nearround

Nearround is a descriptive term used across disciplines to refer to shapes, objects, or concepts that are almost circular but not perfectly round. In geometry and metrology, a shape is described as nearround when its boundary lies within a specified tolerance of a circle of comparable size. The exact definition of tolerance can vary by field, with common approaches including the Hausdorff distance to a best-fit circle, comparisons of area or perimeter differences to that of a circle with the same radius, or other metrics that bound deviation from circularity.

Applications of the concept occur in several domains. In industrial metrology, parts are often specified as nearround to indicate that their roundness meets a required tolerance without requiring a mathematically perfect circle. In computer graphics and computer vision, nearround shapes can arise due to rendering limits, noise, or image resolution; algorithms may classify a shape as nearround if its deviation from a circle falls below a chosen threshold. In mathematics and applied analysis, nearroundness can describe curves or regions that are perturbations of a circle, useful for perturbation theory, stability studies, and shape optimization.

Origin and usage of the term vary. Nearround is not a fixed technical term in standard glossaries; it is typically used descriptively or as a coined term in specific research papers or industry contexts. It is related to, but distinct from, formal notions such as circle, roundness, and circularity, which have precise, established definitions.