Abstract: A golf ball 2 has, on a surface thereof, a rugged pattern composed of a land 10 and a large number of dimples 8. A process for designing the rugged pattern includes the steps of: (1) arranging a large number of generating points on a surface of a phantom sphere; (2) assuming a large number of Voronoi regions on the surface of the phantom sphere by a Voronoi tessellation based on the large number of generating points; (3) calculating centers of gravity of the Voronoi regions and setting the centers of gravity as new generating points; (4) assuming a large number of new Voronoi regions on the surface of the phantom sphere by a Voronoi tessellation based on a large number of the new generating points; and (5) assigning dimples and a land to the surface of the phantom sphere based on contours of the new Voronoi regions.

Abstract: A cross-sectional shape of each of dimples 8 of a golf ball is a wave-like curve. The wave-like curve has two first projections 16, two second projections 18, two first recesses 20, and two second recesses 22. A circular arc 14 passes through one edge Ed, a deepest point Pd, and another edge Ed. Each first projection 16 is located above the circular arc 14. Each second projection 18 is located above the circular arc 14. Each first recess 20 is located below the circular arc 14. Each second recess 22 is located below the circular arc 14. The ratio of the distance Lp from an edge Ed to a peak Pp to the radius (Di/2) of the dimple 8 is equal to or greater than 20% but equal to or less than 70%.

Abstract: A designing method according to the present invention includes the steps of: (1) dividing a surface of a phantom sphere of a golf ball 2 into a plurality of units U by division lines 14 obtained by projecting edge lines of a regular polyhedron inscribed in the phantom sphere, on the surface of the phantom sphere; (2) obtaining a base pattern by randomly arranging a plurality of dimples 8 in one unit U such that the dimples 8 do not overlap each other; and (3) developing the base pattern over other units U such that patterns of two adjacent units U are not mirror-symmetrical to each other. The regular polyhedron is preferably a regular dodecahedron or a regular icosahedrons.

Abstract: A golf ball 2 has a large number of dimples 8 on a surface thereof. A trajectory of the golf ball 2 is divided into first to fourth segments. An average CD1 of drag coefficients CD and an average CL1 of lift coefficients CL in the first segment are equal to or less than 0.225 and 0.180, respectively. An average CD2 of drag coefficients CD and an average CL2 of lift coefficients CL in the second segment are equal to or less than 0.250 and 0.220, respectively. An average CD3 of drag coefficients CD and an average CL3 of lift coefficients CL in the third segment are equal to or greater than 0.260 and 0.220, respectively. An average CD4 of drag coefficients CD and an average CL4 of lift coefficients CL in the fourth segment are equal to or greater than 0.250 and 0.200, respectively.

Abstract: A golf ball has, on a surface thereof, a rugged pattern composed of a land and a large number of dimples. A method for designing the rugged pattern includes the steps of: (1) assuming a large number of circles on a surface of a phantom sphere; (2) assuming a large number of generating points 16 based on positions of the large number of circles; (3) assuming a large number of Voronoi regions 18 on the surface of the phantom sphere by a Voronoi tessellation based on the large number of generating points 16; and (4) assigning a dimple and a land to the surface of the phantom sphere based on contours of the large number of Voronoi regions 18.

Abstract: A golf ball 2 has a large number of dimples 8 and a land 10. A rugged pattern is formed on the surface of the golf ball 2 by these dimples 8 and the land 10. These dimples 8 are arranged in a random manner. Each dimple 8 has a crater shape. For designing the rugged pattern, a Cellular Automaton method is used. A fluctuation range Rh of the golf ball 2 that is an index indicating the aerodynamic characteristic during PH rotation is 1.9 mm or less. A fluctuation range Ro of the golf ball 2 that is an index indicating the aerodynamic characteristic during POP rotation is 1.9 mm or less. The absolute value of the difference dR between the fluctuation range Ro and the fluctuation range Rh is 0.4 mm or less.

Abstract: The golf ball 2 has a northern hemisphere N and a southern hemisphere S. The northern hemisphere N is adjacent to the southern hemisphere S across an equatorial line Eq. Each of the northern hemisphere N and the southern hemisphere S has a pole vicinity region 14 and an equator vicinity region 16. Each of the pole vicinity region 14 and the equator vicinity region 16 has a large number of dimples. The dimple pattern of the pole vicinity region 14 includes three units that are rotationally symmetrical to each other about a pole Po. The dimple pattern of the equator vicinity region 16 includes six units that are rotationally symmetrical to each other about the pole Po. The sum (Ps+Pp) of a peak value Ps and a peak value Pp of the golf ball 2 is equal to or greater than 600 mm.

Abstract: Based on a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. Preferably, the parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Based on a maximum value and a minimum value of the data constellation, a fluctuation range is calculated. By dividing the fluctuation range by a total volume of the dimples, an evaluation value is calculated. This value is calculated for each of PH rotation and POP rotation.

