2004

Table Of Contents
Create 3D Objects | 299
Use object snaps and grid snap carefully to ensure the precision of your
model.
Use coordinate filters to drop perpendiculars and easily locate points in
3D based on the location of points on other objects.
Methods for Creating Wireframe Models
With AutoCAD you can create wireframe models by positioning any 2D
planar object anywhere in 3D space, using several methods:
Entering 3D coordinates. You enter coordinates that define the X, Y, and
Z location of the object.
Setting the default construction plane (XY plane) on which you will draw
the object by defining a UCS.
Moving or copying the object to its proper 3D location after you create it.
Wireframe modeling is a skill that requires practice and experience. The best
approach to learning how to create wireframe models is to begin with simple
models before attempting models that are more complex.
To drop a perpendicular line from a 3D point down to the XY plane
1 From the Draw menu, choose Line.
2 Use an object snap to specify a point on an object that is not on the XY
plane of the UCS.
This defines the first point of the line.
3 Enter .xy and then enter @ at the Of prompt.
This operation extracts the X and Y coordinate values from the first point.
4 Enter 0 to specify the Z value.
Using coordinate filters, the X and Y values extracted from the first point
are combined with a new Z value (0) to finish the definition of the second
point.
5 Press
ENTER to end the command.
Create Surfaces
A mesh represents an object’s surface using planar facets. The mesh density,
or number of facets, is defined in terms of a matrix of M and N vertices,
similar to a grid consisting of columns and rows. M and N specify the column
and row position, respectively, of any given vertex. You can create meshes in
both 2D and 3D, but they are used primarily for 3D.