Process for designing rugged pattern on golf ball surface

1. 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=W 1 *N R1 +W 2 *N R1-R2 , wherein in the mathematical formula, W 1 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, W 2 denotes a second concentration, N R1-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 R 1 , the second circle has a center at said each cell and an index radius of R 2 , and the radius R 2 is greater than the radius R 1 ;

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.

2. The process according to claim 1 , wherein:

the crater determining step includes the steps of:

assigning a recess to cells whose attributes are INSIDE or BOUNDARY; and

assigning a land to cells whose attributes are OUTSIDE,

wherein the crater is determined by a set of recesses.

3. The process according to claim 1 , wherein:

the crater determining step includes the steps of:

assigning a recess to cells whose attributes are INSIDE; and

assigning a land to cells whose attributes are OUTSIDE or BOUNDARY,

wherein the crater is determined by a set of recesses.

4. The process according to claim 1 , further comprising the step of calculating the areas of the craters and determining whether or not to perform the update of attribute.

5. The process according to claim 1 , wherein the update of attribute is repeated a plurality of times.

6. The process according to claim 1 , wherein the attributes of cells whose attributes are OUTSIDE and that are adjacent to cells whose attributes are BOUNDARY are changed to BOUNDARY at the step of updating the attribute of said each cell.

7. The process according to claim 1 , wherein:

the assignment of a state to said each cell is performed by the steps of:

deciding an initial state of said each cell;

determining whether or not to change the state of said each cell based on the states of the plurality of cells located adjacent to said each cell; and

updating the state of said each cell based on this determination.

8. The process according to claim 7 , wherein the initial state is decided in a random manner.

9. The process according to claim 7 , wherein the determination as to whether or not to change the state of said each cell and the update of the state of said each cell are repeated 3 times or more.

10. The process according to claim 7 , wherein the determination as to whether or not to change the state of said each cell and the update of the state of said each cell are performed by a Cellular Automaton method.

11. The process according to claim 10 , wherein the determination as to whether or not to change the state of said each cell and the update of the state of said each cell are performed by a reaction-diffusion model of the Cellular Automaton method.

12. The process according to claim 7 , wherein the number of the cells is 5000 or greater and 300000 or less.

13. The process according to claim 1 , wherein:

the initial state of said each cell is differentiated or undifferentiated;

when the value E calculated by the following mathematical formula (1) is positive, the state of said each cell is maintained if the state of said each cell is differentiated, and is changed to be differentiated if the state of said each cell is undifferentiated;

when the value E is zero, the state of said each cell is maintained; and

when the value E is negative, the state of said each cell is changed to be undifferentiated if the state of said each cell is differentiated, and is maintained if the state of said each cell is undifferentiated,

E=W 1 *N R1 +W 2 *N R1-R2   (1),

wherein in the mathematical formula (1), W 1 denotes a first concentration, N R1 denotes the number of differentiated cells that are included in a first circle and not located at the center of the first circle, W 2 denotes a second concentration, N R1-R2 denotes the number of differentiated cells that are included in a second circle and not included in the first circle, 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 R 1 , the second circle has a center at said each cell and an index radius of R 2 , and the radius R 2 is greater than the radius R 1 .

14. The process according to claim 1 , wherein the first concentration W 1 is 0.80 or greater and 1.20 or less.

15. The process according to claim 1 , wherein the second concentration W 2 is −0.70 or greater and −0.50 or less.

16. The process according to claim 1 , wherein the index radius R 1 is 2.20 or greater and 5.0 or less.

17. The process according to claim 1 , wherein the index radius R 2 is 3.0 or greater and 10.0 or less.