Embodiments of the invention provide methods and apparatus to determine a coordinate system to use when traversing rays through a portion of a spatial index corresponding to a dynamic object which has a unique object coordinate system. An image processing system may take into consideration a number of factors including, but not limited to, a distance form a viewpoint to the dynamic object, a distance from the origin of the world coordinate system to the object coordinate system, a rate of traversal of the dynamic object, and a number of primitives which make up the object. These factors alone or together may indicate whether it is more efficient to perform ray intersection tests in an object coordinate system or in a world coordinate system. Embodiments of the invention may update a spatial index according to the selected coordinate system.