convert Matrix4f to Affine transformation in Eigen

source http://answers.ros.org/question/37609/counterpart-to-pcl_rostransformasmatrix/

Counterpart to pcl_ros::transformAsMatrix ?

• pcl_ros
• tf
• conversion
• tf_conversions

asked Jul 2 '12

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updated Jul 2 '12

jodafo 
190 ●1 ●5 ●11

Hi,

I understand pcl_ros::transformAsMatrix(const tf::Transform& bt, Eigen::Matrix4f &out_mat) can be used to convert a tf::transform to a 4x4 matrix describing the same transformation.

I am now looking for a method that does the same thing backwards, converting a 4x4 matrix to a tf::transform.

Is such a method already implemented somewhere?

Thanks

EDIT: Solution that works for me, thanks to Eric:

  Eigen::Matrix4f mf; //The matrix I want to convert
  Eigen::Matrix4d md(mf.cast());
  Eigen::Affine3d affine(md);
  tf::Transform transform;
  tf::TransformEigenToTF(affine, transform);

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A small info which might be helpful for others. For ROS hydro, tf::transformEigenToTF must be used.

balakumar-s (Dec 1 '13)

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answered Jul 2 '12

Eric Perko 
7050 ●43 ●80 ●135http://ericperko.com/

You should look at the tf_conversions package, specifically thetf::TransformEigenToTF function.

You would have to make an Eigen::Affine3d from your Eigen::Matrix4f. See the Eigen Geometry Module Tutorial (and linked docs for each class) for information on how to go about that. I expect it involves a conversion from Matrix4f to Matrix4d and then passing that to the Affine3d constructor, but I don't know the exact function calls and syntax required off the top of my head.

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Works, thank you.

jodafo (Jul 2 '12)

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