Messages

1

General / Re: What units PS use for distortion parameters?

« on: June 16, 2011, 05:45:03 PM »

Hi,

thanks for answer, you are right about units, but there is one more thing to be mentioned.
PS uses opposite sign for k1, ..., p1 values.
I have tried to compare distorition results from PS and PhotoModeler. They seem pretty simmilar, but the signs are inverted.
I have been looking for answer. PS has differen definition of distortion values than is usual.
PS:
http://www.agisoft.ru/lens/help/en/lens.pdf (last page)
and usual definition from wikipedia:
http://en.wikipedia.org/wiki/Radial_distortion
Usualy distorition values are defined in direction from distorted image to undistorted image.

Regards
Bronislav

2

General / Re: What units PS use for distortion parameters?

« on: June 12, 2011, 11:44:28 PM »

Hi,
thanks for quick answer, but Im pretty sure you are wrong about units.
As I wrote before it uses pixel for fx, fy, cx, cy but k1, k2, k3 , p1, p2 have different units.
I know it because its value are very big (usually about 1e-2) to be in mm or pixels.
May be they are in pixels internally but they used some constant to multiply its value before showing it/export/import.
Any other idea?
B.

3

General / What units PS use for distortion parameters?

« on: June 12, 2011, 07:36:49 PM »

Hi,
I have a guestion, what units use PS for distortion parameters.
More preciselly, what units are used for radial and tangencial distortion parameters because it seems clear fx, fy, cx, cy are stated in pixels.

For k1, .., k3 are usually use (mm^-2,mm^-4,mm^-6) or (pixel^-2,pixel^-4,pixel^-6) but it is not the case of PS.
I would like to use calibration parameters from PhotoModeler (where mm are used) and I'm not sure about conversion.
Thanks
B. Koska