Converting my parameters in px to mm

[Bapt]

  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]

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.

[Bapt]

  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]

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)

[Bapt]

  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]

Hello Bapt,

To convert these parameters from pixels to mm you also need to multiply pixel values on pixel size (in mm/pix).

[Bapt]

  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]

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.

[Bapt]

  Hello Alexey,

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

[Alexey Pasumansky]

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.

[Bapt]

  I sent a mail.
  I thank you again.