A method, a system, and a computer-readable medium are provided which provide an efficient data layout for image data and fast access to samples of an image stored in hierarchical z-order format. An array of image data of a physical entity is ordered in a hierarchical z-order at a computing device. Data blocks are created from the array ordered based on the hierarchical z-order. Data files containing a predetermined number of successive data blocks are created from the created data blocks. A directory structure is created in a file system of a second computing device based on the hierarchical z-order. The created data files are stored in the created directory structure based on the hierarchical z-order.