Abstract: A process for designing the rugged pattern includes the steps of: assuming a plurality of states; assuming a large number of cells on a spherical surface; assigning any one of the plurality of states to each cell; assigning, as an attribute, any one of INSIDE, OUTSIDE and BOUNDARY to the each cell based on the state of the each cell and states of a plurality of cells located adjacent to the each cell; assuming craters based on the attributes of the large number of cells; and updating the attribute of the 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 the each cell.

Abstract: A golf ball 2 has, on a surface thereof, a dimple pattern consisting of a land 10 and a large number of dimples 8. A process for designing the dimple pattern includes the steps of: (1) randomly arranging a large number of points on the surface of a phantom sphere; (2) calculating a distance between a first point and a second point which is a point closest to the first point; (3) deciding a radius on the basis of the distance; (4) assuming a circle which has a center at the first point and has the radius; and (5) assuming a dimple whose contour coincides with the circle. The dimples 8 are randomly arranged.

Abstract: A golf ball 2 has, on a surface thereof, a rugged pattern consisting of a land 10 and a large number of dimples 8. A method for designing the rugged pattern includes the steps of: (1) randomly arranging a large number of generating points on the surface of a phantom sphere; (2) assuming a large number of Voronoi regions on the surface of the phantom sphere based on the generating points; and (3) assigning a land to the vicinity of the contour of each Voronoi region and assigning a dimple to a portion of the surface of the phantom sphere other than the land.

Abstract: A golf ball 2 has a large number of craters 8. A rugged pattern is formed on the golf ball 2 by the craters 8. A process for designing the rugged pattern includes the steps of: assuming a plurality of states; assuming a large number of cells on a spherical surface; assigning any one of the plurality of states to each cell; assigning, as an attribute, any one of INSIDE, OUTSIDE and BOUNDARY to the each cell based on the state of the each cell and states of a plurality of cells located adjacent to the each cell; assuming craters based on the attributes of the large number of cells; and updating the attribute of the 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 the each cell.

Abstract: A golf ball 2 has a large number of craters 8. A rugged pattern is formed on the golf ball 2 by the craters 8. A process for designing the rugged pattern includes the steps of: assuming a plurality of states; assuming a large number of cells on a spherical surface; assigning any one of the plurality of states to each cell; assigning, as an attribute, any one of INSIDE, OUTSIDE and BOUNDARY to the each cell based on the state of the each cell and states of a plurality of cells located adjacent to the each cell; assuming craters based on the attributes of the large number of cells; and updating the attribute of the 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 the each cell.

Abstract: On the basis of a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. A preferable parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Fourier transformation is performed on the data constellation to obtain a transformed data constellation. On the basis of a peak value and an order of a maximum peak of the transformed data constellation, an aerodynamic characteristic of the golf ball is determined. The peak value and the order of the maximum peak are calculated for each of PH rotation and POP rotation.

Abstract: On the basis of a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. A preferable parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Fourier transformation is performed on the data constellation to obtain a transformed data constellation. On the basis of a peak value and an order of a maximum peak of the transformed data constellation, an aerodynamic characteristic of the golf ball is determined. The peak value and the order of the maximum peak are calculated for each of PH rotation and POP rotation.

Abstract: Based on a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. Preferably, the parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Based on a maximum value and a minimum value of the data constellation, a fluctuation range is calculated. By dividing the fluctuation range by a total volume of the dimples, an evaluation value is calculated. This value is calculated for each of PH rotation and POP rotation.

Abstract: Based on a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. Preferably, the parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Based on a maximum value and a minimum value of the data constellation, a fluctuation range is calculated. By dividing the fluctuation range by a total volume of the dimples, an evaluation value is calculated. This value is calculated for each of PH rotation and POP rotation.

Abstract: A golf ball 2 includes a spherical core 4 and a cover 6 positioned outside the core 4. The golf ball 2 further has dimples 8 on a surface thereof. The core 4 is obtained by crosslinking a rubber composition. The difference between a hardness H(5.0) at a point that is located at a distance of 5 mm from the central point of the core 4, and a hardness Ho at the central point is equal to or greater than 6.0. The difference between a hardness H (12.5) at a point that is located at a distance of 12.5 mm from the central point, and the hardness H(5.0) is equal to or less than 4.0. The difference between a hardness Hs at the surface of the core 4 and the hardness H(12.5) is equal to or greater than 10.0. The difference between the hardness Hs and the hardness Ho is equal to or greater than 22.0. There is no zone in which a hardness decreases from the central point to the surface. The rubber composition of the core 4 includes 2-naphthalenethiol. A cross-sectional shape of each dimple 8 is a wave-like curve.