
3D drape
The method of superimposing thematic layers such as vegetation and roads on 3D perspective views.

Aspect
The directional measure of slope.

Base contour
The contour from which contouring starts.

Breaklines
Line features that represent changes of the land surface such as streams, shorelines, ridges, and roads.

Contour interval
The vertical distance between contour lines.

Contour lines
Lines connecting points of equal elevation.

Delaunay triangulation
An algorithm for connecting points to form triangles such that all points are connected to their nearest neighbors and triangles are as compact as possible.

Hill shading
A graphic method that simulates how the land surface looks with the interaction between sunlight and landform features. The method is also known as shaded relief.

Hypsometric tinting
A mapping method that applies color symbols to different elevation zones. The method is also known as layer tinting.

Maximun ztolerance
A TIN construction algorithm, which ensures that, for each elevation point selected, the difference between the original elevation and the estimated elevation from the TIN is within the specified tolerance.

Perspective view
A graphic method that produces 3D views of the land surfaces.

Slope
The rate of change of elevation at a surface location, measured as an angle in degrees or as a percentage.

Vertical profile
A chart showing changes in elevation along a line such as a hiking trail, a road, or a stream.

Viewing angle
A parameter for creating a perspective view, measured by the angle from the horizon to the altitude of the observer.

Viewing azimuth
A parameter for creating a perspective view, measured by the direction from the observer to the surface.

Viewing distance
A parameter for creating a perspective view, measured by the distance between the viewer and the surface.

VIP
An elevation point selection algorithm, which evaluates the importance of an elevation point by measuring how well its value can be estimated from the neighboring point values.

zscale
The ratio between the vertical scale and the horizontal scale in a perspective view. Also called the vertical exaggeration factor.

