Viewing, Hiding & Shading
You can view a drawing from any point in modelspace. Most 3D viewpoints display an axonometric view, some (e.g. DVIEW) can display perspective views.
You MUST create your models in MODEL VIEWS. i.e. The model must be created in MODELSPACE. AutoCAD does NOT supply a full set of 3D commands in the PAPERSPACE area.
The AutoCAD VPOINT command allows you to:
Enter the X,Y & Z co-ordinates of the desired viewpoint, e.g., 0,0,1 is a plan view.
Enter ROTATE to specify the angles from the X axis (in the XY plane) and `up' from the X,Y plane.
Press ENTER to enable the tripod and compass display. The compass, on the upper right, is a 2D representation of a globe, with the centre point being the North Pole, the inner ring being the equator and the entire outer ring is the South Pole. You can move the small crosshair until the axes are in the desired viewpoint.
AutoCAD has a more sophisticated 3D viewing command called DVIEW, which allows perspective, hidden and clipped views of selected entities. DVIEW uses a camera and target metaphor to help you position and control the view. Dview is well described in the AutoCAD on line reference manual, we will not attempt to describe the options and their use in this manual, however, you can enter DVIEW, select the objects, enter D for Distance, and then pick or type a large perspective vanishing point distance to create a perspective view.
You cannot do drawing construction or point in a perspective view: Its use is for Plotting, Shading, and Rendering.
The AutoCAD PLAN command views the drawing from either the current UCS (X,Y) plan or from the World Co-ordinate System X,Y plan. The plan command does not change the current UCS. Any co-ordinates entered after the PLAN command remain relative to the current UCS.
When viewing a drawing, from a 3D viewpoint, a wireframe display of all lines occurs. This includes lines that should be hidden by other objects. To eliminate the hidden lines before plotting, use the HIDE command. There are no options, the screen goes blank for a moment then the drawing is regenerated with the hidden lines suppressed.
The SHADE command will present a simple shaded representation of your model, with several different types of shade depending on the system variable SHADEDGE. SHADEDGE relates to the edges and colours used as follows:
DDVPOINT is a dialogue driven 3D viewpoint specification tool which is easier and quicker to use, you specify the angle from the X axis in the XY plane AND the angle up from the XY plane by pointing.
The UCSFOLLOW system variable can be used to force the current model view to a plan view whenever you change from one UCS to another.