Local feature size refers to several related concepts in computer graphics and computational geometry for measuring the size of a geometric object near a particular point.

• Given a smooth manifold${\displaystyle M}$, the local feature size at any point ${\displaystyle x\in M}$ is the distance between ${\displaystyle x}$ and the medial axis of ${\displaystyle M}$.^[1]
• Given a planar straight-line graph, the local feature size at any point ${\displaystyle x}$ is the radius of the smallest closed ball centered at ${\displaystyle x}$ which intersects any two disjoint features (vertices or edges) of the graph.^[2]

Definitions of local feature size. In each case, the local feature size at the blue points is the radius of the associated blue circle.

Local feature size for a smooth manifold (black) with medial axis (red).

Local feature size for a planar straight-line graph.

• Nearest neighbour function