Joint calibration of RGB and X-ray cameras

We detail our experiences with ad hoc designed phantoms and their role in joint camera calibration scenarios. In these setups, one of the cameras is a conventional X-ray imaging system and the other is a complementary and rigidly attached RGB camera. The applications of these dual imaging systems (i.e., radiograph stitching, 3D reconstruction, etc.) are becoming trendy and are already being explored by many research groups and healthcare institutions. These combined modalities must be first geometrically and optically calibrated in order to derive relevant parameters that will later interplay during each experiment or clinical trial.