Non-square grids: A new trend in imaging and modeling?

The raster format of images and data is commonly intended as a synonymous of a square grid. Indeed, the square is not the only shape that can tessellate the plane. Other grids are well-known, and recently they have moved out of the fields of art and mathematics, and have started being of interest for technological applications. After introducing the main types of non-square grids, this paper presents experiences of practical uses of non-square grids, especially the hexagonal one, in various fields, including digital imaging, geographic systems, and their applications in sciences like medicine, environmental monitoring, etc. We conclude with considerations on the state of the art and perspectives for the future. In our opinion, the research is mature enough to prefigure a broader diffusion of some non-square grids, especially the hexagonal one.