Hallöchen! Okay, now for the definitive, thoroughly calculated solution. Sorry for the confusion.
Helmut Jarausch writes: > [...] > > - using Octave I fitted a polynomial of the form > r*(d+r*(c+r*(b+r*a))) to the data using a smoothed maximum norm Let me write this in a different way: r_d = a·r⁴ + b·r³ + c·r² + d·r r: Radius in the undistorted target image r_d: Radius in the distorted original image r is allowed to be scaled; this causes a mere scaling of the result. r_d must not be scaled. If I use e·r instead of r for the look-up, I simply scale down the target image uniformly by the factor e: r_d = a·e⁴·r⁴ + b·e³·r³ + c·e²·r² + d·e·r With the Lensfun+PanoTools constraint d·e = 1 − a·e⁴ − b·e³ − c·e² I have an equation for e. > [...] > > Here are my results: > > The focal lengthes here are scaled by the crop factor > > focal length d c b a > 25 0.997913 0.0213096 -0.102825 0.0261528 Let's take this example. The scaling e is 1.069413355 (solved the above equation numerically, taking the only real solution). Thus the Lensfun coefficients are: a = 0.03420586726 b = -0.1257579729 c = 0.02437061587 If you use this in Lensfun, the correction should work equally well (plus a global uniform scaling of the resulting image). Tschö, Torsten. -- Torsten Bronger Jabber ID: [email protected] ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports. http://sdm.link/zohomanageengine _______________________________________________ Lensfun-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lensfun-users
