A method for compressing video data comprising: generating, from video graphics data which have not been rendered and for providing modeling objects to be rendered, vertex data corresponding to said objects; said objects comprising movable objects; rendering said video graphics data to produce a current frame of pixel data and a reference frame of pixel data; identifying the position of each of said movable objects within said reference frame; based upon said vertex data, defining a search area within said reference frame for calculating a motion vector for a block of pixel data within said current frame, said block containing at least a portion of a respective identified movable object, wherein the vertex data is used for the primitives for a respective identified movable object within said reference frame, and the search area for said blocks (405 - 411) is restricted to, with using the identified position of a respective identified movable object as a reference, a region surrounding the position of a respective identified movable object; and compressing said current frame based upon said motion vector; characterized in that said search area is defined based upon the viewport coordinates of vertexes corresponding to a respective identified movable object within said reference frame by defining the outer boundaries and vertexes of a rectangular region within the reference frame containing a respective identified movable object by the viewpoint coordinates of vertexes (417, 419, 421, 423) of the respective identified movable object; and uniformly expanding the boundaries of said rectangular region for defining said search area. generating, from video graphics data which have not been rendered and for providing modeling objects to be rendered, vertex data corresponding to said objects; said objects comprising movable objects; rendering said video graphics data to produce a current frame of pixel data and a reference frame of pixel data; identifying the position of each of said movable objects within said reference frame; based upon said vertex data, defining a search area within said reference frame for calculating a motion vector for a block of pixel data within said current frame, said block containing at least a portion of a respective identified movable object, wherein the vertex data is used for the primitives for a respective identified movable object within said reference frame, and the search area for said blocks (405 - 411) is restricted to, with using the identified position of a respective identified movable object as a reference, a region surrounding the position of a respective identified movable object; and compressing said current frame based upon said motion vector; characterized in that said search area is defined based upon the viewport coordinates of vertexes corresponding to a respective identified movable object within said reference frame by defining the outer boundaries and vertexes of a rectangular region within the reference frame containing a respective identified movable object by the viewpoint coordinates of vertexes (417, 419, 421, 423) of the respective identified movable object; and uniformly expanding the boundaries of said rectangular region for defining said search area.