CODEWITHSUNDEEP
c++matrixeigenrotational-matriceseuler-angles
desmond13
desmond13

Reputation: 3149

Roll pitch and yaw from Rotation matrix with Eigen Library

I need to extract the roll pitch yaw angles from a rotation matrix and I want to be sure that what I do is correct. 

    Eigen::Matrix< simFloat, 3, 1> rpy = orientation.toRotationMatrix().eulerAngles(0,1,2);
    const double r = ((double)rpy(0));
    const double p = ((double)rpy(1));
    const double y = ((double)rpy(2));

Is that correct? Because I was reading here: http://eigen.tuxfamily.org/dox/group__Geometry__Module.html#gad118fececd448d7485ffea4858775e5a

And I was a bit confused when it says, at the end of the description, in which intervals are defined the angles.

Upvotes: 11

Views: 48025

Answers (2)

TSL_
TSL_

Reputation: 2079

I think this is what you are looking for. Depending on how we use m.eulerAngles(0, 1, 2); Here's the code which get rotx, roty, rotz that is reconstructed with rotx*roty*rotz

Matrix3f m;
    
m = AngleAxisf(0.25*M_PI, Vector3f::UnitX())
  * AngleAxisf(0.5*M_PI, Vector3f::UnitY())
  * AngleAxisf(0.33*M_PI, Vector3f::UnitZ());
    
cout << "original rotation:" << endl;
cout << m << endl << endl;
    
Vector3f ea = m.eulerAngles(0, 1, 2); 
cout << "to Euler angles:" << endl;
cout << ea << endl << endl;
    
Matrix3f n;
n = AngleAxisf(ea[0], Vector3f::UnitX())
  * AngleAxisf(ea[1], Vector3f::UnitY())
  * AngleAxisf(ea[2], Vector3f::UnitZ()); 

cout << "recalc original rotation:" << endl;
cout << n << endl;

I also firstly use Eigen. It simply saves a lot of work!

Upvotes: 19

Rachit Bhargava
Rachit Bhargava

Reputation: 183

The answer by Shawn Le is correct but I think the line should be 

Vector3f ea = m.eulerAngles(2, 1, 0);

Then ea will hold the yaw pitch and roll value in that order. ZYX euler angle rotation is equivalent to XYZ fixed axis rotation which is nothing but roll pitch and yaw.

Upvotes: 6

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