Radu,
When I try to compile this:

int    
ROS_Link::samplePointsOnLine (pcl::PointXYZ p1, pcl::PointXYZ p2, double
 res, pcl::PointCloud<pcl::PointXYZ> &pts){
                    Eigen3::Vector4f dp = p2.getVector4fMap () - p1.getVector4fMap ();
                    // Compute the distance between the two points
                    double dist = dp.norm ();
                    dp.normalize ();
    
                    Eigen3::Vector4f axis_x (1.0, 0.0, 0.0), axis_y (0.0, 1.0, 0.0), axis_z (0.0, 0.0, 1.0);
                    // Compute the axis increments
                    double dx = res * dp.dot (axis_x);
                    double dy = res * dp.dot (axis_y);
                    double dz = res * dp.dot (axis_z);
 
                    int nr_pts = dist / res;
                    if (nr_pts < 1)
                    return (0);
 
                    pts.points.resize (nr_pts);
                    pts.width = nr_pts; pts.height = 1;
                    for (int m = 0; m < nr_pts; ++m)
                    {
                        pts.points[m].x = (m + 1) * dx + p1.x;
                        pts.points[m].y = (m + 1) * dy + p1.y;
                        pts.points[m].z = (m + 1) * dz + p1.z;
                    }
                    return (nr_pts);
    }

I have this error:
from /home/robot/src/autnavarc/ros-ana-pkg/han_Planner/src/ROS_Link.cpp:1:
/home/robot/src/ros/stacks/point_cloud_perception/eigen3/include/Eigen3/src/Core/Matrix.h:
 In constructor ‘Eigen3::Matrix<_Scalar, _Rows, _Cols, _Options, 
_MaxRows, _MaxCols>::Matrix(const typename 
Eigen3::ei_traits<Eigen3::Matrix<_Scalar, _Rows, _Cols, _Options, 
_MaxRows, _MaxCols> >::Scalar&, const typename 
Eigen3::ei_traits<Eigen3::Matrix<_Scalar, _Rows, _Cols, _Options, 
_MaxRows, _MaxCols> >::Scalar&, const typename 
Eigen3::ei_traits<Eigen3::Matrix<_Scalar, _Rows, _Cols, _Options, 
_MaxRows, _MaxCols> >::Scalar&) [with _Scalar = float, int 
_Rows = 4, int _Cols = 1, int _Options = 0, int _MaxRows = 4, int 
_MaxCols = 1]’:
/home/robot/src/autnavarc/ros-ana-pkg/han_Planner/src/ROS_Link.cpp:240:   instantiated from here
/home/robot/src/ros/stacks/point_cloud_perception/eigen3/include/Eigen3/src/Core/Matrix.h:261:
 error: ‘THIS_METHOD_IS_ONLY_FOR_VECTORS_OF_A_SPECIFIC_SIZE’ is not a 
member of ‘Eigen3::ei_static_assert<false>’
make[3]: *** [CMakeFiles/LaserScanToPointCloud.dir/src/ROS_Link.o] Error 1
make[3]: Leaving directory `/home/robot/src/autnavarc/ros-ana-pkg/han_Planner/build'
make[2]: *** [CMakeFiles/LaserScanToPointCloud.dir/all] Error 2
make[2]: Leaving directory `/home/robot/src/autnavarc/ros-ana-pkg/han_Planner/build'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/robot/src/autnavarc/ros-ana-pkg/han_Planner/build'

I don't know what is wrong with the size of the vector, any idea??

Thanks

Nicolas