Hi
 
I have your command line tool to remove lens distortion from images (Distoma)...
 
I have a few questions -  
 
The distortion value that you enter in - can you tell me exactly what that value is?  My knowledge of photogrammetry tells me that there is a couple of values for distortion, K1, K2, K3 the three co-efficients for radial lens distortion  - i am just wondering where the one wonder figure that Distoma uses comes from!
 
Cheers

Hello,
 
  K1, K2, K3 are the coefs of a polynomial expression.
We consider only the coef of the highest element (in degree) of this polynome.
 
Best,
 
Stef

So should I use one of those values as the IM distortion value, or is there a formula to work out the IM distortion value from these?
 
Thanks

Use the coef K1 or K3 (corresponding to the highest element in degree).
Note that in IM the principal point is always in the middle of the image.
 
Hope it helps,
 
Stef

Thanks for the help!
 
Why out of interest does IM always assume the principle point is in the center of an image?  For instance, a lens I have at home is off by 5 pixels in the Y direction... Surely, assuming this would lead to some big innacuracies in the final photogrammetry solution?
 
Matt