Schematic overview of the SIMAGE model (A) and a few layers visualized (B and C). The blue-marked boxes (A) indicate layers that are further visualized (B and C). A simulation of the entire 'non-biological' signal is shown in B and C. Top row, sum of the gradient effects and density effects; second row, spot pin effects; third row: Gaussian noise. The bottom row shows the sum of all the effects pictured in the top three rows. The signals are plotted three-dimensionally (left side view) and two-dimensionally (right side view).