An apparatus for automated seam welding of a work piece comprising a base plate with a pattern of upstanding profiles, said work piece being arranged on a support base, said apparatus including: - an overhead support with at least one robotic device, characterised in - at least one overhead laser scanner, such as a LIDAR scanner, over said work piece, for establishing a global 3D topographical image of said work piece by relative overhead movement across said work piece of said at least one overhead scanner, - - said robotic device including an articulated arm and being configured for assuming active positions wherein a head of said articulated arm is closer to said support base in local areas of said work piece, - - - said head including a distance sensor, - - said robotic device further being configured for carrying a welding tool with a welding gun with a welding torch, - - - - said distance sensor being positionable in different positions within each of said local areas of said work piece in said active positions, - - - - - said distance sensor being configured for generating local information about the position of the ends of profiles being within or delimiting said local areas and/or of intersections between profiles being within or delimiting said local areas, and - a computer device for storing data representing said established global 3D topographical image of said work piece and data representing said generated local information about said work piece, - said computer device being configured for identifying each of said profiles by comparing said data representing said global 3D topographical image with information stored in a database and representing geometrical data for each of said profiles. - an overhead support with at least one robotic device, characterised in - at least one overhead laser scanner, such as a LIDAR scanner, over said work piece, for establishing a global 3D topographical image of said work piece by relative overhead movement across said work piece of said at least one overhead scanner, - - said robotic device including an articulated arm and being configured for assuming active positions wherein a head of said articulated arm is closer to said support base in local areas of said work piece, - - - said head including a distance sensor, - - said robotic device further being configured for carrying a welding tool with a welding gun with a welding torch, - - - - said distance sensor being positionable in different positions within each of said local areas of said work piece in said active positions, - - - - - said distance sensor being configured for generating local information about the position of the ends of profiles being within or delimiting said local areas and/or of intersections between profiles being within or delimiting said local areas, and - - said robotic device including an articulated arm and being configured for assuming active positions wherein a head of said articulated arm is closer to said support base in local areas of said work piece, - - - said head including a distance sensor, - - - said head including a distance sensor, - - said robotic device further being configured for carrying a welding tool with a welding gun with a welding torch, - - - - said distance sensor being positionable in different positions within each of said local areas of said work piece in said active positions, - - - - - said distance sensor being configured for generating local information about the position of the ends of profiles being within or delimiting said local areas and/or of intersections between profiles being within or delimiting said local areas, and - - - - said distance sensor being positionable in different positions within each of said local areas of said work piece in said active positions, - - - - - said distance sensor being configured for generating local information about the position of the ends of profiles being within or delimiting said local areas and/or of intersections between profiles being within or delimiting said local areas, and - - - - - said distance sensor being configured for generating local information about the position of the ends of profiles being within or delimiting said local areas and/or of intersections between profiles being within or delimiting said local areas, and - a computer device for storing data representing said established global 3D topographical image of said work piece and data representing said generated local information about said work piece, - said computer device being configured for identifying each of said profiles by comparing said data representing said global 3D topographical image with information stored in a database and representing geometrical data for each of said profiles.