The invention relates to an assembly (120) for determining an image of at least one region of a working face (122) of a rock mass (102), which working face is processed by a tunnel boring machine (180), wherein the assembly (120) comprises a rotatable drilling head (150) for the tunnel boring machine (180) for removing rock material of the working face (122), an image recording device (124), which is attached to the drilling head (150) in order to record image data of at least one section (600) of the working face (122), and an image processing device (126), which is designed to process image data of a plurality of sections (600) of the working face (122), which are recorded by means of the image recording device (124) in particular during the rotation of the drilling head (150), and for reconstructing the image of at least the region of the working face (122) from the image data of the plurality of sections (600) of the working face (122). In addition, a regular or continuous optical analysis of the working face can provide additional information that is useful for improving or optimizing the control of the tunnel boring machine.