The AutoCAD grid, a pattern of horizontal and vertical gridlines that mimic the
appearance of a sheet of graph paper, is used as an aid to drawing. You can set the grid to be visible or invisible. When set to visible, all but two of the horizontal and vertical gridlines display with a light gray color. One vertical gridline is colored green, whereas a single horizontal gridline is colored red. These colored gridlines reside at the 0 x-coordinate (red) and 0 y-coordinate (green),and they establish a boundary for Quadrant I of your drawing area, as shown in Figure 2.9 in Chapter 2.
Anything drawn above the red gridline and to the right of the green gridline
resides in Quadrant I, having positive x- and y-coordinate values. When working
in 3D, the green and red gridlines still represent the positive x- and y-coordinates
of your drawing area graphically; however, a third z-axis is also represented
in blue. Don’t worry too much about the z-axis quite yet, as it is discussed in
Chapter 16, “Creating 3D Geometry,” and Chapter 17, “Rendering and Materials.”
The area covered by the grid depends on a setting called Drawing Limits,
explained in the section “Setting Up Drawing Limits” later in this chapter. To
learn how to manipulate the grid size, you’ll make the grid visible, use the Zoom
In and Zoom Out commands to vary the view of the grid, and then change the
area over which the grid extends by resetting the drawing limits.
Before doing this, however, let’s take a look at the icon that sits in the lowerleft
corner of the drawing area. Known as the UCS, or User Coordinate System,
icon, it provides a visual cue to how we’re looking at the drawing, and it changes
when we’re looking from a 3D perspective. You’ll learn more about this in
Chapter 10, “Generating Elevations,” when we begin our discussion of 3D.
To become familiar with using and interacting with the grid in AutoCAD, follow
1. If the grid is not already displayed in the drawing area, move the
crosshair cursor to the status bar at the bottom of the screen, and
click the Grid Display button
The button changes from the Off to the On state (with a light blue
glow), and a series of horizontal and vertical lines appear in the
drawing area, representing a piece of graph paper.
These lines are the grid. Preset by default to be 1/2″ (10 mm) apart,
they extend across the entire drawing area. In the drawing area,
the gridlines may measure a greater distance apart, especially if
you zoom out in the drawing. This is because, in the relatively large
drawing area, lines spaced 1/2″ (10 mm) apart would be very dense,
and working with them would be difficult. AutoCAD automatically
reduces the density of the displayed gridlines to maintain a reasonable
appearance in the drawing area.
2. To open the Drafting Settings dialog box, right-click the Snap Mode
button and then choose Snap Settings from the context menu that
appears (see Figure 3.5).
F igu re 3 . 6 : The Snap And Grid tab of the Drafting Settings dialog box
4. In the Grid Behavior group, be sure Adaptive Grid is checked and
Display Grid Beyond Limits is unchecked. Then click OK.
The grid now covers only the area from the origin to 12″, 9″ (490
mm, 290 mm), the area defined by the limits of the drawing, but
extends to the extents of the drawing area. This will be evident after
Limits are discussed in the next section. The Adaptive Grid option
causes AutoCAD to reduce the number of the grid’s columns and
rows proportionately whenever the zoom factor would cause the grid
to become too dense to be effective.
5. To display a larger area within the drawing area, scroll the mouse wheel
by dragging it toward you or use the Zoom Out command by clicking the
drop-down arrow next to the Zoom tool from the View tab ➢ Navigate 2D
panel on the Ribbon.
The view changes, with more gridlines displaying in a denser configuration
(see Figure 3.7). You may need to zoom twice to see the
effect. Move the crosshair cursor to the lower-left corner of the grid,
and then move it to the upper-right corner. Notice that the coordinate
readout at the lower left of your screen shows a large negative
number for the lower-left corner and a larger positive number for the
upper-right corner. You’re displaying a greater amount of space in
the drawing area. A closer inspection of the grid will reveal one vertical
line colored green and a horizontal line colored red. The intersection
of these lines represents the origin, or 0,0 point, inside your
drawing. Any point above the red line and to the right of the green
line will have a positive coordinate value.
F igu re 3 . 7 : The grid after zooming out
6. To the right of the Grid Display button on the status bar, click the
Snap Mode button. Then move the cursor back onto the grid and look
at the coordinate readout again.
The cursor stops at each grid point intersection, even those that
are no longer displayed because of the zoom factor, and the readout
is to the nearest half inch. The Snap tool locks the cursor onto the
gridlines; even when the cursor isn’t on the visible grid but somewhere
outside it on the drawing area, the cursor maintains the grid
spacing and jumps from one location to another.
7. Use the Zoom Out command a few more times or scroll the mouse
8. From the Navigation bar, choose Zoom ➢ Zoom In, or roll the scroll
wheel on your mouse enough times to bring the view of the grid back
to the way it appeared when it was first displayed. You aren’t changing
the size of the grid, just the view of it. It’s like switching from a
normal to a telephoto lens on a camera The grid is more of a guide than an actual boundary of your drawing. For
most purposes, you can draw anywhere on the screen. The grid merely serves as
a tool for visualizing how your drawing will be laid out.
Because it serves as a layout tool for this project, you need to increase the area
covered by the grid from its present size to 60′ × 40′ (18 m × 12 m).