Extrusion is the process of stretching a flat, 2D shape vertically to create a 3D object in a scene. For example, you can extrude building polygons by a height value to create three-dimensional building shapes. Only points, lines, and polygons support extrusion. When you extrude a layer in the 2D Layers category in the Contents pane, it is move to the 3D Layers category.
Point and multipoint features become hollow vertical columns when extruded, regardless of the point symbol applied. Extrusion is a good way to highlight locations in 3D. You can extrude points based on an attribute to create columns of different lengths to visually represent variability in the data.
A comparison of point features on the ground and point features extruded to lines:
Extruded line features appear as walls. This can be an effective way to represent and highlight boundaries in 3D. You can extrude based on an attribute value to show walls of varying heights, which can be an effective way to represent the magnitude of flow or other movement.
A comparison of a line feature on the ground and a line feature extruded to a wall:
Polygon features are extruded vertically to create blocks. This is an easy way to represent building footprints as simple 3D buildings. You can also extrude polygons by an attribute to create 3D prism maps, such as property prices, county population, or census block income.
A comparison of building footprints on the ground and building footprints extruded to three-dimensional shapes:
Follow these steps to extrude features.
- Select the feature layer you want to extrude in the Contents pane.
- Under Feature Layer, on the Appearance tab, in the Extrusion group, click the Type drop-down arrow. Choose a feature extrusion type.
Features are not extruded. This is the default.
Add extrusion to each feature's minimum height. A z-value is calculated by adding the extrusion height to the minimum z-value of each feature. They are extruded to a flat top at that value. This option is not available for point features.
Add extrusion to each feature's maximum height. A z-value is calculated by adding the extrusion height to the maximum z-value of each feature. They are extruded to a flat top at that value. This option is not available for point features.
Add extrusion to each vertex of each feature's base height . A z-value is calculated for each vertex of the feature's base and each feature is extruded to those z-values. In the case pf polygon features, top and base faces are created to connect to the extruded walls to construct a closed shape.
Each feature is extruded to the specified z-value as a flat top, regardless of the z-values of each feature.
When you set extrusion on a layer, you can choose to specify the extrusion unit for extrusion values. Under Feature Layer, on the Appearance tab, in the Extrusion group, click the Unit drop-down arrow. If the layer has a vertical coordinate system defined, the default extrusion unit is the vertical unit of the data source. Otherwise, the default extrusion unit is meters.
Set attribute value to extrude features
The extrusion text box is available if you choose any extrusion method except None. You can type a constant value or use the drop-down menu to choose a field of the attribute table of the feature layer. To define an expression, click the button next to the Expression text box. Optionally, choose to apply any operators to the attribute value. For example, if you have the height of each building floor as your attribute field, and you know how many floors the building has, you can add a multiplier to calculate building height.