Natural, recognizable features on the site or a series of survey stakes used to establish distances and elevations during trail construction.

a system of points with established positions or elevations, or both, which are used as fixed references in positioning map features.

Points in the three dimensional space, where Spline curves travel through. The 3D positions of the control points of a spline together with the bias values of each point completely define the way of the spline.

Points whose location is considered accurate and which are used as a reference by other points in a data set.

A set of points on the ground whose horizontal and vertical location is known. Control points are used as the basis for detailed surveys.

A system of points with established horizontal and vertical positions which are used as fixed references in positioning and relating map features, aerial photographs or remotely sensed images.

Handles that you use to change the curvature of a curved segment. See: Anchor Points, Control Points, End Points, Segments, Tangent Lines.

Exact positions of often-surveyed geographic features used to register map sheets and transform coordinates.

(n) Points used in conjunction with spline curves. These points are not part of the curve proper, but the relationship between the control points and the points on the curve is used to define the shape of the curve.