The Radial and Axial Noise parameters on the Wood Parameters rollout determine the randomness or "irregularity" of the grain pattern in two directions.
Without any noise, rings and grain are uniform and look inorganic (upper-left cylinder). The defaults for both parameters produce moderate irregularities (upper-right cylinder).
Axial Noise: Controls the irregularity along the length of the grain (cylinder A). Default = 1.0.
Radial Noise: Controls the irregularity of the circular ring structure (cylinder B). Default = 1.0.
Cylinders A and B show each parameter acting alone. Cylinder C shows the combination of the same settings.
Radial, Axial Noise = 0,0 and 1,1
Angle Y = 90, Grain Thickness = 3
A: Radial, Axial Noise = 0,2
B: Radial, Axial Noise = 2,0
C: Radial, Axial Noise = 2,2
Angle Y = 90, Grain Thickness = 3