Thanks Bob,

My specific question is do the 3dAllineate parameters refer to going from input to base coordinates, base to input, or a combination of the two?



Unless the answer is the last, then my problem is this: using the defaults (so, as you note T = S Y X Z), I'm getting the following results doing the matrix math:

SYXZ = {
{0.9976175704420157, -0.028462533215795813,-0.06284160523339294, 2.0358},
{0.03411788020026907, 0.9952811250128278, 0.09083750571124193, 3.37123},
{0.05995959803075708,-0.0927651141116074, 0.9938810191405462, 24.20178},
{0.0, 0.0, 0.0, 1.0}
}

(SYXZ)inv = Zinv Xinv Yinv Sinv = {
{0.9976175704420157, 0.03411788020026907, 0.05995959803075705, -3.5970980716022245},
{-0.028462533215795807, 0.9952811250128278, -0.09276511411160737, -1.0522966785522614},
{-0.06284160523339294, 0.09083750571124191, 0.9938810191405459, -24.23199095586005},
{0.0, 0.0, 0.0, 1.0}
}

Neither of which match the matrix provided by matrix_save (the first is right with the shift, but not the rotations, while the second is close with the rotations, but not the shifts).


Honestly, the best match (just playing with a few reasonable options) seems to be

S (ZXY)inv = S Yinv Xinv Zinv = {
{0.997224814347226, 0.03991994867019513, 0.06284160523339294, 2.0358},
{-0.03411788020026906,0.9952811250128277, -0.09083750571124193, 3.37123},
{-0.06617129211962466,0.08844139240971281, 0.9938810191405462, 24.20178},
{0.0, 0.0, 0.0, 1.0}
}


Thanks Again,
-Chad