The derivative measures the sensitivity to change of the output with respect to a change in the input. I photographed Moscow in 2015 and 3 years later, as I was looking the photos on my screen, I re-shot them. This change of view offered me the distance in space and time needed to distance myself from the theme and at the same time returning back to its space. (A derivative work is an expressive creation that includes major copyrightable elements of an original, previously created first work (the underlying work). The derivative work becomes a second, separate work independent in form from the first. The transformation, modification or adaptation of the work must be substantial and bear its author’s personality sufficiently to be original and thus protected by copyright.)