Extrusion

Extrusion is three-dimensional extension for features. An extruded point becomes a line; an extruded line becomes a wall; an extruded polygon becomes a block.

Examples of extruded features.

Features can be extruded by various methods, as shown below.

No extrusion

An unextruded line feature. The line vertices are marked by dark and light blue points.

Adding to a feature's base heights

Each feature vertex is extruded upward by the same specified value (50 units, in this example). This method can be applied to points and lines.

Adding to a feature's minimum height

The lowest vertex in the feature is extruded by the specified value (50). The lowest vertex has a base height of 50, so it is extruded upward to 100. All other vertices are extruded to the same absolute value of 100; therefore, the vertices with base heights of 150 are extruded downward. This extrusion method can be applied to lines and polygons.

Adding to a feature's maximum height

The highest vertex in the feature is extruded upward by the specified value (50). The highest vertex has a base height of 150, so it is extruded to 200. All other vertices are extruded to the same absolute value of 200. This extrusion method can be applied to lines and polygons.

Extruding to a value

All vertices are extruded to the specified value (50). The highest vertices have base heights of 150, so they are extruded downward 100 units. The lowest vertices already have base heights of 50, so they are not extruded. This extrusion method can be applied to points, lines, and polygons.