Re: [PanoToolsNG] Re: Reverse distortion correction
- Hi Tim,
> What I have is data sets which produce something like the graph FigureI see, the values are in mm relative to h from centre to top right corner
> 3 (A) on http://www.vanwalree.com/optics/distortion.html
of portrait orientation and expressed in percentage.
> Looking at the Lens Correction Model details onrsrc is the source image and rdest is the destination, the corrected image.
> http://wiki.panotools.org/Lens_correction_model it seems I want to
> convert my data to actual radial distances so rsrc and rdest are
> specified (is src or dest the 'corrected' distance?) rather than a
The radial distance r_src for each point in the source image is computed
by the formula:
r_src = (a * r_dest^3 + b * r_dest^2 + c * r_dest + d) *
Units for r_src and r_dest is image width / 2, ie the edge of the image
corresponds to r_src = 1.
The internal unit used for r_src and r_dest _ is the smaller of the two
image lengths divided by 2.
> I presume I can then take my data and if say rsrc is 35 and rdest 38,You would need to convert your percentages of h in mm to positive or
> I can swap the source and destination and refit the polynomial - will
> this give the the parameters needed to introduce distortion?
negativ pixel distance values of a,b and c and apply the PTcorrect tool
with its reverted values.
I did a short test of a lens correction and reverted a corrected duplicate
with the PTcorrect tool with reverted values (positive to negativ and vice
versa.) overlayed as layers in PS to show the difference. It is perfect,
but cropped by dimensions lost in the original lens correction. PtGui will
do the same with more canvas to play with.
Here is the link to the paper from Prof. Dersch to explain its functions:
Milko K. Amorth
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