free SW for Transverse Mercator projections?

[RobA]

Based on your other post, I think what you want is to go from an image like this (equirectangular):



to this:



I did this using Gimp, with the mathmap plugin, using the following mathmap script I wrote:

unit filter sinusoidal (unit stretched image in)
    divs = 9;
    py = 2;
    counter = 0;
    while (counter <= divs) do
      px = if (x>1-(2*counter/divs)-1/divs && x<=1-(2*counter/divs)+1/divs) 
           then (x-(1-(2*counter/divs)))/cos(y*pi)+1-(2*counter/divs)
           end;
      py = if (x>1-(2*counter/divs)-1/divs && x<=1-(2*counter/divs)+1/divs &&
               px<=1-(2*counter/divs)+1/divs  && px>=1-(2*counter/divs)-1/divs)
           then y
           else py
           end;
      counter = counter + 1;
    end;
    in(xy:[px,py])
end

Change the divs=9 to however many "petals" you want.

edit: Another thing tha might make this easier to assemble is what i did in the next one. I offset bottom half of the image by 1/2 the petal width (in this case 60 px), ran the filter, then offset the bottom half back (-60px), with wrap on, of course.:



-Rob A>