A 3D reconstruction system for performing a determination of a tissue field is disclosed. The system has a structured light arrangement with a projector device configured to project a structured light beam onto at least a section of the tissue field, an image acquisition device configured for acquiring frames comprising reflections of the structured light beam from the tissue field, each frame comprises a set of pixel data associated with a time attribute, and a computer system. The projected structured light beam is stored as reference structured light data set comprising data representing a set of light features. The computer is configured for • in real time receiving frames acquired by the image acquisition device, • recognizing a plurality of light features including primary light features of the set of light features from the received set of pixel data, • matching the recognized primary light features with corresponding light features of the projected structured light beam and based on the matches estimating the spatial position of the projector device relative to at least a part of the tissue field, and • performing at least one determination of the tissue field based on the spatial position of the projector device and the recognized light features.
