System for interaction between a computer implemented interactive application and a user located in an interactive zone of said system, said system comprising: - a passive object comprising a grasping portion for receiving a hand of said user and a marked portion comprising a distinctive spot having distinct visual property; - a depth-aware camera, said depth-aware camera being able to produce a depth-image of said interactive zone, said depth-aware camera being also able to produce a contrast image representing an intensity measure of at least a portion of an electromagnetic spectrum coming from a field of view of the depth-aware camera overlapping at least partially said interactive zone; - a controller for receiving the depth-image and the contrast image produced by said depth-aware camera, characterized in said controller being able to compute from said depth-image the 3D coordinates in said interactive zone of a set of skeleton joints belonging to said user, said set of skeleton joints comprising the wrist joints of said user, said controller being also able to extract the 2D coordinates (M,N) of said distinctive spot in said contrast image when said passive object is held by a user in said field of view, said controller being able to identify in which hand said user holds said passive object, said controller being configured to compute two possibilities for the 3D coordinates of said distinctive spot from the knowledge of i) the 3D coordinates of the wrist joint of said user, ii) the 2D coordinates (M,N) of said distinctive spot in said contrast image and of iii) a distance R between the wrist of the user's hand holding the passive object and the distinctive spot of said passive object, said controller being configured to select one of said two possibilities based on information received from said computer implemented interactive application, said controller being configured to provide to said computer implemented interactive application the selected possibility for the 3D coordinates of said distinctive spot. - a passive object comprising a grasping portion for receiving a hand of said user and a marked portion comprising a distinctive spot having distinct visual property; - a depth-aware camera, said depth-aware camera being able to produce a depth-image of said interactive zone, said depth-aware camera being also able to produce a contrast image representing an intensity measure of at least a portion of an electromagnetic spectrum coming from a field of view of the depth-aware camera overlapping at least partially said interactive zone; - a controller for receiving the depth-image and the contrast image produced by said depth-aware camera, characterized in said controller being able to compute from said depth-image the 3D coordinates in said interactive zone of a set of skeleton joints belonging to said user, said set of skeleton joints comprising the wrist joints of said user, said controller being also able to extract the 2D coordinates (M,N) of said distinctive spot in said contrast image when said passive object is held by a user in said field of view, said controller being able to identify in which hand said user holds said passive object, said controller being configured to compute two possibilities for the 3D coordinates of said distinctive spot from the knowledge of i) the 3D coordinates of the wrist joint of said user, ii) the 2D coordinates (M,N) of said distinctive spot in said contrast image and of iii) a distance R between the wrist of the user's hand holding the passive object and the distinctive spot of said passive object, said controller being configured to select one of said two possibilities based on information received from said computer implemented interactive application, said controller being configured to provide to said computer implemented interactive application the selected possibility for the 3D coordinates of said distinctive spot.