Agisoft Metashape

Agisoft Metashape => Camera Calibration => Topic started by: Ludwig Hilger on April 17, 2013, 08:46:37 PM

Title: Getting k1, k2, k3 from distortion table?
Post by: Ludwig Hilger on April 17, 2013, 08:46:37 PM
Hello everybody,

I have a Sony NEX-5 with a fixed 16 mm lens. I got it calibrated in a laboratory and got a report with all the parameters (fx, fy, cx, cy) in mm (so I converted them in pixels and I get numbers similar to the ones estimated by PhotoscanProfessional, difference in fx, for example is about 30 pixels). The report also has a radial symmetric lens distortion table. As I am a photogrammetry beginner I am wondering if I can convert the values in the table to the k1, k2, k3 parameters to use in Photoscan Professional.

Any help is very much appreciated,

regards,
Ludwig
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Alexey Pasumansky on April 17, 2013, 10:29:16 PM
Hello Ludwig,

Could you please specify the software used for camera calibration? And please also share the calibration parameters acquired by it.
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Ludwig Hilger on April 18, 2013, 09:16:24 PM
Hello,

thanks for your reaction! Actually I do not know the software, I just got an Excelsheet with the results on it. If it could helop I could certainly ask for the software used. The parameters I got are:
Focal length: 16.409 mm
Chip format x: 24,260 mm
Chip format x: 13,603 mm
Pixel size (x,y): 5.282 mum
Principal Point: 12.055 mm (x), 6.870 mm (y)

The coordinates refer to a coordinate system with the origin at lower left (x positive to the left, y positive to the top)

Radial Symmetric Lens Distortion:
R (mm)                      Delta R (mum)
0                               0
2.5                            27
5                               26
7.5                            9
10                             1
12.5                          46
15                             205

Thank you again,

Ludwig
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Alexey Pasumansky on April 19, 2013, 01:08:32 PM
Hello Ludwig,

If it's possible it would be much better to know the calibration software used, so we will have the information about distortion model used there, otherwise any our assumptions regarding conversion to Lens/PhotoScan calibration will be unreliable.
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Ludwig Hilger on April 22, 2013, 03:03:32 PM
Hello,
thank you again for your effort. I now got the information that the values were computed with a program called "Bingo". Can that help me?

thank you!
Ludwig
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Alexey Pasumansky on May 08, 2013, 02:59:48 AM
Hello Ludwig,

Sorry for the late reply, but unfortunately it is not possible to import/convert camera calibration based on the table values.
The only solution we can suggest at the moment is try to convert this calibration to one of the formats supported by Lens for conversion (iWitness, Photomodeler, CalCam).
Title: Re: Getting k1, k2, k3 from distortion table?
Post by: Ansari443 on October 09, 2014, 10:23:19 PM
Hello,

Could you provide any Topcon Imagemaster Photo calibration specifications regarding the distortion model used?