1. An imaging apparatus for imaging an object, the imaging apparatus ( 1 ) comprising: a model providing unit ( 4 ) for providing a kinematics model ( 12 ) of a robot representing the object ( 3 ), wherein the kinematics model ( 12 ) is defined by kinematics parameters, a projection data providing unit ( 2 ) for providing projection data of the object ( 3 ), which correspond to different projection directions, a model modification unit ( 13 ) for modifying the kinematics model ( 12 ) by modifying the kinematics parameters such that a difference between simulated projection data, which are determined by simulating a forward projection of the kinematics model, and the provided projection data is minimized.