Beluga named requirements: PointCloud

A type P satisfies PointCloud requirements if given p a possibly const instance of P:

• P::Scalar is defined and is a scalar type to be used for x, y and z coordinates values,

• p.points()returns a view to the unorganized 3D point collection ofEigen::Map<Eigen::Matrix3X>type, -p.origin()returns the transform, ofSophus::SE3d` type, from the global to local frame in the sensor space;