A method of efficiently and accurately computing a pose of an image with respect to other image information. The image may be acquired with a camera on a portable device and the other information may be a map, such that the computation of pose localizes the device relative to the map. Such a technique may be applied in a cross reality system to enable devices to efficiently and accurately access previously persisted maps. Localizing with respect to a map may enable multiple cross reality devices to render virtual content at locations specified in relation to those maps, providing an enhanced experience for uses of the system. The method may be used in other devices and for other purposes, such as for navigation of autonomous vehicles.