During the vertical extrusion the 2D model object – a block, edge or vertex – converts to one or several objects of the 3D model. Blocks transform into bodies, edges become vertical faces, vertices create vertical edges.
The 2D object which is subjected to extrusion we will call the source. All horizontal sections
of the 3D objects, extruded from the same 2D source are the same, and their projections to the
2D source plane coincide with this source. There are no intervals between the adjacent objects
extruded from the same source. In other words, 3D objects extruded from the same 2D source are
stacked on each other, and the boundary between these objects is the same source shifted vertically.
It is clear that only parameters of this extrusion are the heights of levels, where the horizontal
boundaries between the 3D extruded objects are located. When this height is defined we will say that
the corresponding height level is assigned to the extrusion source.
Number of the 3D objects, extruded from the source, is always less by 1 than number of levels assigned to this source, because there is no empty vertical space between neighboring 3D objects. Therefore at least 2 height levels should be assigned to 2D objects to perform its 3D extrusion.
Note: If some height level is assigned to 2D object of positive dimension (block or edge) it is automatically assigned to all 2D objects at its boundary. Dimension of these boundary objects is always less than the dimension of the original object. For example, if the height level 10 is assigned to the edge, then both vertices at its ends are also assigned the same height level 10. If the block has the height level 0, then all the boundary edges and nodes automatically have the height level 0 assigned.
Related Topic:
Model 3d Creating
Model Assign Heights
Model View 3D
Model Assign Labels