Schnittlinie

Schnittlinie (literally “cutting line”) is a term used in geometry, technical drawing, and related disciplines to describe the line along which a cutting plane intersects a solid or surface, thereby defining the boundary of a cross-section.

In mathematics, a cutting plane intersecting a 3D object yields an intersection that is usually a curve. A Schnittlinie is that curve projected into a drawing or plane, and in the special case of two planes cutting each other, the intersection is a straight line—the Schnittlinie of the two planes.

In technical drawing and CAD, the Schnittlinie marks where the object is cut to expose interior features. The line is typically drawn on projection views to indicate the location of the cross-section; the exposed surfaces are often hatched to distinguish material. The precise appearance of the Schnittlinie depends on standards and conventions.

In architecture, mechanical engineering, and civil engineering, Schnittlinien enable engineers and builders to inspect internal configurations such as walls, ribs, joints, and voids, without altering external contours.

In geology and earth science, a cross-section line on a map or profile denotes the line along which a subsurface section is drawn, revealing strata, faults, and borehole data along that trajectory.

Etymology and usage: the term derives from German Schnitt (cut) and Linie (line). While its geometric meaning is the locus of points common to a cutting plane and a surface, in practice Schnittlinie most often refers to the visible cross-section line used in drawings and diagrams.