Superimposing the digital models and assigning each one a different color allows us to compare the real differences in depth and the changes from state to state. A composite overlay of Back (III), in orange, and Back (IV), in purple, confirms how the artist, starting with a plaster cast of the previous state, altered the form with massive additions of new material, leaving only portions of the head, columnar spine, and the ground of Back (III) visible in the final state.