Process for designing rugged pattern on golf ball surface

A process for making a rugged pattern on a surface of a golf ball, the process comprising the steps of:

• providing a phantom sphere corresponding to the golf ball, a diameter of the phantom sphere being the same as that of the golf ball;
• dividing a surface of the phantom sphere into a large number of cells;
• determining a plurality of states;
• assigning any one of the plurality of states to each cell, wherein assigning the plurality of states includes determining, using a computer processor, whether or not to change a state of each cell based on a value E calculated by the following mathematical formula:
• E=W1*NR1+W2*NR1-R2, wherein in the mathematical formula, W1 denotes a first concentration, Nm denotes the number of cells that are included in a first circle, not located at the center of the first circle and in a specific state, W2 denotes a second concentration, NR1-R2 denotes the number of cells that are included in a second circle, not included in the first circle and in a specific state, the first concentration is positive, the second concentration is negative, the first circle has the center at said each cell and an index radius of R1, the second circle has a center at said each cell and an index radius of R2, and the radius R2 is greater than the radius R1;
• assigning, as an attribute, any one of INSIDE, OUTSIDE and BOUNDARY to said each cell based on the state of said each cell and states of a plurality of cells located adjacent to said each cell;
• determining craters based on the attributes of the large number of cells;
• updating the attribute of said each cell so as to enlarge the areas of the craters, based on the attribute of said each cell and the attributes of the plurality of cells located adjacent to said each cell;
• and
• forming craters on the surface of the golf ball conforming to the enlarged craters on the surface of the phantom sphere to form the rugged pattern.