US Patent 11238659 Caching and updating of dense 3D reconstruction data

A method to efficiently update and manage outputs of real time or offline 3D reconstruction and scanning in a mobile device having limited resource and connection to the Internet is provided. The method makes available to a wide variety of mobile XR applications fresh, accurate and comprehensive 3D reconstruction data, in either single user applications or multi-user applications sharing and updating the same 3D reconstruction data. The method includes a block-based 3D data representation that allows local update and maintains neighbor consistency at the same time, and a multi-layer caching mechanism that retrieves, prefetches, and stores 3D data efficiently for XR applications. Altitude information, which may be expressed as a building floor for indoor environments, may be associated with sparse and/or dense representations of the physical world, to increase the accuracy of localization results and/or in rendering virtual content more realistically.