March 23, 2015, 08:19:08 PM »
Hello Bapt,

To convert these parameters from pixels to mm you also need to multiply pixel values on pixel size (in mm/pix).
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Bapt

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Re: Converting my parameters in px to mm
« Reply #6 on: March 24, 2015, 07:07:36 PM »
  Hello Alexey,

  So, I calculate them like this :
  Principal_point (mm) = Principal_point (px) * sensor_pixel_size (mm/px)

  Moreover, what are the units of K1, K2, K3, P1 and P3?
  And, do I need to transform them also to save my project to PhotoModeler format?
 

Alexey Pasumansky

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Re: Converting my parameters in px to mm
« Reply #7 on: March 24, 2015, 07:11:50 PM »
Hello Bapt,

The formulas for the distortion parameters are given in the Appendix C of PhotoScan Manual, and there's no straightforward conversion between distortion models used in different packages.

If you need them in PhotoModeler format, then you need to save calibration in XML format in Agisoft Lens and use PhotoScan to convert it to the desired format via Tools Menu -> Camera Calibration window.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Bapt

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Re: Converting my parameters in px to mm
« Reply #8 on: March 25, 2015, 01:27:28 PM »
  Hello Alexey,

  Unfortunately, I don't have PhotoScan.
Can you do it for me if I send to you the file .XML?

Alexey Pasumansky

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Re: Converting my parameters in px to mm
« Reply #9 on: March 25, 2015, 01:29:35 PM »
Hello Bapt,

You can use a 30-day Trial for PhotoScan Pro:
http://www.agisoft.com/downloads/request-trial/

But if you wish, you can send an xml to support@agisoft.com.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

Bapt

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Re: Converting my parameters in px to mm
« Reply #10 on: March 25, 2015, 04:18:01 PM »
  I sent a mail.
  I thank you again.