Changes between Version 2 and Version 3 of Help/Plugin/PicLayer
- Oct 10, 2010 10:47:38 PM (3 years ago)
v2 v3 47 47 where b is in degrees, ln ist the natural logarithm and tan ist the tangent. 48 48 The longitude in degrees l is obtained from x via l = x*180/PI. 49 The latitude b can be calculated from y by b = 2*arctan(e **y) - 45 (when inverse tangent returns degrees). 49 The latitude b can be calculated from y by b = 2*arctan(ey) - 45 (when inverse tangent returns degrees). 50 50 When transforming longitude degree differences of image corners to distance, you have to take into account that one degree east-west has different size dependent on latitude. 51 51 At equator 1 degree -> d0 = 111.3 km, at latitude b you get d = d0/cos(b)(only exact for sphere, but deviation from ellipsoid < 0.5%).