Agisoft Metashape

Agisoft Metashape => Camera Calibration => Topic started by: Bapt on March 19, 2015, 11:07:23 AM

Title: Converting my parameters in px to mm
Post by: Bapt 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?

Title: Re: Converting my parameters in px to mm
Post by: Alexey Pasumansky 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.

Title: Re: Converting my parameters in px to mm
Post by: Bapt 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.

Title: Re: Converting my parameters in px to mm
Post by: Alexey Pasumansky 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)

Title: Re: Converting my parameters in px to mm
Post by: Bapt 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

Title: Re: Converting my parameters in px to mm
Post by: Alexey Pasumansky 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).

Title: Re: Converting my parameters in px to mm
Post by: Bapt 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?
 

Title: Re: Converting my parameters in px to mm
Post by: Alexey Pasumansky 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.

Title: Re: Converting my parameters in px to mm
Post by: Bapt 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?

Title: Re: Converting my parameters in px to mm
Post by: Alexey Pasumansky 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.

Title: Re: Converting my parameters in px to mm
Post by: Bapt on March 25, 2015, 04:18:01 PM

  I sent a mail.
  I thank you again.