1. A control unit for an interactive multimedia video device processes data from an imaging device, and said imaging device is used to shoot a target image, the control unit including: a recognition device, which is used to recognize a target in the target image, wherein the target is a mark point group consisting of at least three mark points; a calculation device, which is used to calculate a position of the recognized target from the recognition device and make non-vector mathematic transformation for said position to obtain a position of an operation unit and output a position signal of the operation unit, wherein the non-vector mathematic transformation in said calculation device is a linear transformation, a quadratic transformation, or a projective matrix transformation, wherein the linear transformation uses the following transformation method: the position of the operation unit equals the value of the position of the target divided by a resolution of the imaging device and multiplied by a movable width of the operation unit, and wherein the recognition device further includes: a binarization device, employed to convert the target image to be binary; a searching device, which is used to connectively search said recognized binary image to obtain connected areas; a scoring device, which is used to calculate a sum of distances between fitting straight lines of said connected areas and a ratio of positions amongst the connected areas to obtain scores; and a determination device, which is used to determine the position of the target based on scores output from the scoring device.