US Patent 7398178 Method of determining the irregularities of a hole

In a method of calculating irregularities of a hole, a center coordinate of an actual hole is set. Inner wall coordinates of the actual hole are obtained from the center coordinate of the actual hole. An area of the actual hole is determined based on the inner wall coordinates of the actual hole. A radius of a virtual hole is determined based on the area of the actual hole. A center coordinate of the virtual hole is determined based on the inner wall coordinates of the actual hole to obtain a circumference line of the virtual hole. A standard deviation of the inner wall coordinates of the actual hole relative to the circumference line of the virtual hole is calculated, thereby obtaining the irregularities of the actual hole.