Creating 3D Geometry - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 847

Moving and Rotating in 3D
When you moved objects in the 2D portion of this topic, terms like “left” and
“right” or “up” and “down” were acceptable to use because all movements were
associated with the sides of the drawing area. Even when you rotated the views in
Chapter 10 it was so you could relate movements to the screen more easily. When
working in 3D, however, these terms are no longer easily translated from your
intent to proper movement on the screen. Let's take the back door block-out for
example. If I told you to move it “forward,” would that mean into the cabin, away
from the cabin, or toward the bottom of the screen? You see what the problem is.
When the viewpoint is significantly different than what you may expect, say, from
the bottom or the back, then front or back may be even more confusing.
the First Right-Hand Rule
To help you stay oriented in 3D space, the UCS becomes more important. Each
colored axis of the UCS icon points in the positive direction for that particular axis.
To understand whether a movement, particularly in the z-axis, is in the positive
direction, you should be familiar with the first of two “right-hand rules.” This rule
relates your hand to the UCS and helps clarify the axis directions. Start by extend-
ing the thumb and index finger on your right hand to form an “L” shape; then
project your middle finger perpendicular to your palm as shown in Figure 16.20.
The rule states: When your thumb is pointing in the positive X direction and your
index finger is pointing in the positive Y direction, your middle finger must be
pointing in the positive Z direction.
To apply this to the window block-outs in our cabin example, compare your
right hand to the UCS icon in the drawing area. With your thumb pointing
toward the cabin, and your index finger pointing away from the cabin and to the
left, your middle finger then points toward the top of the screen. This indicates
that the window block-outs, which are currently resting on the ground plane
with the door block-out, need to be moved in the positive Z direction.
1. Click the 3D Move tool in the Modify panel on the Home tab.
With the 3D Move tool you move objects using the Move grip tool,
which looks similar to the UCS icon.
2. At the Select objects: prompt, select the bathroom window block-
out and then press ↵ to end the selection process.