An ordered object list is compared with an ordered ray list and if the coordinate value of an entry in the ray list is less than the coordinate value of an entry in the object list, then the ray is added to an active ray list, and a trace of that ray is made against all objects in an active object list. If the coordinate value of the entry in the ray list is greater than the coordinate value of the entry in the object list, then the coordinate value corresponding to the entry in the object list is added to an active object list, and a trace of all rays in the active ray list is made against that coordinate value. Rays and objects are removed from the active lists based on determinations as to whether a trace hit occurred and/or which object point is encountered.