Upgrading your code from Eigen2 to Eigen3

To prevent conflicts with Eigen2 in packages that depend on both Eigen2 and Eigen3, the ROS version of Eigen3 uses a different namespace, Eigen3. In addition, all header files are in the subdirectory Eigen3 instead of Eigen now. eigen3 contains a script that performs the necessary renaming automatically. You can run it like this:

rosrun eigen3 rename_eigen_namespace `rospack find your_awesome_package`

If you still have problems, read this page to understand what changed. If that doesn't help, continue reading.

While upgrading PCL 0.2.9 to Eigen3, we found the following issues:

EIGEN_ALIGN_128

EIGEN_ALIGN_128 doesn't seem to exist anymore in Eigen3. Use EIGEN_ALIGN16 instead, which is defined as:

#define EIGEN_ALIGN16 EIGEN_ALIGN_TO_BOUNDARY(16)

in Macros.h

Eigen::ForceAligned

Eigen2 had Eigen::ForceAligned defined in Core/util/Constants.h, and its behavior seemed to be confusing. In Eigen3, ForceAligned was dropped, and we should use Eigen::Aligned instead. Check this thread for more information. So your our expressions will change from:

typedef Eigen::Map<Eigen::Vector4f, Eigen::ForceAligned> Vector4fMap;

to

typedef Eigen3::Map<Eigen3::Vector4f, Eigen3::Aligned> Vector4fMap;

VectorXx ().cwise ()

Eigen3 introduces a new storage concept called Array. All the cwise () operations that were previously defined on VectorXx (MatrixBase), are no longer valid. Here's an example:

Eigen::Vector4i xyz_offset (fields[x_idx].offset, fields[y_idx].offset, fields[z_idx].offset, 0);

xyz_offset.cwise () += input_->point_step;

needs to change to:

Eigen::Array4i xyz_offset (fields[x_idx].offset, fields[y_idx].offset, fields[z_idx].offset, 0);

xyz_offset += input_->point_step;

VectorXx ().start () / .end ()

VectorXx ().start () changed to VectorXx ().head (), and VectorXx.end () changed to VectorXx ().tail (). See http://eigen.tuxfamily.org/dox-devel/Eigen2ToEigen3.html for more information.

MatriXx ().corner ()

Check this.

Transfom3f

The Transform3f typedef is deprecated starting with eigen3.0-beta2. To make your old code work, change all instances of

Eigen3::Transfom3f

to

Eigen3::Affine3f

PCL (Point Cloud Library) specific changes

To make sure that our Point Cloud data is always aligned, both on 32bit architectures as well as on 64bit, we have changed the pcl::PointCloud<T> data type internally as follows. Instead of providing a:

std::vector <T> points;

we now use:

std::vector<T, Eigen3::aligned_allocator<T> > points;

This requires changes in your code wherever you use vectors of points manually. Example:

std::vector<pcl::PointXYZINormal>::iterator it;
it = std::unique(overlap_model.points.begin(), overlap_model.points.end(), pclUnique);

should now be

std::vector<pcl::PointXYZINormal, Eigen3::aligned_allocator<pcl::PointXYZINormal> >::iterator it;
it = std::unique(overlap_model.points.begin(), overlap_model.points.end(), pclUnique);