Hand tracking for interaction feedback

Apparatus is described which has a memory configured to receive captured sensor data depicting at least one hand of a user operating the control system. The apparatus has a tracker configured to compute, from the captured sensor data, values of pose parameters of a three dimensional (3D) model of the hand, the pose parameters comprising position and orientation of each of a plurality of joints of the hand. A physics engine stores data about at least one virtual entity. The physics engine is configured to compute an interaction between the virtual entity and the 3D model of the hand based at least on the values of the pose parameters and data about the 3D model of the hand. A feedback engine is configured to trigger feedback to the user about the computed interaction, the feedback being any one or more of visual feedback, auditory feedback, haptic feedback.