A method of performing and monitoring a processing step on a workpiece using a system having a projector, a photogrammetric device and a control unit knowing the relative position of the projector and the photogrammetric device, comprises the following steps: referencing to determine a pose of the workpiece with respect to the projector and the photogrammetric device in a predetermined coordinate system; projection of a work instruction onto the workpiece; processing of the workpiece by a worker; and monitoring of the processing by scanning at least a portion of a surface of the workpiece, wherein all steps, with the exception of the processing by the worker, are performed by the device and wherein all steps are performed at the same workstation within a framework of an integrated process.