I want to build a dome camera lens shader (like the one in vray). So I looked into the domemaster projection and it's supposedly an azimuthal equidistant projection. I found a formula here to convert from lat/long coordinates to x/y values:
http://lazarus.elte.hu/~guszlev/vet/equation/dspostel.htm
q = (PI/2) - latitude
x = q * sin(longitude)
y = q * cos(longitude)
Since x and y are given as a lens shader parameter, I'm interested in the latitude and longitude and thus I want to reverse this formula. However I get stuck when I want to solve for latitude or longitude because it always requires the other angle. Any ideas?
Thanks a lot!
Nhat