Roundness error quick evaluation method based on regional search

A roundness error quick evaluation method based on a regional search comprises the steps of first measuring and obtaining coordinates of measuring points on the circumference of a cross section of a cylinder to be measured; and taking the center of a circle formed by three of the measuring points as an initial reference center of a circle, of which a initial search region is a square region which takes the center of the circle as the center and the maximum coordinate difference of the measuring points as the length of side, forming the region into matts, using a distance formula between two points for calculating the maximal value, minimal value and extreme value difference of the distance between the measuring points and the points on the matts, taking the points on the matt with the minimum extreme value different as the center, creating matts with half of the length of side to achieve the purpose of narrowing the searching region until the search termination condition is satisfied, stopping the search, and outputting the roundness error. The invention can be used for quickly and accurately calculating the roundness error.