Aerial photographs at the beginning of the film and others that you can see over it, were digitalized by Israel Millan from photographs of Hector Garrido. This photographer has published a book, "Armonía fractal de Doñana y las marismas" (Fractal Harmony of Doñana and marshes) which includes some of the images used in the film. The images correspond to various marshes of Andalucia, such as the ones of Coto Doñana and the Salinas de San Fernando in Cádiz.