Hi Vincent,
I've struggled with Euler angle problems before. I have a set of routines for
converting. Check the computeYPRRotationMatrix() function below. If it produces the
same rotation matrix as your sequence (which I think it will), then the other function
will produce your Euler angles from the matrix.
josh
// Code snippets assume class data: yaw, pitch, roll in degrees
/**
* Computes the YPR rotation matrix:
*
* [cos(y)*cos(p) cos(y)*sin(p)*sin(r)-sin(y)*cos(r)
cos(y)*sin(p)*cos(r)+sin(y)*sin(r)]
* [sin(y)*cos(p) sin(y)*sin(p)*sin(r)+cos(y)*cos(r)
sin(y)*sin(p)*cos(r)-cos(y)*sin(r)]
* [-sin(p) cos(p)*sin(r) cos(p)*cos(r)
]
*/
private void computeYPRRotationMatrix()
{
// precomputations
double sp = Math.sin(Math.toRadians(pitch));
double cp = Math.cos(Math.toRadians(pitch));
double sy = Math.sin(Math.toRadians(yaw));
double cy = Math.cos(Math.toRadians(yaw));
double sr = Math.sin(Math.toRadians(roll));
double cr = Math.cos(Math.toRadians(roll));
// Create the matrix
matrix =
new Matrix3d(cy * cp, cy * sp * sr - sy * cr, cy * sp * cr + sy * sr,
sy * cp, sy * sp * sr + cy * cr, sy * sp * cr - cy * sr,
-sp, cp * sr, cp * cr);
}
/**
* Computes the Euler (YPR order) angles from the <code>matrix</code>.
*
* Check element [2][0] of <code>matrix</code> for <code>rowFlag</code>.
* Depending on the value of <code>rowFlag</code> the values of pitch, yaw
* and roll are computed as follows:<BR>
*
* <code>rowFlag</code> = 1.0:<BR>
* Y = atan2(-matrix[0][1], matrix[1][1]), P = -90.0, R = 0.0 <BR>
* <BR>
* <code>rowFlag</code> = -1.0:<BR>
* Y = atan2(matrix[0][1], matrix[1][1]), P = 90.0, R = 0.0 <BR>
* <BR>
* otherwise:<BR>
* Y = atan2(matrix[1][0], matrix[0][0]), P = asin(-matrix[2][0]),
* R = atan2(matrix[2][1], matrix[2][2]) <BR>
*/
private void computeEulerYPRAngles()
{
int rowFlag = (int) matrix.m20;
switch (rowFlag) {
case 1:
yaw = Math.toDegrees(Math.atan2(-matrix.m01, matrix.m11));
pitch = -90.0;
roll = 0.0;
break;
case -1:
yaw = Math.toDegrees(Math.atan2(-matrix.m01, matrix.m11));
pitch = 90.0;
roll = 0.0;
break;
default:
yaw = Math.toDegrees(Math.atan2(matrix.m10, matrix.m00));
pitch = Math.toDegrees(Math.asin(-matrix.m20));
roll = Math.toDegrees(Math.atan2(matrix.m21, matrix.m22));
break;
}
}
>>> Vincent St-Amour <[EMAIL PROTECTED]> 07/11/02 09:51AM >>>
Hello,
I build a rotation matrix from the 3 rotation angles ( Rotation
around X axis, rotation around Y axis and rotation around Z axis).
I want to know if it is possible to retreive those angle from a
rotation matrix ( the other way arround ) ?
Thank you all,
Vincent St-Amour
Montreal.
Here is how I build my matrix from the 3 rotation angles :
//-
-------
Matrix4d
lRotX = new
Matrix4d();
lRotX.setIdentity();
lRotX.rotX(
(float)
Math.toRadians(
X_Angle_Value
) );
//-
-------
Matrix4d
lRotY = new
Matrix4d();
lRotY.setIdentity();
lRotY.rotY(
(float)
Math.toRadians(
Y_Angle_Value
) );
//-
-------
Matrix4d
lRotZ = new
Matrix4d();
lRotZ.setIdentity();
lRotZ.rotZ(
(float)
Math.toRadians(
Z_Angle_Value
) );
//-
-------
Matrix4d
lResult =
new
Matrix4d();
lResult.setIdentity();
lResult.mul(
lRotX );
lResult.mul(
lRotY );
lResult.mul(
lRotZ );
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