A camera objective for a camera includes a mask having a plurality of masking sections which are permeable for radiation of a first spectral range and are impermeable for radiation of a second spectral range different from the first spectral range. A request is received to perform a query of a multi-dimensional database, such as a cube, stored at a server computer. The 3-dimensional structure can be flexibly collapsible into 2-dimensional flat surfaces, with at least two of the surfaces not required to have any space between them when the structure is collapsed.