Hello all,

Using Eigen::AngleAxisf to generate rotation matrices, I have found that the results are dependent on the magnitude of the input axis. That is to say, if I normalize the input axis to affine3f the results are different (and correct) compared to the results without normalization. This was, for me at least, rather non-intuitive. See this snippet of code:

Code: Select all

    Eigen::Vector3f one;
    Eigen::Vector3f two;
    one<<.056,1.3,19;
    one.normalize();
    two<<.032,.001,10;
    two.normalize();
   
    Eigen::Vector3f cross  = one.cross(two);
    Eigen::Affine3f without_normalization;
    without_normalization = Eigen::AngleAxisf(.05, cross);
    Eigen::Affine3f with_normalization;
    with_normalization = Eigen::AngleAxisf(.05, cross.normalized());
   
    std::cout<<"without normalization of axis in angleaxisf:\n"<<without_normalization.linear()<<std::endl;
   
    std::cout<<"with normalization of axis in angleaxisf:\n"<<with_normalization.linear()<<std::endl;

which results in this output

without normalization of axis in angleaxisf:
0.998756 1.0924e-05 1.25782e-05
-1.0881e-05 0.99875 -0.00340663
-1.26153e-05 0.00340663 0.99875
with normalization of axis in angleaxisf:
1 0.000164571 0.000180807
-0.000155329 0.99875 -0.0499786
-0.000188806 0.0499786 0.99875

Is this known behavior?

best,

Andrew

Whoops, so I'm a dufus -- the docs mention this, although the tutorial page on geometry does not.

This has been clarified in the manual.