In mathematics, self-affinity refers to a fractal whose pieces are scaled by different amounts in the x- and y-directions. We refer to these as being the 2-dimensional axes, like that of a grid. This means that in order to appreciate the self similarity of these fractal objects, they have to be rescaled using an anisotropic transformation. (From www.dictionary.com In physics and botany, the word 'anisotropy' means "of unequal physical properties along different axes".)